Webinars and Videos
The National Concrete Pavement Technology Center (CP Tech Center) aims to expedite the integration of advanced approaches, technologies, and research into everyday concrete paving practice via training webinars and videos, as well as other resources.
Upcoming Webinars
Register to join upcoming CP Tech Center webinar:
- December 14, 2021—Next Generation Concrete Pavement
Featured Webinar Video
Video Resources Library
The following multi-page table of past CP Tech Center webinars can be searched via the search bar by keyword, presenter, event, etc.—or navigated page-by-page from the bottom of the table.
| Video | Presenters | Event | Date | Resources | |||
|---|---|---|---|---|---|---|---|
| Understanding Penetrating Sealers for Concrete Pavements | 👤 John Kevern 👤 Kevin Fouch | Concrete Pavement Technology Tuesday | 2021 |
| 2021-11-09 | ||
| Machine vs. Concrete: Building Long-Lasting Concrete Pavement | 👤 Peter Taylor 👤 Larry Scofield | New and Evolving Technologies Webinar (Concrete Pavement Technology Tuesday) | 2021 |
| 2021-10-12 | 10/12/2021 1 Machine vs Concrete Building long lasting concrete pavements Peter Taylor, PhD, PE (IL), FACI Smooth Long lasting But how do we get there? • What levers can we pull? • What tests inform our decisions? PEM properties Uniform Workable 10/12/2021 2 Not segregated Smooth Finished Textured Cured Crack free 10/12/2021 3 In the Lab • Aggregate stability – AASHTO / ASTM protocols • Shrinkage – paste content • Transport properties (permeability) - resistivity • Cold weather resistance – air void system • Strength – compression / flexural In the Lab • Workability • Segregation No test • Response to vibration VKelly / Box • Edge slump VKelly / Box • Finishability Ruler • Other tests? In the Lab 11 Workability Transport Strength Cold weather Shrinkage Aggregate stability Aggregate System Type, gradation - - - - Paste quality Air, w/cm, SCM type and dose Paste quantity Vp/Vv - - - - Proportioning to achieve performance goals At the Batch Plant • Workability Power meter Call from the paving supervisor Data from the paver? • Uniformity No standard test • Stockpile control - • Water control Moisture probes • Loading sequence - • Mixing time - 10/12/2021 4 In front of the paver • Segregation No standard test (Tayabji) • Aggregate gradation • Uniform delivery • Placing method Behind the Paver • Finish and Smoothness Real time smoothness • Vibration Internal sensors • Pan setup • Grout box • Paver speed • Finishing Tining Bridge • Texture Sand Patch Noise • Tine setup • Bridge speed • Curing Zollinger method? • Curing Compound type • Spray rate • Timing Sawing • Crack free • Saw type • Blade • Depth • Timing UPV 10/12/2021 5 Where Next? • What have we missed above? • Small bites – started with PEM • Next bites • Vibration • Batch (water) control Vibration Purpose • To remove unwanted air • Assist with levelling The Theory • Reduce yield stress and viscosity • Allow bubbles to float out • Allow mixture to move The means • Vibration What Is Happening under Vibration? 19 Acceleration drops viscosity and allows air to float up and out Water moves horizontally Shaft oscillates in a circle sending out P and S waves Solids wobble And maybe rotate What is a good vibration? Ensures • No segregation • No entrapped air • Retain entrained air • No water movement But how? 20 10/12/2021 6 What is a good vibration? • Missing is fundamental understanding of the “how to” details • Energy • Frequency • Amplitude • Duration • Spacing • For a given • Workability • Air void system • Bleed / segregation • … 21 Hypothesis • Increased frequency • Moves water sideways • Excess vibration • Impacts air void system • Mixture segregation and bleeding increase effects For example: 22 Air loss and segregation • Unworkable concrete • Beaten into place 23 Water Movement 24 12,000 vpm8,000 and 10,000 vpm 10/12/2021 7 Rheology 101 Rheology 101 Rheology 101 Rheology 101 10/12/2021 8 Rheology 101 Preliminary Lab Work 30 Vibration analyzerAccelerometer • Vibration energy (RMS velocity, in/s) at a specific time period across the a range of frequencies – converted to acceleration • Vibrator reported voltage required to maintain fixed frequency Evaluating energy transfer 31 15” 6” 17” Sensors Vibrator 3” 3” 3” 3” 3” Vibrator Magnet Vibration Steel rod diameter: 0.5” Diameter of vibrator head: 0.9” 3” 2” Steel rods 13” 2” 4” 2” 2” 0.5” Rod Steel wire1.25” Matrix • Mixture 1 – low air (3.7%), high slump (10 cm), moderate w/c (0.4) • Mixture 2 – high air (7.2%), high slump (10 cm), moderate w/c (0.4) • Mixture 3 – low air (3.0%), low slump (2.5 cm), low w/c (0.25) • Mixture 4 – low air (3.1%), high slump (10 cm), low w/c with WR (0.29) • Frequency • Mixtures 1 - 4 at 8,000 vpm • Mixture 1 at 12,500 vpm 32 10/12/2021 9 Core samples 33 Drop Test • Drop 5 µL water on a dry surface • Record time for sheen to disappear • Longer is better • Great for localized comparisons 34 Effect of Air Content • Little difference in energy demand • Less thixotropy with air 35 Effect of Air Content 36 • Little difference in energy transfer 10/12/2021 10 Effect of Air Content 37 50.260.8 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V e rt ic a l ( m m ) Horizontal (mm) 29.0 39.6 50.2 60.8 71.4 82.0 92.6 103.2 113.8 Absorption time (s) 51.0 59.8 68.6 77.486.295.0 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V er tic a l ( m m ) Horizontal (mm) 42.2 51.0 59.8 68.6 77.4 86.2 95.0 103.8 112.6 Absorption time (s) (a) Mixture 1 - air 3.7% (b) Mixture 2 - air 7.2% • Water is shown to move away from vibrator tip Effect of Air Content 38 4.39 4.20 4.01 3.82 3.633.44 3.25 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V e rt ic a l ( m m ) Horizontal (mm) 3.07 3.25 3.44 3.63 3.82 4.01 4.20 4.39 4.58 Air (%) 7.62 7.35 7.09 6.82 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V e rt ic a l ( m m ) Horizontal (mm) 6.01 6.28 6.55 6.82 7.09 7.35 7.62 7.89 8.16 Air (%) (a) Mixture 1 - air 3.7% (b) Mixture 2 - air 7.2% • Air is shown to move up from vibrator tip Effect of Water Content • Higher energy demand in dry mixture 39 Effect of Water Content 40 • Less energy transfer in dryer mixture 10/12/2021 11 Effect of Water Content 41 • Water moves in both cases 50. 260.8 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V e rt ic a l ( m m ) Horizontal (mm) 29.0 39.6 50.2 60.8 71.4 82.0 92.6 103.2 113.8 Absorption time (s) 69.395.5121.8 148.0 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V e rti ca l ( m m ) Horizontal (mm) 43.0 69.3 95.5 121.8 148.0 174.3 200.5 226.8 253.0 Absorption time (s) (a) Mixture 1 - slump 10cm (b) Mixture 3 - slump 2.5cm Effect of Water Content 42 • Little difference in air movement 4.39 4.20 4.01 3.82 3.633.44 3.25 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V e rt ic a l ( m m ) Horizontal (mm) 3.07 3.25 3.44 3.63 3.82 4.01 4.20 4.39 4.58 Air (%) 4.123.92 3.71 3.51 3.31 3.11 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V e rt ic al ( m m ) Horizontal (mm) 2.70 2.90 3.11 3.31 3.51 3.71 3.92 4.12 4.32 Air (%) (a) Mixture 1 - slump 10cm (b) Mixture 3 - slump 2.5cm Effect of WRA • Little difference in energy demand 43 Effect of WRA 44 • More energy transfer in WRA mixture 10/12/2021 12 Effect of WRA 45 • Water moves in both cases 50.260.8 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V e rt ic a l ( m m ) Horizontal (mm) 29.0 39.6 50.2 60.8 71.4 82.0 92.6 103.2 113.8 Absorption time (s) 62.384.6106.9 129. 3 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V er tic al ( m m ) Horizontal (mm) 40.0 62.3 84.6 106.9 129.3 151.6 173.9 196.2 218.5 Absorption time (s) (a) Mixture 1 - without WR (b) Mixture 4 - with WR Effect of WRA 46 • Little difference in air movement 4.39 4.20 4.01 3.82 3.633.44 3.25 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V er tic a l ( m m ) Horizontal (mm) 3.07 3.25 3.44 3.63 3.82 4.01 4.20 4.39 4.58 Air (%) 3.27 3.03 2.792.55 2.32 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V e rt ic a l ( m m ) Horizontal (mm) 1.60 1.84 2.08 2.32 2.55 2.79 3.03 3.27 3.51 Air (%) (a) Mixture 1 - without WR (b) Mixture 4 - with WR Effect of Frequency • More energy demand at high frequency 47 Effect of Frequency 48 • More energy transfer in high frequency mixture • More loss over distance 10/12/2021 13 Effect of Frequency 49 • Water moves in both cases 50.260.8 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V e rt ic a l ( m m ) Horizontal (mm) 29.0 39.6 50.2 60.8 71.4 82.0 92.6 103.2 113.8 Absorption time (s) 72.1 79.0 85.9 92.8 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V er tic a l ( m m ) Horizontal (mm) 65.2 72.1 79.0 85.9 92.8 99.7 106.6 113.5 120.4 Absorption time (s) (a) 8,000 vpm (b) 12,500 vpm Effect of Frequency 50 • Appears that more air is lost to the high frequency system 4.39 4.20 4.01 3.82 3.633.44 3.25 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V er tic a l ( m m ) Horizontal (mm) 3.07 3.25 3.44 3.63 3.82 4.01 4.20 4.39 4.58 Air (%) 3.37 3.16 2.94 2.73 2.51 2.29 2.08 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 V er tic a l ( m m ) Horizontal (mm) 1.86 2.08 2.29 2.51 2.73 2.94 3.16 3.37 3.59 Air (%) (a) 8,000 vpm (b) 12,500 vpm Therefore • Hypothesis seems right • More research needed to pin down details • Potential to design “vibrator proof” or machine specific mixtures is real • As is real-time feedback to pavers and batch plants • Pooled fund is being launched 51 But wait, there’s more 52 10/12/2021 14 www.cptechcenter.org 10/12/2021 1 ACPA Research, Technology, and Innovation Functional Committee (RT&I) Larry Scofield Purpose: • To Develop and Guide the Association’s Research Needs and Priorities • To Communicate These Needs/Priorities to the Research and Industry Communities • Be a Lightning Rod for New Ideas RT&I Members Chairman: Matt Fonte- Castle Rock Vice Chairman: Jim Mack- Cemex Staff: Dr. Mark Snyder- Consultant Larry Scofield-IGGA/ACPA Concrete Batching Paul Jaworski Minnich In-Service in Hrs Gordon Smith CP Tech Center Paver Changes Dave Scuillo Golden Triangle Real Time Sensing Dr. Tyler Ley OSU 2040 Vision Gary Fick Transtec Task Forces Members 10/12/2021 2 Process: • Brainstormed What the Industry Needed to Have • RT&I Group Then Prioritized Needs Statements • Created Five Task Forces to Develop the Highest Ranked Areas • Submit Ideas/Needs to ACPA Market Forum • Developing Problem Statements for Research Needs 2040 Task Force • Reduced Carbon Footprint • Heavy Loads and Platooned Trucks • Construction and Maintenance Techniques that Have Low Impact on Traffic • Long Life Pavement • Build Things that Last- Cheaper- Optimizing Batching TF • Material Moisture Sensing and Automated Compensation • Use of Dual Cement Weigh Scales for Improved Cementitious Material Blending and Distribution • Development of Internal Batch Drum Sensors and Tools for Monitoring and Controlling/adjusting Critical Factors that Impact Batch-to-Batch Uniformity Put In-Service in Hrs TF • Performance Parameters Have Been Identified for Each Application (new construction/overlays vs. repairs) • RCC • Lessons Learned in Fast Track 10/12/2021 3 Real Time Sensing TF • Focused on Paving Process Impacting Smoothness • Determined Factors Required to Routinely and Consistently Make Smooth Concrete Pavements • Attempting to Construct Some Test Sections For Evaluation Paver Changes TF • Drop-off (safety) issues in paving. • Tie bars – usually needed to prevent joint opening, but a problem in staged construction. • Early opening mixes needed possibly with different opening times for cars vs heavy trucks Summary • Task Forces are a Living Process • Conducting Webinars to Show Case Emerging Technologies • Going Out for a Synthesis Project to Summarize and Assess Technologies to Determine their Potential to Control Aggregate Moisture Levels During Batching • Attempting to Construct Test Sections to Evaluate Machine Parameter Impacts on Initial Smoothness • Potential For Agencies to Use Pooled Funds to Push Technology Forward Questions Tesla Edison | |
| Advancements in Performance-Engineered Mixtures (PEM) | 👤 Peter Taylor 👤 Mike Praul | Concrete Pavement Technology Tuesday | 2021 |
| 2021-09-14 | 9/20/2021 1 PEM is not over… Peter Taylor and Mike Praul A Better Specification • Require the things that matter • Measure them at the right time • Prequalification • Process control • Acceptance 2 What do we need? • Transport properties (permeability) • Aggregate stability • Cold weather resistance • Strength • Shrinkage • Workability 3 Transport properties (permeability) • All deterioration mechanisms involve fluid movement • Keep water out = longer life • Test using resistivity 4 9/20/2021 2 Aggregate Stability • Alkali aggregate reaction • AASHTO R80 / ASTM C 1778 5 Cold Weather • Freeze-thaw • Saturation • Entrained air (SAM) • De-icing salts • Sufficient SCM 6 Strength • Strong enough to carry loads • Cylinders • Beams • Maturity • Normally we get more than we need • Not a substitute for the other properties 7 Workability • Not too wet • Not too dry • Test with VKelly or Box 8 9/20/2021 3 How do we proportion to achieve design goals? 9 Workability Transport Strength Cold weather Shrinkage Aggregate stability Aggregate System Type, gradation ‐ ‐ ‐ ‐ Paste quality Air, w/cm, SCM type and dose Paste quantity Vp/Vv ‐ ‐ ‐ ‐ Implementation… 10 Implementation 11 Not a problem in our state Haven't thought about it A good spec already in place Some interest Considering change Adopted change Transport 1 3 3 8 3 1 Freeze thaw 2 2 10 5 Oxychloride 15 3 1 Aggregates 2 1 16 Strength 19 Shrinkage 11 3 1 3 1 Workability 4 6 6 1 2 Steps to Long Life Design Levers Gradation Paste Volume Cementitious Admixtures Batching Uniformity – Water – Cementitious system – Aggregates Mixing – Time – Energy Transportation Mixing Workability – Time and weather – Added water / admixtures Uniformity Placement Handling / Vibration ‐ Bleeding ‐ Segregation ‐ Air void system ‐Water movement Target performance Workability Durability Strength Finishing Surface finish Curing Sawing Measure! Measure Measure! 9/20/2021 4 Still working on.. • Tools in the lab: • Response to vibration • Tools in the field: • Workability, air void stability, bleed, segregation • Feedback to the batch plant • Water content • Curing • Time to saw 13 9/20/2021 1 Image Here Office of Infrastructure M ICHAE L F . P RAUL , P E SE NIOR CON CRE TE E N GIN E ER F HWA, OF F ICE OF IN F RASTRU CTURE PEM: Where We Are Today All images FHWA unless otherwise noted National Concrete Pavement Technology Center Webinar September 14, 2021 PEM and Performance Specification Background QC Tool PEM Project Highlights and States’ Status Sustainability Live From the MCTC Topics Evolution of Concrete Acceptance Testing ASTM C231ASTM C143 Slump Cone Pressure Meter 1981 Rapid Chloride Penetrability Test 1922 1949 ASTM C1202 1920 198019601940 2000 Image Pixabay New Technologies 9/20/2021 2 Performance Related Specifications (PRS) Performance is NOT… Performance Based Specifications (PBS) Get beyond slump, strength, and total air content as determinants of concrete quality Incorporate tests that correlate to service life durability Appropriately apply those tests in agency acceptance and contractor quality control programs Develop specifications and practices to leverage quality control Remove prescriptive restraints from specifications Minimum cement content Single aggregate gradation Slump Performance Engineered Mixture (PEM) Concepts Better Assessment of Quality? Option 1Option 1 QC info: None Strength Slump Total Air Option 2Option 2 QC info: Unit weight Calorimetry Strength Resistivity SAM number Jerry Voigt, ACPA Past President (ret.) “It’s the agency’s responsibility to allow for innovation. It’s the contractor’s responsibility to deliver.” Image ACPA 9/20/2021 3 How Do Contractors Deliver in a Performance Specification? Image Pixabay Prescriptive vs. Performance Specifications Prescriptive/MethodPrescriptive/Method Agency dictates how the material or product is formulated and constructed Based on past experience Minimal/uncertain ability to innovate Requires agency to have proper manpower and skill set to provide oversight PerformancePerformance Agency identifies desired characteristics of the material or product Contractor controls how to provide those characteristics Maximum ability to innovate Reduced oversight burden on the agency Quality Control for Concrete Paving: A Tool for Agency and Industry Developed under a cooperative agreement; use is not required by Federal statute or regulation. Technical Advisory Committee (TAC) Roster State Agencies Contractors Industry Associations Maine DOT – Rick Bradbury Rieth-Riley – Pete Capon ACPA – Leif Wathne, Gary Mitchell Michigan DOT – John Staton Cedar Valley – Craig Hughes NRMCA/RMCREF – Colin Lobo Ohio DOT – Dan Miller AJAX – Hugh Luedtke PCA – Paul Tennis Iowa DOT – Todd Hanson Duit Construction – John Privat WCPA – Kevin McMullen Minnesota DOT – Maria Masten FHWA Illinois Tollway – Cindy Williams Mike Praul, Sam Tyson, Dennis Dvorak, Jeff Withee, Bob Conway 9/20/2021 4 QC Tool Overview Roles and responsibilities for agencies and industry under performance specifications Organizational and project-level QC PEM approach Mix design and production QC QC monitoring by both agency and industry Statistical tools, control charts, etc. QC Tool References Review of Agency QC Requirements Commonly and less-commonly specified QC requirements (from review of roughly 15 agencies) Example QC Plan Provisions QC Plan Outline Appendix D: Suggested Model QC Plan Based on NorthEast Transportation Training and Certification Program (NETTCP) Model QC Plan Developed under a cooperative agreement; use is not required by Federal statute or regulation. Material is included for informational purposes only and are not intended to reflect a preference, approval, or endorsement of any one product or entity by the Federal government. PEM Implementation Incentive 19 States + FHWA & Industry (June 2021) PEM Implementation Incentive Pilot Project PEM approach typically is beneficial to State and industry PEM mix tested better in all tests vs. Class C 2nd supplier was reluctant to participate Determined QC requirements were not much more than they currently do Mix looked and placed better than Class C Needs Training in new tests Understanding roles and responsibilities in a performance specification (including QC monitoring) Consider 56-day testing for resistivity Developing next project in NYC area (structural) New York Highlights 9/20/2021 5 New York Highlights Box Test: 45#/cy reduction in cement Contractor now using to develop mixes Super Air Meter notes Need for technician training Attention to detail for correlation testing Concern with gauge durability Surface Resistivity Invaluable information for agency and industry Easy to perform, no changes needed Expanded typical QC requirements 2020 project use proposed by contractor. Approved! Iowa Highlights Iowa Highlights “After dropping 45 pounds per cubic yard of cement out of our QMC mix and performing the Box Test, we were astonished and actually paved a considerable quantity with the PEM adjusted mix with very good results.” (contractor) 19 Box Test Highly useful in mix development and evaluation. (contractor) Simple, easy test. Potential to add to specification. (NCDOT) Super Air Meter After some training, readily incorporated into QC. (contractor) Doing more shadow testing and consider future use. (NCDOT) Surface Resistivity Easy. Readily incorporated into QC. (contractor) Easy. Affordable equipment. Will equip all State labs. (NCDOT) UNC-Charlotte working to develop 28-day result to correlate with 56-day results. North Carolina Highlights 9/20/2021 6 North Carolina QC Image: Dr. Tara Cavalline, UNCC Image: Fred White, Lane Construction “Valuable experience” (contractor and NCDOT) “Due to project schedule, we were unable to apply the PEM criteria during the preliminary mix design phase. However, going forward, we intend to implement PEM guidelines on future PCCP projects.” (contractor) “The Department will continue to explore PEM to see how these tests and other AASHTO PP 84 provisions will work with our daily operations.” (NCDOT) NCDOT will pilot PEM bridge project. North Carolina Highlights Colorado Open House (2018) Spec revision (2019) Removed max and min cement content Allows optimized aggregate gradation Box Test in mix design Resistivity Max shrinkage Industry support for PEM 23 Pennsylvania 2 PEM projects (2018 & 2019) April 2020 spec lowered w/c ratio to 0.42 Testing: Shrinkage (bridge decks) Resistivity 4 SAMs DOT plans to continue to evaluate the Box Test, resistivity, SAM Industry support for PEM 24 9/20/2021 7 Kansas Open house & shadow testing 2019 Training Day – all DOT districts trained with SAM (2019) Considering requiring SAM in mix design for 2022 Resistivity testing for 5 years Optimized aggregates for 10 years 25 Minnesota Have optimized aggregate gradation 0.40 max w/c ratio with incentives Interested in SAM training Purchased Phoenix water content equipment Open house in 2019, shadow project in 2020 26 Michigan Considering SAM in mix design phase DOT purchased 19 SAMs Considering incentive for lower w/c ratios Optimized aggregates for > 20 years 27 Wisconsin SAM shadow testing in mix design phase (since 2017) Considering SAM for acceptance testing (2021) Incentive for aggregate gradation & cement reduction from 564 pcy to 520 pcy 28 9/20/2021 8 PEM and Sustainability 28-day mix design strengths are being met in 7 days 28-day mix design strengths are exceeded by more than 60% 56 to 90-day strengths exceed the 28-day mix design strength by more than 80% High cement content is nearly always the primary cause Negative impacts of high cement content Increased cracking potential Higher permeability Higher cost Less workable concrete Increased production of carbon dioxide Observations From MCTC Data Move to performance-type specification language; eliminate mandatory cement content requirements Optimize aggregate gradation Use supplementary cementitious materials Use maturity testing to determine opening times Promote quality control in the plant to provide more consistent production Ways to Reduce Cement Content Super Air Meter (SAM) Surface/Bulk Resistivity Maturity Box Test/V-Kelly Semi-adiabatic calorimeter “Live From the MCTC” Training/Workshops Phoenix (fresh water content) MIT SCAN-T3 MIT Dowel Scan HIPERPAV Optimized Gradation software 9/20/2021 9 https://www.fhwa.dot.gov/MCTC MCTC Website Questions? Contact info: Michael.Praul@dot.gov 207-512-4917 Image Pixabay The contents of this presentation do not have the force and effect of law and are not meant to bind States in any way. This presentation is intended only to provide clarity regarding existing requirements under the law or agency policies. PEM Webinar – Questions and Answers The questions submitted during the webinar follow with answers that our speakers have provided. Key resources available include: https://cptechcenter.org/performance-engineered-mixtures-pem/ https://store.transportation.org/Item/PublicationDetail?ID=4599 https://www.fhwa.dot.gov/MCTC 1. Are most agencies using the Surface Resistivity (AASHTO 358) test more often than the Bulk Resistivity (AASHTO 119) test? Are they mostly using it for construction QC and acceptance as opposed to qualification of mix designs? District of Columbia There are a number of states that have incorporated resistivity testing into their program; all are using Surface Resistivity. FL, LA, ME, KS, CO, and UT use SR, either for mix approval or as part of project acceptance. NC is developing a SR specification with plans to implement for acceptance in the near future. MI is currently evaluating Bulk Resistivity. 2. It would be great to have all these PEM related activities (SAM, MITScan T3, Resistivity, Mobile lab, etc..) organized in one document in a logical sequence. Florida Have a look at AASHTO PP84 and the CPTech website referenced about 3. Any discussion within ACI 318 for an optional performance spec in lieu of the prescriptive durability classifications? Idaho Interesting thought. We have not had any contact with that committee. We will follow up with them. 4. Can we (City of Ames) coordinate with ISU to see concrete tests (specially freeze and Thaw)? Iowa Sure – call me (Peter) 5. Need more information on Box Test 45#/cy reduction in cement. Iowa See the report at https://intrans.iastate.edu/app/uploads/sites/7/2019/06/Iowa-PEM- Report_2019-06-20_Final.pdf 6. Have you had any issues getting test data from aggregate source that not used on a regular basis? Since some on the PEM tests take time, and there may not be a lot of time from bid to construction. Oregon We have not seen this be an issue on the pilot projects to date. 7. Are you working with ACI on these cement optimization methods? Pennsylvania https://cptechcenter.org/performance-engineered-mixtures-pem/ https://store.transportation.org/Item/PublicationDetail?ID=4599 https://www.fhwa.dot.gov/MCTC Yes – we are aiming to get them into the ACI training program. Some states are planning to add the tests to their in-state training programs. 8. What type of testing frequency is recommended for the SAM during production (since it takes a bit longer to perform than a standard air meter)? Have folks needed additional inspectors to keep up with production? Virginia We are not recommending any changes in testing frequency based solely on changing from the Type B pressure meter to a SAM. While it is correct that the SAM takes longer to run, once technicians gain some experience with it, the time increase is marginal. Some agencies are evaluating using the SAM as part of the mix design approval process but staying with the Type B meter for field acceptance. 9. Are there any states where there is not industry support for PEM? Washington Not that I am aware of 10. Could the FHWA mandate use of PEM and tie federal funding to help make it stick? Washington FHWA does not have the regulatory authority to issue such a mandate. FHWA is devoting significant resources to the PEM effort, including: • Continuing financial support to the pooled fund. • Developing implementation tools through our Concrete Cooperative Agreement with the National Concrete Pavement Technology Center (e.g. the QC tool covered in the presentation). • Providing implementation technical assistance and training to agencies and industry via the Mobile Concrete Technology Center program. PEM Webinar – Questions and Answers | |
| Proper Resiliency Planning Prevents Disaster and Aids in Crisis Management—A Concrete Perspective | 👤 Greg Dean | Concrete Pavement Technology Tuesday | 2021 |
| 2021-08-10 | 8/13/2021 1 Resiliency: Proper Planning Prevents Disaster and Aids in Crisis Management A Concrete Pavement Industry Perspective Greg Dean Executive Director Carolinas Concrete Paving Association gdean@pavementse.com CP Tech Center Webinar August 10 2021 aka Boosting Pavement Resilience in a Changing Climate The Need for Resilient Pavements Well‐documented in prior webinars, peer exchanges, ETC https://youtu.be/LdQ8ELIk3IM (Jim Mack, Cemex, FC&PA PaveWise concrete conference) https://sites.google.com/view/resiliency‐peer‐exchange‐1/home FHWA Peer Exchange #1‐Oct 2020 https://sites.google.com/view/resiliency‐peer‐exchange‐2/home FHWA Peer Exchange #2‐Dec 2020 Improving a Pavement’s Resiliency https://cptechcenter.org/events/spring‐2021‐national‐concrete‐consortium/ (Leif Wathne, ACPA) Current knowledge, research gaps and design trends for various transportation modes Resilience will be tested Freight (loads) will continue to rise significantly Carolinas impacted by TWO 500‐year flood events Hurricane Matthew (2016) & Hurricane Florence (2018) I‐95 Lumberton, NC (2016) I‐95 Lumberton, NC (2016) I‐40 Pender County 4‐Days post hurricane (2018) With Hurricane Florence, NC had over 2500 road closures 8/13/2021 2 2020 A Very Busy, Record‐ Breaking Year • Most Active (30) and • 7th costliest, nearly $47B in estimated damages • 5th Consecutive year above average activity • 12 Storms made landfall in the US Nebraska DOT reported 1,500 road miles closed FLOODING IN THE PLAIN STATES WAS SEVERE MARCH 2019 Flooding is NOT only a Coastal Issue Iowa I-29 Impacts - 7 - FLOODING IS THE PRIMARY CLIMATE RISK TO INFRASTRUCTURE Risk can occur as both sudden shocks & long-term recurring chronic pressures Airports Rail Roads River Seaports Wildfires Sea-level rise & tidal floods Riverine & pluvial flooding Hurricanes, typhoons & storms Tornadoes & wind events Drought Heat (air & water) Little or No Risk Increased Risk Source: McKinsey & Company, Will infrastructure bend or break under climate stress?, McKinsey & Company, August 19, 2020 https://www.mckinsey.com/Videos/video?vid=6180836320001&plyrid=HkOJqCPWdb&aid=A21DD0A9-7DA8-44A2-87E0-B4944177F295 Climate risk increases operating costs & exacerbates the infrastructure funding gap Transportation Asset FUTURE CLIMATE CONDITIONS WILL NOT RESEMBLE THE PAST USGCRP, 2018: Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II: Report‐in‐Brief [Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, 186 pp. Global mean sea level: 7–8 inches higher since 1900 - about half since 1993 Expected to rise by 1–4 feet by 2100 Increased Extreme heat events and drought: Increased incidence of large forest fires U.S. severe storms, heavy precipitation events: Greater intensity and frequency Continued increases expected 8/13/2021 3 SEA LEVEL RISE IS ALREADY IMPACTING COASTAL ZONES Sunny sky flooding is becoming a too common occurrence SR54 East of Fenwick, DE South Bowers Beach , DE DE Photos courtesy of Jim Pappas, DELDOT; FL Photos courtesy of Amy Wedel, FC&PA Charleston, SC Miami, FL High Tide (Charleston SC) Flood Days Low to Intermediate (Middle) Charleston, SC Sea Level Rise Year Low (~1 foot) Middle (~3 feet) 2022 7 Days 16 Days 2042 22 Days 73 Days 2052 34 Days 130 Days Source: U.S. High Tide Flooding Probability Scenarios through 2100 (esri.com) BOOTS required! Defining Resiliency • Identify risks posed by climate change and extreme weather events • Integrate consideration of these risks into its planning, operations, policies and program areas The ability to anticipate, prepare for, and adapt to changing conditions and withstand, respond to, and recover rapidly from disruptions. Source: FHWA Order 5520 - 12 - INTRODUCTION TO RESILIENCE The ability to … anticipate, prepare for, and adapt … withstand, respond to, and recover rapidly…1 Performance Time 1) Drop in Performance 2) Recovery time (full, or partial improvement) Resilience with respect to an event (e.g. Flooding, fire, earthquake, etc ) is characterized by two parameters: 1. Drop in performance, induced by the event (e.g. reduced ability to carry load). 2. Recovery time to reinstate or improve performance. Green is more resilient than Red • Faster recovery time • Higher level of service Blue is a hardened 2 system as it has a higher final performance level 1. FHWA Order 5520: Transportation System Preparedness and Resilience to Climate Change and Extreme Weather Events 2. Hardening Infrastructure – Elevating, upgrading, relocating assets, flood walls, berms and levees, etc. 8/13/2021 4 - 13 - INCREASED FLOODING IS IMPACTING OUR PAVEMENT STRUCTURES Need to distinguish between Inundation and Washout Impacts Washout Mobility Disruptor Rapid flow of flood water / high current that scours and washes out the pavement structure Pavement type has little impact Inundation Silent Killer The rise of water that submerges the pavement. No rapid flow or current Pavement type does have an impact - 14 - Rigid and Flexible Pavement Transmit Loads Differently Concrete’s rigidity spreads the load over a large area & keeps pressures on the subgrade low • Load ‐more concentrated & transferred to the underlying layers • Higher deflection • Subgrade & base strength are important • Requires more layers / greater thickness to protect the subgrade Flexible Pavement Structure Rigid Pavement Structure 7000 lbs load pressure 15 - 20 psi Flexible Base Subbase Subgrade pressure ~ 3 - 7 psi Rigid Subbase Subgrade • Load – Carried by concrete and distributed over a large area • Minor deflection • Low subgrade contact pressure • Subgrade uniformity is more important than strength • Lowered subgrade strength & reduced modulus • Reduced load carrying capacity and >1 year recovery time • Loading accelerates pavement damage / deterioration • Consumes fatigue life faster Reduced pavement life • Maintains high level of strength / stiffness • Subgrade is weak, but still uniform • Spreading of the load means subgrade is not overstressed • Little impact on the serviceability / life Flooding does not impact concrete’s load carrying capacity to the same degree as asphalt’s 7000 lbs load - 15 - RESEARCH FINDINGS INDICATE IT TAKES UP TO 1 YEAR FOR THE SUBGRADE STRENGTH TO RECOVER FROM FLOODING After the flood waters recede, the pavements are structurally vulnerable For this case, this strength loss is a 40 to 60% reduction load carrying capacity and about 3 years of life Sources: 1. Decision Support Criteria for Flood Inundated Roadways: A Case Study, A. Gundla, Ph.D., E. Offei, Ph.D. G. Wang, Ph.D., P.E. C.Holzschuher, P.E. and B. Choubane, Ph.D., P.E., Presented at the 2020 TRB Annual Mtg 2. Western Iowa Missouri River Flooding— Geo-Infrastructure Damage Assessment, Repair, and Mitigation Strategies; Center for Earthworks Engineering Research, Iowa State University, Report No. IHRB Project TR-638 US 441 in Alachua County, Florida between MP 7.960 to MP 9.680 - 16 - WHEN LOOKING AT PAVEMENT’S RESILIENCY, NEED TO RECOGNIZE DAMAGE FROM 2 DIFFERENT SOURCES / TIMES Impact Types / Timing • Primary / Direct Impacts – alters the pavement structural or functional capabilities • Secondary / Indirect Impacts – Impacts due to recovery activities or use • Rescue and Emergency response during the disaster • Recovery activities (clean up and rebuilding) after the disaster 1 2 To have a resilient pavement system requires that both aspects be addressed 8/13/2021 5 - 17 - RELIEF AND RESCUE EFFORTS WILL TAKE PLACE Loading occurs both during the crisis and long after Joplin, MO Tornado (2011) Debris Hauling from Camp Fire, Paradise, CA (2018) 3.66 million tons removed over a nine-month period Hurricane Florence (2018) - 18 - DEBRIS REMOVAL CAN TAKE PLACE FOR MONTHS Further exacerbating the pavement damage while weakened Source: Amy Wedel, FC&PA - 19 - FHWA Pavement Resiliency Peer Exchange (#1) Poll Results from (39) Attendees ACPA, NAPA, DOT’s (10), Universities (5), Consultants Source: FHWA Pavement Resiliency Peer Exchange 1. Inundation due to flooding 2. Erosion/washouts/scour 3. Sea-level rise related issues 4. Temperature impacts on pavement materials and pavement design process. 5. Repeated occurrence of extreme events at the same location. Source: FHWA Pavement Resiliency Peer Exchange 1. Pavement designs that take flooding concerns into account 2. Making existing pavements more resilient (primarily due to inundation) 3. Pavement-ME calibration for forward- looking climate-related inputs 4. Planning for and rapidly responding to extreme events to maintain and restore operations 5. Uncertainty about structural integrity of base layers. TOP ISSUES of Concern - Q1 Poll following 1st Break-out Most Pressing PAVEMENT Issues - Q2 Poll following 2nd Break-out Boosting Pavement Resilience in a Changing Climate The Need for Resilient Pavements Well‐documented in prior webinars, peer exchanges, ETC https://youtu.be/LdQ8ELIk3IM (Jim Mack, Cemex, FC&PA PaveWise concrete conference) https://sites.google.com/view/resiliency‐peer‐exchange‐1/home FHWA Peer Exchange #1‐Oct 2020 https://sites.google.com/view/resiliency‐peer‐exchange‐2/home FHWA Peer Exchange #2‐Dec 2020 Improving a Pavement’s Resiliency https://cptechcenter.org/events/spring‐2021‐national‐concrete‐consortium/ (Leif Wathne, ACPA) Current knowledge, research gaps and design trends in various transportation modes Low‐hanging fruit that can make a pavement more resilient? (FHWA Peer Exchange priorities) 8/13/2021 6 Low Hanging Fruit for Improved Pavement Resilience GOOD resources can be found… Articles & Polling •How Severe Weather Damages our Roadways (August 2019) •Extreme Weather and Climate Adaptation (June 2019) •Federally Funded Infrastructure Must Be Flood Ready •Public Roads - Boosting Pavement Resilience (Autumn 2018) •Texas Roadways Proven Resilient After Hurricane Flooding •PEW Charitable Trusts Flood Infrastructure Survey (Feb 2020) Reports and Publications •LTPP Tech Brief - Impact of Environmental Factors on Pavement Performance (Dec 2016) •FHWA - Climate Change Adaptation For Pavements (August 2015) - 22 - Pavement Resiliency FHWA – Climate Change Adaptation for Pavements H O T T E R Climate Change Impact Affected Components & Strategies Higher Extreme Maximum Temperature Flexible Pavement • Increased potential for asphalt rutting and shoving during extreme heat waves Higher Extreme Maximum Temperature Rigid Pavement • Increased risk of concrete pavement “blow ups” due to excessive slab expansion 1. Use Shorter Joint spacing in new designs 2. Keep joints clean and in extreme cases, install expansion joints in existing pavements Table 1a. Pavement Design - Temperature Items (adapted from Meyer et al. 2014) - 23 - Pavement Resiliency FHWA – Climate Change Adaptation for Pavements W E T T E R Climate Change Impact Affected Components & Strategies More Extreme Rainfall Events • Increased need for surface friction meaning potentially more focus on surface texture and maintaining skid resistance 1. Maintain positive cross slope to facilitate flow of water from surface 2. Increase resistance to rutting 3. Reduce splash/spray • Increased need for functioning subdrainage o Adequacy of Design, installation and maintenance of subdrainage • Reduction of structural capacity of unbound bases and subgrade when pavements are submerged o Develop a better understanding of how submergence affects pavement layer structural capacity and strategies to address it Table 1b. Pavement Design - Precipitation Items (adapted from Meyer et al. 2014) - 24 - Pavement Resiliency FHWA – Climate Change Adaptation for Pavements W E T T E R Nov 2020 / I-95 rainfall damage Climate Change Impact Affected Components & Strategies Higher Average Annual Precipitation • Reduction in pavement structural capacity due to increased levels of saturation 1. Reduce moisture susceptibility of unbound base/subgrade materials through stabilization 2. Ensure resistance to moisture susceptibility of asphalt mixes • Improved surface and subsurface pavement drainage • Will likely negatively impact construction scheduling Table 1b. Pavement Design - Precipitation Items (adapted from Meyer et al. 2014) 8/13/2021 7 - 25 - Concrete overlay increases both the height and the structural strength of the roadway 7000 lbs load. 7000 lbs load. pressure 15 - 20 psi Asphalt Base Subbase Subgrade Pressure ~3 - 7 psi at the top of the Asphalt layer Base & subgrade pressures are even lower Concrete Asphalt Base Subbase Subgrade Road Elevation raised the height of the overlay ACTIVITIES THAT CAN BE USED TO “HARDEN THE PAVEMENT SYSTEM” Use Concrete Overlays - 26 - Concrete Overlay Adoption Growing… 0% 2% 4% 6% 8% 10% 12% 14% Prior to 2000 2000-2004 2005-2009 2010-2014 2015-2019 2.0% 2.0% 4.3% 11.3% 12.4% O ve rla ys a s Pe rc en ta ge o f To ta l C on cr et e Pa vi ng , S Y RCC Overlay Greenville, SC US 69 Oklahoma Concrete overlays included in FHWA’s EDC6 BCOA Example Unbonded Example - 27 - OVERLAYS can IMPROVE the PAVEMENT’S RESILIENCE Innovations in Overlays Create a Top-Notch Pavement Network with TOPS | Innovator | 2021 | July / August (dot.gov) Overlays reduce maintenance, maximize previous investments, and reduce user delays (fewer work zones) due to extended service life of pavement structures. In addition, some TOPS products increase skid resistance, improve resiliency in flood-prone areas, reduce splash and spray, and reduce noise. US Department of Transportation Federal Highway Administration - 28 - Examples of Inundation of Airfield Pavements Coastal NC Airport exposed to Hurricanes MS Airport exposed to Riverine Floods 8/13/2021 8 Federal Aviation Administration Design Circulars Comparison of 2016 & 2021 AC 150/5320‐6F (Nov 2016) • The term “water inundation” is NOT mentioned within the prior circular • The term “water table” mentioned Four times within the prior circular NEW AC 150/5320‐6G (June 2021) • The term “water inundation” used TWO times within new circular • The term “water table” used Five times within new circular • Added discussion regarding subgrade stabilization (Chapter 2) • Expanded discussion of stabilized base course and drainage layers • P‐207 Full Depth Reclamation (FDR) shown as a viable stabilized base course when certain conditions are met - 30 - Moisture infiltrates base • Through high water table • Capillary action • Causing softening, lower strength, and reduced modulus FDR reduces permeability • Helps keep moisture out • Maintains high level of strength and stiffness even when saturated High water table Un-stabilized Granular Base FDR w/ Cement- Stabilized Base 100 psi 15 psi 100 psi 4 psi FDR as a Resilience Hardening Solution Increases rigidity, reduces permeability, & reduces moisture susceptibility The stabilized base can be topped with either asphalt or CONCRETE surface - 31 - Elizabeth City Airport FDR & P-501 (Concrete) combine for a RESILIENT Pavement Solution Federal Aviation Administration Advisory Circular 150/5320‐6G (June 2021) 2.3.9.11.1 Laboratory CBR (California Bearing Ratio) Perform laboratory CBR tests in accordance with ASTM D1883, Standard Test Method ETC. Conduct laboratory CBR tests on materials obtained from site and remolded to the moisture and density that will be required during construction. Samples should be soaked prior to testing. Pavement foundations tend to reach nearly complete saturation after about 3 years. The use of a soaked CBR test simulates the condition of a pavement that has been in service. A soaked CBR also represents the time of year when the weakest subgrade is present, i.e. periods of high moisture such as spring thaw or following seasonal storm events. 8/13/2021 9 AC 150/5320‐6G (June 2021) 2.4 Subgrade Stabilization 2.4.1 Where the mean subgrade strength is lower than CBR 5 (elastic modulus approx. 7,500psi) it is recommended to improve the subgrade chemically, mechanically, or by replacement with suitable subgrade material. 2.4.2 When the mean subgrade strength is less than a CBR 3 (elastic modulus approx. 4,500 psi) improve the subgrade through stabilization or replacement with suitable subgrade material. Federal Aviation Administration Advisory Circular 150/5320‐6G (June 2021) 2.4 Subgrade Stabilization 2.4.3 In addition, consider subgrade stabilization if any of the following conditions exist: poor drainage, adverse surface drainage, frost, periodic water inundation or the need to establish a stable working platform. Use chemical agents, mechanical or geosynthetic methods to stabilize subgrades. 2.4.4 Stabilize subgrade materials to a minimum depth of 12 in (300 mm), or to the depth recommended by the geotechnical engineer. Pope Army Airfield 6‐inch cement stabilized drainage layer (COE Spec) Stabilized Drainage Layer Improved Resiliency 8/13/2021 10 - 37 - Charleston Executive (JZI) Airport Johns Island, SC 11-inch Unbonded Overlay (2010 Construction) 2016 PCI Data from Pavement Management Report 2010 LCD-RW Concrete Overlay range from 93 to 96 (weighted average 94, 1 point per year drop) 2010 LCD-TW Connectors (Tie-Ins) Asphalt range from 77 to 86 (weighted average 82, 3 points per year drop) 2008 LCD – Taxiway A Asphalt = 75 (drop of 3.1 points per year) Stono River Owner’s Quotes (During Open House Event) A Concrete Overlay kept us “out of the subgrade” vs. reconstruction option. A Concrete Overlay raised our pavement elevation out of the high water table (e.g. boosting resilience) Our original concrete surface lasted 60+ years, no reason why this (new concrete) surface cannot last another 60 years! - 38 - High Water / Flood Inundation Matters Charleston Exec (JZI) Airport 0 0.5 1 1.5 2 2.5 3 Asphalt Concrete Deterioration PCI Points/year PCI High PCI Low Summary Airfield concrete pavements deteriorate at rate of 0.5 to 1.2 PCI points per year JZI Concrete (RW) deteriorating at 1 point per year Asphalt pavements deteriorate at rate of 1.5 to 2.5 PCI points per year (avg = 2) JZI Asphalt (TW) deteriorating at 3 points per year (50% faster than typical) 3X faster deterioration Asphalt vs PCCP Source: Performance Trends in Airport Runway Pavements (2014 FAA Worldwide Airport Tech Transfer Conference) and SC 2016 Airfield Pavement Management Report (JZI PCI data) 50% faster - 39 - Resiliency of Concrete Recognized Rehabilitation of Runways at JFK Port Authority of NY & NJ Press Release (April 2019) “Use of Concrete will extend runway’s useful life to 40 years, rather than 8-12 years with asphalt.” “The rehabilitation will provide aircraft a solid concrete runway that is more RESILIENT than asphalt and will increase the useful life of runway by four times” - 40 - East Coast Greenway Design Guide • Longest-lasting (25+ year) & lowest maintenance surface • Suitable for Areas prone to flooding Concrete trails typically have the longest lifespan of any trail surface... 8/13/2021 11 Sunny Day Flooding can lead to Early Pavement Deterioration Spread the Load by using Concrete Pavement Photos courtesy of Erdman Anthony https://www.erdmananthony.com/Our‐Projects/project/484 Yacht Harbor Manor Neighborhood Improvements, Riviera Beach, Florida B E F O R E A F T E R In Summary…Concrete Pavement Industry offers: several HARDENING TECHNIQUES Conventional Concrete Pavement Concrete Overlays Roller Compacted Concrete (RCC) Full Depth Reclamation (FDR) w/ Cement Thin Concrete Pavement Pervious Concrete - 43 - • There is greater recognition toward making our pavements more “Resilient” ‒ Need to define specific actions that agencies should consider when dealing with pavements ‒ Need to define how each specific “climate risk” will impact the system ‒ Must account for secondary impacts • In areas where pavements have a history of flooding (or in flood prone areas) ‒ Require pavement designs be based on lowered subgrade strength ‒ Use Stiffer or stiffen the existing pavement ‒ Viable low-cost solutions, such as concrete overlays and cement stabilization strategies can be used as mitigation / hardening strategies 1 2 Pavements are being negatively impacted by our changing climate. Green and Grey solutions will be required to improve our nation’s infrastructure resilience. Greg Dean 919‐656‐5930 gdean@pavementse.com Wishing to learn more on pavement resiliency? 12th International Conference on Concrete Pavements Sep 27 – Oct 1 Register 8/13/2021 12 Greg Dean, Executive Director ‐ Carolinas Concrete Paving Association Greg’s responsibilities include the education and marketing of concrete pavements for Airport, Highway and Local Road applications within North and South Carolina. He currently serves on the ACPA’s Engineering and Design Committee and a member of the resiliency group as part of ACPA’s Sustainability initiative. During his time (2008‐2013) as Airport Director of the ACPA‐SE Chapter he began observing how deterioration rates of airfield pavements differ in various climatic conditions and regions. After witnessing 2016 / 2018 extreme weather events within his home state (NC), his desire to learn more about the role of pavement resilience strengthened. Along with being a concrete pavement resource for the members, design consultants and local agencies, Greg enjoys spending time with his family, traveling and rooting on his alma mater, North Carolina State University (BS CE). - 46 - Design Stiffer Pavement Systems… Stiffer Pavements are less impacted by subgrade strength loss and recover faster (stiffer = concrete, cement stabilized bases, increased asphalt thickness) Pe rf or m an ce Time (years) Rigid System Flexible System Early Rehab Time the road is submerged / not passable 1) Lower drop in performance (Both Short and long term) 2) Quicker opening 3) Shorter recovery time Design Life 4) Less Secondary impacts (less dependence on subgrade / base strength) Federal Aviation Administration Advisory Circular 150/5320‐6G (June 2021) 2.3.9 Subgrade Support for Pavement Design 2.3.9.4 The FAA recommends selecting a subgrade strength value for design that is one standard deviation (sample) below the mean of laboratory tests. Use a value for design that reflects the expected long‐ term subgrade support. Document and support the value used in the geotechnical report. - 48 - ACTIVITIES THAT CAN BE USED TO “HARDEN THE PAVEMENT SYSTEM” Modify “Design Standards” to be based on weakened subgrade condition Almost All Pavement Designs in Australia are based on soaked subgrade conditions 8/13/2021 13 Year to Year, the trends and RISK are there… TS / H1 Elsa impacts early July | |
| Innovation with Concrete Overlays for DOTs and Municipalities | 👤 Steve Tritsch 👤 Gordon Smith 👤 Charles Stuart | Concrete Pavement Technology Tuesday | 2021 |
| 2021-07-13 | 7/13/2021 1 Guide to Concrete Overlays, 4th Edition Concrete Overlays – What’s New and Different Steven L. Tritsch, P.E. stritsch@iastate.edu July 13, 2021 Things to Cover • Chapter 1 Introduction • Chapter 2 Evaluation of Existing Pavements and Selection of Concrete Overlay Options • Chapter 3 Overview of Concrete Overlay Design • Chapter 4 Concrete Overlays on Existing Asphalt- Surfaced Roads • Chapter 5 Concrete Overlays on Existing Concrete Pavements • Chapter 6 Materials and Mixtures • Chapter 7 Plan Development • Chapter 8 Construction of Concrete Overlays • Appendices • History of Concrete Overlays in the United States 2 Chapter 1 Introduction 3 Chapter 2 Evaluation of Existing Pavements and Selection of Concrete Overlay Options • Determine the existing pavement type and condition • Make a preliminary determination of the existing typical section layers and thicknesses • Conduct an on-site review and evaluation • Determine the need for milling and accommodating adjustments of the profile grade • Validate the existing pavement condition – Coring and material testing • Determine the feasibility of a concrete overlay and the appropriate overlay option 4 7/13/2021 2 Chapter 3 Overview of Concrete Overlay Design Four common procedures for designing concrete overlays are listed below: • AASHTOWare Pavement ME Design • ACPA Pavement Designer • University of Pittsburgh’s BCOA-ME • University of Pittsburgh’s UBOL Design v1.0 5 Chapter 4 Concrete Overlays on Existing Asphalt-Surfaced Roads 6 I-35 OK 2004 SH 13 IA 2002 Chapter 5 Concrete Overlays on Existing Concrete Pavements 7 2007 before overlay in 2008 Route D, MO in 2020 Milling 2” of concrete 3 ½” on I-70, KS in 2013 Chapter 6 Materials and Mixtures Concrete overlays are constructed with conventional concrete paving materials, which include cement, supplementary cementitious materials (SCMs), aggregate, water, chemical admixtures, dowel bars, tie bars, continuous steel reinforcing (for CRCP overlays), curing compounds, and joint fillers or sealants. They can also include macrofibers as well as separation layers. 8 7/13/2021 3 Chapter 7 Plan Development • Construction drawings for concrete overlays do not need to be complex. The location, geometric features, and maintenance of traffic requirements of a given overlay project should dictate the level of design detail that is required in the plans. • For decades, asphalt overlay projects on rural roads have been successfully designed and constructed from a set of drawings consisting of a limited number of sheets. This same approach can be used for concrete overlays. 9 Chapter 8 Construction of Concrete Overlays The total construction time required for a concrete overlay project is significantly shorter than that required for a roadway reconstruction project because limited quantities of earthwork and base materials are needed (or not needed at all) and concrete placement normally proceeds at a much faster pace. Additionally, weather has fewer potential impacts on construction schedules. Projects can be opened to traffic within a short period of time with adequate planning, expedited staging, and efficient operations. 10 SH 13 CO 2016 I-44 MO 2009 Uniontown PA 2010 Included • Appendix A Fundamentals of Concrete Overlay Design • Appendix B Continuously Reinforced Concrete Pavement Overlays • Appendix C Concrete on Concrete-Bonded Overlays • Appendix D Staging Sequence Diagrams for Various Traffic Control Scenarios • 93 References, 96 Figures, and 14 Tables • Interactive pdf with links to other parts of the guide as well as pertinent documents. 11 History of Concrete Overlays in the United States 12 Case history #3 • CR 56 near Peru, Illinois • 1974 5” w/thickened edge 7” • Concrete on Asphalt – U • Estimated ESALs 12.5 million 5 projects COA – B 2 projects COA – U 2 projects COA – B composite 2 projects COA – U composite 2 projects COC – B 2 projects COC – U 2 projects COC – U CRCP 7/13/2021 4 Unbonded – 78% Bonded 22% 13 National Concrete Overlay Explorer (ACPA 2020) Thank you for your time 14 www/cptechcenter.org Carroll Street Macomb, IL 2013 Grand Strand Airport N Myrtle Beach, SC 2018 I-69 IN 1986 US 59 IA 2014 7/13/2021 1 Value Proposition/Proven Technology Concrete Overlays – What’s New and Different Tuesday, July 13, 2021 Gordon L. Smith, P.E. glsmith@iastate.edu Concrete Overlays: Today’s Talking Points • The Challenges • The Value Proposition • Addressing Barriers to Implementation • Getting Started • Case Histories • Resources 2 The Challenge to Pavement Owners • Existing infrastructure is continually deteriorating • Weather • Traffic • Demands are increasing • Traffic • Ride quality • Continuous access • Funding is decreasing • Maintenance costs often exceed Agency revenue 3 Maintaining Existing Pavements • We can toss them out and start again • A long term solution • Creates a disposal headache • Takes energy to move them out of the way • Takes time = traffic delays 7/13/2021 2 Maintaining Existing Pavements • We can patch them – buy a few years • Limited materials usage, energy and traffic impact • Effective • A shorter term solution Maintaining Existing Pavements • We can overlay them with concrete • Use existing equity • Minimize sustainability impacts • Long term solution • Lower life cycle cost • Elevations / connections are tricky Another Tool in the Toolbox • Concrete Overlays - Concrete placed over an existing paved surface to: • Extend life • Restore ride • Increase capacity 7 Concrete Overlays 8 Concrete on Asphalt Concrete on Concrete 7/13/2021 3 Proven Applications for Concrete Overlays Urban Arterials Rural Primary/Interstates Urban Freeway/InterstatesIntersections Rural Secondary Roads Airport Runways Parking Lots The Value Proposition • Costs • Environmental impacts • Resiliency • Effectiveness 10 ACPA Costs • Initial costs depend on • Competition • Local contractor experience • Local materials availability • Can be competitive with other solutions • Annual ownership costs are reduced • Longer life • Less maintenance • Overall network condition is raised 11 Environmental Impacts • Long life and low maintenance reduces environmental impacts • Improved fuel efficiency • Low albedo, reducing the heat island effect • Concrete is 100% recyclable • May absorb CO2 12 MIT CSHub 7/13/2021 4 Resiliency • Flooding saturates and weakens a pavement’s underlying foundation • Concrete overlays reduce the stress at the top of the asphalt layer • Sensitivity to softening is reduced 13 FHWA Effectiveness • A long history • As early as 1901 • A number of overlays built in the 1970s remain in service today 14 Effectiveness • Performance • Depends on thickness • Condition of existing layer • Detailing • Life can be up to 35 years 15 Effectiveness • Versatility • Can be applied to all surface types • Many degrees of distress can be accommodated • Used for a range of applications: • Roadways • Streets and Intersections • Parking lots • Airfields 16 7/13/2021 5 Effectiveness • Rapid Construction • Depends on preparation effort • Placement is fast with thinner sections 17 SGL[4 Effectiveness • Traffic Impact • Maintenance of traffic is simpler than reconstruction • Construction under traffic is possible • Early opening is possible (Maturity) 18 Effectiveness • New technologies improve everything • New design methodologies • Performance Engineered Mixtures (PEM) • Reduced CO2 footprint • Stringless machine control • Larger paving machines • Vibrator monitoring • Real time smoothness • Fiber reinforcement 19 Effectiveness • Safety • Reduced frequency of closures 20 7/13/2021 6 Effectiveness • Efficiency • Similar practices to conventional concrete paving • Simple plan sets are possible • Guide specifications available • Guidance documents available 21 Challenges • Exclusion from Agency Project Management System • Most PMS reflect local institutional experience and practices • Innovation is hard • Alternative solutions are not considered • Change needs to come from above 22 Challenges • Technical Experience • Lack of technical competency of SHA staff can be a concern. • Building technical competency is not difficult. • Help is available from CP Tech Center and recently, the FHWA EDC-6 program • Lack of concrete paving contractors with experience may also be a concern. • Help is available from ACPA 23 Challenges • Agency Focus on Surface Condition Only • Pressure to “cover as much as possible” • Unsustainable short term fixes • Ignores traffic disruptions and safety impacts • Diamond grinding can be a cost-effective surface treatment 24 7/13/2021 7 Challenges • Difficulty Identifying Candidate Projects • Suitable overlay type for the existing system • Elevation issues • Bridges • Connections • Services • A range of solutions are available 25 Challenges • Traffic Management/Detour Options • An overlay can be built faster than a reconstruct • Construction under traffic is possible • Experience has proven that communication and planning are the key… 26 Challenges • Perceived Federal Funding Limitations • Concrete overlays can be considered preventative maintenance, qualifying them for use of federal aid funds. 27 Getting Started • Start with a simple project • Get help • Evaluate performance • Build competency and confidence • Integrate the process into a mix of fixes 28 7/13/2021 8 The Process • Identify the type of pavement to be overlaid • Assess the condition of the existing pavement • Design • Build • Repeat 29 apps.acpa.org CP Tech Technical Guides on Overlays 7/19/2021 1 Advancing the Use of Concrete Overlays in California Charles Stuart, SWCPA, cstuart@swcpa.org July 13, 2021 Implementation on of concrete overlays in California OUR EXCEPTIONAL COLLABORATIVE PARTNERS 2 20122011 2013 2014 2015 CP Tech Center offers support to Caltrans SWCPA and CNCA begin outreach on overlays Caltrans shows first real interest on a project 2016 2017 2018 2019 2020 2021 2022 First high‐traffic JPCP concrete overlay on asphalt bid for I‐10 Caltrans HQ asks CP Tech Center for support and initiate's research at UCPRC First workshops and site visits, university research begins First CRCP overlays bid for I‐8 250,000 CY 19,000 CY 250,000 CY 110,000 CY 150,000 CY First low‐traffic concrete overlays bid for SR 113 and SR 247 Concrete Overlays: Timeline for implementation 3 20122011 2013 2014 2015 CP Tech Center offers support to Caltrans SWCPA and CNCA begin outreach on overlays Caltrans shows first real interest on a project 2016 2017 2018 2019 2020 2021 2022 Concrete Overlays: Timeline for implementation First high‐traffic JPCP concrete overlay on asphalt bid for I‐10 Caltrans HQ asks CP Tech Center for support and initiate's research at UCPRC First workshops and site visits, university research begins First CRCP overlays bid for I‐8 250,000 CY 19,000 CY 250,000 CY 110,000 CY 150,000 CY First low‐traffic concrete overlays bid for SR 113 and SR 247 4 7/19/2021 2 Caltrans Concrete Overlay Projects, 1992‐2021 SR 113, JPCP‐COA, Low‐ traffic, 12,700 CY 2 1 5 6 4 1 I‐80, JPCP‐COC, 12 projects, 250,000 CY 3 SR 14, CRCP‐COC, 12 projects, 110,000 CY SR 247, CRCP‐COA, Low traffic, 6,400 CY I‐10, JPCP‐COA, 3 projects, 500,000 CY Dist rict Rt. Pavement Type Size (CY) D3 I‐80 JPCP‐COC 540,000 D3 SR‐ 113 JPCP‐COA, Low‐traffic 12,700 D8 SR‐ 247 JPCP‐COA, Low traffic 6,400 D11 I‐8 CRCP‐COC 250,000 D9 SR‐14 CRCP‐COC 110,000 D8 I‐10 JPCP‐COA 500,000 1 2 3 4 5 6 5 6 I‐80, Sierra Nevada Mountains • Bid dates: 1992‐2010 • Caltrans District 3 • 12 projects • 540,000 CY of JPCP‐COC 6 1 1992‐2010 Concrete Overlay on Concrete (COC) projects • Caltrans District 3 • I‐80, Sierra Nevada Mountains • 12 projects • 540,000 CY of JPCP‐COC TYPICAL CROSS SECTION 1 7 I‐80, Sierra Nevada Mountains • Bid dates: 1992‐2010 • Caltrans District 3 • 12 projects • 540,000 CY of JPCP‐COC 8 7/19/2021 3 9 2 SR‐113, Woodland, CA • Bid date: 2018 • Caltrans District 3 • 12,700 CY of JPCP‐COA, Low traffic • Pilot project with research aspect • 6X6x6 and 6x6x8 design 9 JOINT AND TIEBAR PLACEMENT SR‐113, Woodland, CA • Bid date: 2018 • Caltrans District 3 • 12,700 CY of JPCP‐COA, Low traffic • Pilot project with research aspect • 6X6x6 and 6x6x8 design 10 3 SR‐247, Lucerne Valley • Bid date: 2018 • Caltrans District 8 • 6,400 CY of JPCP‐COA Low traffic 11 3 12 CONCRETE OVERLAY OVER ASPHALT – TIE BAR LAYOUT 7/19/2021 4 SR‐247, Lucerne Valley • Bid date: 2018 • Caltrans District 8 • 6,400 CY of JPCP‐COA Low traffic 3 13 4 I‐8, Imperial County to Arizona border • Bid dates: 2017 • Caltrans District 11 • Two projects with a total of 250,000 CY of CRCP‐COC • 130,000 CY CRCP, awarded 10/15, • 128,000 CY, CRCP, awarded 11/15 • 90,000 CY, CRCP, awarded 11/15 • 170,000 CY, CRCP Overlay, awarded 1/17 • 84,000 CY, CRCP Overlay, awarded 2/17 14 4 15 5 SR‐14, Mojave, CA • Bid date: 2018 • Caltrans District 9 • 110,000 CY of CRCP‐COC 16 7/19/2021 5 5 SR‐14, Mojave, CA • Bid date: 2018 • Caltrans District 9 • 110,000 CY of CRCP‐COC 17 I‐10, Desert Center to Blythe • Bid dates: 2021‐22 • Caltrans District 8 • Three projects with a total of 500,000 CY of JPCP‐COA 6 18 Concrete Overlays: Next steps 19 • Continue supporting Caltrans through training • Work with our partners through the EDC‐6 TOPS initiative • Develop standard structural sections for low traffic concrete overlays • Analyze the sustainability benefits of concrete overlays • Improve initial IRI smoothness and construction quality • Communicate clearly and frequently about the many benefits • Be thankful for exceptional collaborative partners! Thank You! 20 Charles Stuart, Southwest Concrete Pavement Association cstuart@swcpa.org Overlays Webinar – Questions and Answers The questions submitted during the webinar follow with answers that our speakers have provided. 1. This month's FHWA Innovator mentions the potential resiliency benefits of using overlays. Will the new (4’th edition) guide highlight some of the benefits how a concrete overlay improves a pavement's (flood) resiliency? https://www.fhwa.dot.gov/innovation/innovator/issue85/page_01.html, North Carolina Yes. That is covered in the Asset Management through the “Use of Concrete Overlays” section in Chapter 1. 2. How soon can you get traffic on a concrete overlay on asphalt in a parking lot? Ohio The “Guide to Concrete Overlays of Asphalt Parking Lots” (https://my.nrmca.org/Main/ItemDetail?iProductCode=2PPCO) discusses concrete opening parameters noting that “Many concrete overlays can be opened to traffic within 24 hours of placement. Nondestructive strength indicators, like maturity testing, enable engineers to take advantage of this benefit. Opening would also be dependent on mix design and weather conditions. 3. Are there projects where concrete is placed over FDR - is that considered an overlay or new construction? Maryland Yes, there are several instances where concrete has been placed on top of FDR. The classification of that pavement structure as new construction or overlay may not yet be determined. 4. Has the Illinois DOT done any concrete overlays and if so in what highway districts, Iowa Yes. Several of the 114 projects listed in The National Concrete Overlay Explorer were constructed by the Illinois DOT, ranging from Interstate pavements to two lane roadways. http://overlays.acpa.org/webapps/overlayexplorer/index.html 5. CALTRANS- what is the typical slab length? Joint width (seal/unsealed)? Florida Caltrans uses a standard slab length of 14 feet for their JPCP overlays when used on high-traffic interstate locations. For low-traffic concrete overlays, the thickness has been reduced to about 6 inches and the joint spacing changed to about 6 feet by 6 feet. We have not sealed the concrete overlays for the low-traffic applications. For high- traffic, instead of “sealing” Caltrans has moved towards single cut of the joints about 3/16 to1/4 inch wide and filling with hot-pour for projects in high desert and high mountain regions. Concrete overlays in other regions do not get sealed or filled joints. 6. Can use of precast concrete slabs be considered as overlay (bonded and unbonded)? Florida We have not considered precast concrete slabs as concrete overlays in California. We’ve done lots of precast pavement but it’s all full-depth on a base. https://www.fhwa.dot.gov/innovation/innovator/issue85/page_01.html http://overlays.acpa.org/webapps/overlayexplorer/index.html 7. Is parking concrete pavement design different from roadway design? New York Parking lot design involves different load spectrums and jointing patterns dependent on the staging for construction or traffic control. The ACPA Pavementdesigner.org software, available through the ACPA website: https://www.acpa.org/expert- help/pavementdesigner-org/ provides two design methodologies that address the consideration for parking lot design. Commercial parking areas are typically designed using the ACI 330 method and/or the PCA Street Pave programs included in the Pavementdesigner.org. Intermodal parking areas can be designed using the ACPA AirPave software included as part of the Pavementdesigner,org package. Overlays Webinar – Questions and Answers | |
| Roller-Compacted Concrete for Roadway Applications | 👤 Fares Abdo 👤 Andy Johnson 👤 Chris Carwie | Concrete Pavement Technology Tuesday | 2021 |
| 2021-06-15 | Advancement in DOT Uses for RCC Webinar June 15, 2021 Fares Y. Abdo, P.E. RCC Pavement Council Co-Chair & Research Committee Chair p: 205.370.8883 fabdo@morgan-corp.com morgan-corp.com Agenda Brief Introduction Morgan Corp. The RCC Pavement Council RCC Pavements Latest Trends in RCC Pavements RCC PC Sponsored Research Example Projects of Industrial Facilities with Roadway Components Morgan Corp. www.morgan-corp.com Founded in 1945, purchased by current owners in 1971 Heavy industrial and commercial site development and RCC for pavements and dams / reservoirs RCC business added in 2008 Area of operations Offices Spartanburg, SC Charlotte, NC Savannah, GA Raleigh, NC The RCC Pavement Council Mission: To sustainably advance RCC pavements through research and promotion activities Membership: About 30 members - RCC paving contractors, materials suppliers, equipment manufacturers, and consultants Voting membership: $3000/yr Non-voting associate membership: $500/yr All volunteers – 100% of dues is invested in research and promotions Two committees, one vote per member on each committee Research Committee Promotion Committee Five members Board of Directors Although all decisions are made independent of our industry partners with whom we collaborate closely (ACPA, PCA, NRMCA, CPTech Center, etc.), ACPA has been graciously managing our finances The RCC Pavement Council Developed Resources Comprehensive website: www.rccpavementcouncil.org Promotional Videos Project performance review reports Market promotion publications Research reports Published TRB papers Example projects with a link to the RCC Explorer on ACPA’s website Helped fund and provided technical support during the development of PavementDesigner.org Exhibits at Conferences ICCP; AREMA/REMSA; ASCE Ports; NACE; DBIA; MODEX RCC Pavements Are Not New Started in industrial and military applications Now proven to be a valid option for the vast majority of pavement applications Courtesy the CPTech Center and PCA, Guide for RCC Pavements, 2010 RCC Utilization RCC utilization showed momentum mid-1980’s and started increasing rapidly since the 2000’s Preliminary reports indicate that RCC utilization is now increasing rapidly - 5 10 15 20 25 0.0 0.5 1.0 1.5 2.0 2.5 19 75 19 77 19 79 19 81 19 83 19 85 19 87 19 89 19 91 19 93 19 95 19 97 19 99 20 01 20 03 20 05 20 07 20 09 20 11 20 13 20 15 C um ulative R C C SY M ill io ns Ye ar ly R C C S Y M ill io ns RCC SY PAVED BY YEAR Yearly SY Cumulative SY RCC Mixture Ingredients Like conventional concrete Well graded combined aggregates Cementitious materials Water Chemical admixtures (if used) How is RCC Mixed? Continuous pugmill mixing plants are used on most projects: most efficient, and most consistent Other mixing machines such as revolving drum batch mixers, horizontal shaft mixers, and batch type pugmills have been used The RCC Paving Train RCC Curing RCC Pavements Latest Trends Mixture Design Cementitious content In most cases controlled by workability and surface durability not strength Minimum 450 pcy. Range for most projects is 450 to 525 pcy Nominal maximum aggregate size: ¾” max and preferably ½” Smaller top size to reduce segregation and improve surface quality Combined gradation methods: 0.45 Power Curve; Tarantula Curve On-site blending: Combining a minimum of 2 aggregates is strongly recommended. Single stockpile is not recommended and may not be permitted on some projects. RCC Pavements Latest Trends Joints Layout Follow joint layout design similar to plain undoweled conventional concrete Nominal maximum transverse joint spacing = 15 ft. Longitudinal joint spacing depends on placement width and locations of obstacles in the field of the pavement For most applications with t > 7”, pave 24 to 34 feet wide and saw cut the centerline of the pull RCC Pavements Latest Trends Compaction High density screeds should be required for density and smoothness Rolling in vibratory mode should be required RCC Pavements Latest Trends Finishing Methods Traditional RCC finish with steel drum or rubber tire rollers continues to be used by many contractors and accepted by owners Troweling or troweling and broom finishing RCC surfaces is gaining recognition Multiple finishing aid products are available to facilitate troweling RCC Pavements Ongoing Research Sponsored by the RCC Pavement Council UIUC Fellowship: Effects of Paste Content on RCC Workability and Compactability Teas A&M Fellowship: Volumetric Changes, Curling, and Warping of RCC MTSU Study: Relative Abrasion Resistance of Troweled RCC Treated with Various Finishing Aids Agenda Brief Introduction Morgan Corp. The RCC Pavement Council RCC Pavements Latest Trends in RCC Pavements RCC PC Sponsored Research Example Projects of Industrial Facilities with Roadway Components South Carolina Inland Port, Greer, SC; 2014 Duke Energy Plant Mayo Haul Rd, Roxboro, NC; 2014 Walmart DC, Mebane, NC; 2015 Walmart Southeast Import DC, Mobile, AL; 2018 HEB DC, San Antonio, TX; 2020 Thank You! Fares Y. Abdo, P.E. fabdo@morgan-corp.com 205.370.8883 www.rccpavementcouncil.org Who & Where? Introduction to AG Peltz Group, LLC Started in RCC in 1999 Managing partner very active in the field Most of key employees have 10+ years RCC experience Based in Birmingham, AL – less than 20% of work in Alabama Over 9M Square Yards of RCC Placed – Manufacturing, Distribution, Port & Intermodal, Dam, Roadways, Military Background: GDOT I-285: Life Cycle Pavement Distress Review 2004 20172017 • Owner: ALDOT • Use Type: Interstate shoulder & ramps • Year Built: 2021 • Thickness: 5” RCC • Mainline is 5’ & 10’ shoulders – Ramps with 5-16’ paving • Quantity: 128,686 SY Pavement Design Information • Material placement split between nightime and daytime depending on primary traffic flow. • Night work from at 7:00 PM to 4:00 AM and day work from 10:00 AM to 6:00 AM. $ time penalties. • Existing mainline milled and rehabbed. RCC shoulder used as travel lane during construction. • Typically 2,500-2,800 LF placed per shift. Additional Details I-59 Shoulder & Ramp Replacement Birmingham, AL I-59 Shoulder & Ramp Replacement Birmingham, AL Project covers 6 + miles of I-59 with the plant site near the midpoint. Portland Limestone Cement (EcoCem) from Lehigh is being utilized on the project. Pilot project for ALDOT and AGP. Typical schedule for night paving: Traffic Control at 7:00 PM, Milling 8:00 PM, RCC 10:00 PM. All milled areas must be filled with RCC prior to opening to traffic (i.e., interstate drop-off requirements) I-59 Shoulder & Ramp Replacement Birmingham, AL Outside shoulder paved at 10’ with sawed joints every 10’ feet. 95% density achieved through paver. RCC used for longevity and to provide structural value without getting into edge drains. I-59 Shoulder & Ramp Replacement Birmingham, AL Paver modified by AGP to place inside shoulder at a 5’ width. Daytime work allowed based on traffic flow. Start 10:00 AM and usually done with RCC paving by 7:00 PM. Road opened by 6:00 AM. I-59 Shoulder & Ramp Replacement Birmingham, AL Questions and Contact Information Chris Carwie AG Peltz Group, LLC ccarwie@agpeltz.com www.agpeltz.com www.rccpavementcouncil.org 205.335.0579 | |
| Concrete Overlays Technical Overview: A Proven Technology | 👤 Peter Taylor 👤 Gary Fick | PennDOT Concrete Overlays Webinar | 2021 |
| 2021-05-18 | 5/18/2021 1 Concrete Overlays A Proven Technology Concrete Overlays – A Proven Technology • The Challenge • The Value Proposition • Addressing Barriers to Implementation • Getting Started • Project Highlights • Resources 2 The Challenge to Pavement Owners • Existing infrastructure is continually deteriorating • Weather • Traffic • Demands are increasing • Traffic • Ride quality • Continuous access • Funding is not increasing • Maintenance costs may exceed Agency revenue 3 Maintaining Existing Pavements • We can toss them out and start again • A long term solution • Creates a disposal headache • Loose equity of existing system • Takes energy to move them out of the way • Takes time = traffic delays 5/18/2021 2 Maintaining Existing Pavements • We can patch them – buy a few years • Limited materials usage, energy and traffic impact • Short term solution Maintaining Existing Pavements • We can overlay them with concrete • Use existing equity • Minimize sustainability impacts • Long term solution • Elevations / connections are tricky Another Tool in the Toolbox • Concrete Overlays - Concrete placed over an existing surface to: • Extend life • Restore ride • Increase capacity 7 The Value Proposition • Costs • Performance • Environmental impacts • Resiliency • Effectiveness 8 ACPA 5/18/2021 3 Costs • Initial costs depend on • Competition • Local contractor experience • Local materials availability • Can be competitive with other solutions 9 Costs • Annual ownership costs are reduced • Longer life • Less maintenance • Overall network condition is raised 10 MIT CSHub Environmental Impacts • Long life and low maintenance reduces environmental impacts • Improved fuel efficiency • Low albedo, reducing the heat island effect • Concrete is 100% recyclable • May absorb CO2 11 MIT CSHub Resiliency • Flooding saturates and weakens a pavement’s foundation • Concrete overlays reduce the stress in the asphalt layer • Sensitivity to subgrade softening is reduced 12 FHWA 5/18/2021 4 Effectiveness • History • As early as 1901 • 2000 miles in service in Iowa 13 Effectiveness • Performance depends on: • Thickness • Condition of existing layer • Detailing • Can be • Unbonded from existing layer to prevent reflective damage • Bonded to make use of system in place • Life can be up to 35 years 14 Effectiveness • Versatility • Can be applied to all surface types • Many degrees of distress can be accommodated • Has been used for a range of applications • Roadways • Intersections • Parking lots • Airfields 15 Effectiveness • Rapid Construction • Depends on preparation effort required • Placement is fast with thinner sections • Productivity is less influenced by weather conditions • Traffic can be restored in a weekend 16 5/18/2021 5 Effectiveness • Traffic Impact • Maintenance of traffic is simpler than reconstruction • Construction under traffic is possible • Early opening is possible 17 Effectiveness • New technologies improve everything • New design methodologies • Performance Engineered Mixtures (PEM) • Reduced CO2 footprint • Stringless control • Large, adaptable paving machines • Vibrator monitoring • Real Time Smoothness • Maturity monitoring 18 Effectiveness • Safety • Reduced frequency of closures 19 Effectiveness • Efficiency • Similar practices to conventional concrete paving • Simple plan sets are possible • Guide specifications available • Guidance documents available • Training and troubleshooting available 20 5/18/2021 6 Challenges • Exclusion from Agency Project Management System • Most PMS reflect local institutional experience and practices • Innovation is hard • Alternative solutions are not considered • Change needs to come from above 21 Challenges • Technical Experience • Lack of technical competency of SHA staff can be a concern. • Help is available from CP Tech Center and FHWA EDC-6 program • Building technical competency is not difficult. • Lack of concrete paving contractors with experience may also be a concern. • Help is available from ACPA 22 Challenges • Agency Focus on Surface Condition Only • Pressure to “cover as much as possible” • Unsustainable short term fixes • Ignores traffic disruptions and safety impacts • Diamond grinding can be a cost-effective surface treatment 23 Challenges • Difficulty Identifying Candidate Projects • Suitable overlay type for the existing system • Elevation issues • Bridges • Connections • Services • A range of solutions are available 24 5/18/2021 7 Challenges • Traffic Management/Detour Options • An overlay can be built faster than a reconstruct • Construction under traffic is possible • Communication and planning… 25 Challenges • Perceived Federal Funding Limitations • Concrete overlays can be considered preventative maintenance, qualifying them for use of federal aid funds. 26 Getting Started • Start with a simple project • Get help • Evaluate performance • Build competency • Integrate the process into the mix of fixes 27 The Process • Identify the type of pavement to be overlaid • Assess the condition of the existing pavement • Design • Build • Repeat 28 5/18/2021 8 Project Highlights 29 State/Route Year Constructed Existing Pavement & Overlay Type Functional Classifications Traffic Volume Maintenance of Traffic Strategy North Carolina/I-77 2007-2008 COC-U on CRCP Interstate 31,500 AADT with 25% trucks Maintain two-lanes each direction Colorado/SH13 2016 COA-B on HMA Primary Hwy 1,400 AADT with 20% trucks 24-hour pilot car Oklahoma/SH51 2016 COA-B on HMA Primary Hwy - Closed to through traffic Iowa/County Route S10/S14 2009 COA-U on HMA County road - Closed to through traffic Kansas/City of Salina 2012 COA-U on composite pavement Urban intersection 32,000 Staged construction maintaining traffic Project Highights Yadkin County, NC I-77 • Existing CRCP circa 1964 • Punchouts • Ruptured Steel • Faulting at cracks • Design-build delivery method 30 Project Highights Yadkin County, NC I-77 • Median detour with limited duration of one-lane operation • 11-day closure limit for ramps • 11 inch JPCP on 1 ½ inch asphalt separation layer • Bridges were raised to match overlay elevation • 100% grind 31 Project Highights Moffat County, CO SH-13 • Existing Asphalt • Profile milled to optimize volume of concrete and final smoothness • 6 inch thick JPCP, 6 ft x 6 ft slabs • Alternate bid 32 5/18/2021 9 Project Highights Moffat County, CO SH-13 • Two-way traffic maintained with pilot car • Project length = 6 miles • Average IRI < 45 in/mile 33 Project Highights Blaine County, OK SH-51 • Asphalt bids rejected twice Overbudget • 5 inch thick fiber reinforced JPCP, 6 ft x 7 ½ ft slabs • Profile milled • Roadway closed to through traffic (5 ½ mile project length) 34 Project Highights Blaine County, OK SH-51 • Constructed in sections to allow access for adjacent property owners • Project completed less than 90 days after bids were opened • Drainage structures extended to accommodate a widened paved roadway 35 Project Highights Worth County, IA S10/S141 • Alternate bid • 4 inch thick JPCP, 6 ft x 6 ft slabs • 23 mile long project • Plan set was 10 pages 36 5/18/2021 10 Project Highights Worth County, IA S10/S141 • No preoverlay repairs • Roadway closed to through traffic • Entire project opened to unrestricted traffic in 110 calendar days 37 Project Highights Saline County, KS Crawford and Ohio Streets • Busiest intersection in Salina, KS > 30,000 ADT • Partial depth milling • 8 inch thick JPCP, 12 ft x 12 ft slabs 38 Project Highights Saline County, KS Crawford and Ohio Streets • Staged construction kept the intersection open • Completed in 45 days 39 Before After Resources 5/18/2021 11 | |
| An Introduction to Recycled Concrete Aggregate (RCA) | 👤 Tara Cavalline 👤 Matt Fonte | Concrete Pavement Technology Tuesday Webinar | 2021 |
| 2021-05-11 | 5/11/2021 1 Recycled Concrete Aggregates (RCA): The Basics Tara L. Cavalline, PhD, PE University of North Carolina at Charlotte May 11, 2021 Acknowledgments • Mark B. Snyder – Pavement Engineering and Research Consultants (PERC), LLC • Peter Taylor, Iowa State University, CP Tech Center Director • Gary Fick, The Transtec Group • Tom Cackler – Woodland Consulting, Inc. • Dale Harrington, Snyder & Associates • American Concrete Pavement Association • Federal Highway Administration • Photo Contributors Photo: Gary Fick, Transtec Concrete recycling is not new... • Post WW 2 Europe – concrete recycling performed extensively • First major use in U.S. pavement construction was on Historic US Route 66 in Illinois in the 1940s • Increased concrete recycling in US in 1970s/80s (environmental initiatives) Today: • RCA primarily used in unbound applications (base/fill) • Over 100 pavement projects constructed in United States using RCA in concrete as partial or full replacement for coarse aggregate, fine aggregate or both • Use driven by: • Need for more sustainable infrastructure • Demand for alternative aggregate sources • Cost savings Photo: Dwayne Stenlund, MnDOT Use of RCA in Pavement Applications • Concrete pavement • Conventional or 2-lift • Asphalt pavement • Aggregate shoulder • Subbase • Unbound or stabilized • Drainage layer • Filter material • Fill material Annual RCA Production 2018 (USEPA 2020) 405.2 million tons Beneficial Reuse 2018 (USEPA 2020) 334.0 million tons Disposal 2018 (USEPA 2020) 71.2 million tons 5/11/2021 2 Why recycle concrete and reuse RCA? • Environmental benefits • Conserve natural resources (aggregates, fuel, landfill space) • Reduce greenhouse gas emissions • Economic benefits • Lower costs – materials, disposal, hauling • Can reduce project competition time • Can provide performance enhancements (foundation layers) • Social (community benefits) • Can reduce number of construction vehicles on roadways Quantifying Sustainability • Beltline Highway – Madison, WI • 1.5 mile segment reconstructed using a variety of recycled materials • RCA used in base course or embankment fill • 9,870 CY of RCA from onsite material utilized, crushed and graded onsite • Additional RCA sourced from offsite • Source concrete qualified for use using WisDOT’s specifications • Require AASHTO T 96 abrasion testing for off-site materials Photo: Steven Theisen, WisDOT Quantifying Sustainability • Beltline Highway – Madison, WI • LCCA → cost savings of approx. $130,000 at ini al construc on from RCA use Photo: Emily Bloom, UW-Madison • LCA → life me environmental impact reductions of: • Energy use (13% reduction), • Water consumption (12% reduction) • CO2 emissions (13% reduction) • Hazardous waste (9% reduction) • LCA was performed with PaLATE tool (Horvath 2007, detailed in Bloom et al. 2016) The Recycling Process • Evaluate source concrete – quality, contaminants • Remove large amounts undesirable material (asphalt overlays/patching) • Break and remove existing pavement • Remove steel • Crush and size • RCA can be produced: • On-site with a mobile crusher • typically base and fill applications • On-site with a stationary crusher • RCA for use in new concrete • Off-site using a stationary facility • urban areas, typically crush C&D waste from multiple projects Photo: Gary Fick, Transtec Photos: ACPA (2009) 5/11/2021 3 On-site processing with mobile crushing equipment 9 Photo: Manatt’s Photo: Kevin Merryman, Iowa DOT Stationary plants – off-site or on-site processing 10Photo: Gary Fick, Transtec Use front-end loaders and dump trucks for removal and transport Photo: John Cappello, RJ Smith Off-site plant Photo: ACPA (2009) On-site plant or The Recycling Process • Crushers • Jaw, cone, impact • Primary, secondary, sometimes tertiary • Type and size of crusher determines: • quantity of RCA produced • gradation of RCA produced • quantity of fines generated • Crushing of “clean” quality concrete can give 1-2% material finer than No. 200 sieve (Fick 2017) From ACPA (2009) The Recycling Process • Screening after primary crusher to remove oversized material • Beneficiation –to remove joint sealant, dust, other light materials • Air blowing • Washing • Heavy media separation • Screening • Stockpiling Photo: Tom Cackler Photo: Gary Fick, Transtec Photo: Gary Fick, Transtec 5/11/2021 4 Characteristics of RCA • RCA are composites – natural coarse aggregate + adhered mortar • Differences in performance driven by mortar fraction • Mortar makes RCA • more porous • lower unit weight • higher abrasion loss • Smaller sized particles = typically more mortar • Volume of mortar fraction • quality of source concrete • crusher type • particle size being produced • Often more angular than virgin aggregates, rougher texturePhotos: Miras Mamirov, Univ. of Nebraska Characterization Tests for RCA • Similar to virgin aggregates • Gradation, abrasion, susceptibility to ASR/D-cracking • Many agencies require RCA meet same quality requirements as virgin aggregates • Some agencies have additional requirements for RCA • particularly from non-agency sources • limits on contaminants and potentially deleterious substances • AASHTO M 319 “Standard Specification for Reclaimed Concrete Aggregate for Unbound Soil-Aggregate Base Course.” • ACPA (2009) provides recommended limits on contaminants • Sulfate soundness tests should not be used for RCA (paste interferes with results) • Alternative sulfate soundness tests in AASHTO M 319. Typical Characteristics of RCA Property Natural Aggregate* RCA* Shape and texture Well-rounded, smooth (gravel) to angular and rough (crushed rock) Angular with rough surface Absorption capacity (%) 0.8 – 3.7 3.7 – 8.7 Specific gravity 2.4 – 2.9 2.1 – 2.4 L.A. Abrasion Test mass loss (%) 15 – 30 20 – 45 Sodium sulfate soundness test mass loss (%) 7 - 21 18 – 59 Magnesium sulfate soundness test mass loss (%) 4 - 7 1 – 9 Chloride content (lb/yd3) 0 – 2 1 - 12 * Data for are for as-produced material, including both fine and coarse material. From ACPA (2009). Unbound uses of RCA • Unstabilized base and fill material • Most common application for RCA in United States • 38+ of 44 states using RCA • Some states believe RCA outperforms virgin aggregate as an unstabilized subbase • Secondary cementing from exposed cement in crushed RCA • Some level of contaminant material is tolerable • 2016 RCA benchmarking survey (Cackler 2018) Photo: Tom Cackler 48.3 13.7 10.8 0.7 0 0 10 20 30 40 50 60 Subbases & bases Granular shoulders Embankment and backfill Erosion control In new concrete Percent of Projects 5/11/2021 5 Influence of RCA on Unbound Applications • Potential for improved performance of RCA compared to virgin aggregates • RCA particles tend to be more angular, rough-textured • Potential for re-cementation of particles (particularly fines) can improve stability • Literature appears to have no reports of pavement performance problems related to structural deficiencies in properly designed/constructed RCA bases Benefits of on-grade recycling (Fick 2017): No hauling required significant cost savings reduced exposure to traffic Photo: Gary Fick, Transtec Potential drainage issues • RCA used successfully in dense-graded undrained foundation layers and fill • Can have precipitate formation in drainable bases, drain-pipe backfill, and dense-graded base layers that carry water to pavement drain systems • “Calcareous tufa” – crushed concrete dust and calcium carbonate precipitate • Can clog fabrics and form deposits, but often do not completely prevent discharge flow • Often occurs early in pavement life, and rate of accumulation dissipates. Photos: PennDOT Preventing drainage structure clogging Typical edge drain piping (ACPA 2009) Typical daylighted subbase (ACPA 2009) • Minimize use of RCA fines • Blend RCA and virgin materials • Use largest practical RCA particle sizes • Wash the RCA to reduce insoluble residue (crusher dust) deposits • Use high-permittivity fabric • Wrap trench, not pipe • Consider daylighted subbase • Stabilize the base Cement-stabilized and lean concrete bases • Stabilization helps to prevent migration of crusher fines, mitigates high pH runoff • Physical and mechanical properties of the RCA must be considered in the design and production • RCA used in lean concrete base on I-710 in Los Angeles, CA • RCA produced from existing concrete pavement used to provide 100% coarse and fine aggregate Photo: Michael Roe, Flatiron Notable use: ATL airport 6 inch CTB with RCA under one runway, multiple taxiways From Saeed et al. (2016) 5/11/2021 6 New Concrete Mixtures • RCA can be (and has been) used as the primary or sole aggregate source in new concrete pavements • Can also be used as partial substitute for virgin fine or coarse aggregate • 1995 IH 10 project – Houston, TX • CRCP with 100% RCA (fine & coarse aggregates), still in service • RCA commonly used in the lower lift of two-lift concrete pavements in Europe Photo: Georgene Geary, GGfGA Concrete shoulders using RCA on I-16 in Georgia IH 10 in Houston, TX (2013) Photo: Andy Naranjo, TxDOT Influence of RCA on Fresh Concrete Properties • RCA concrete can be batched, mixed, transported, and placed using the same methods as conventional concrete. • Differences in RCA from natural aggregate cause changes in concrete properties Property/Characteristic Range of Expected Changes from Similar Mixtures using Virgin Aggregates Coarse RCA Only Coarse and Fine RCA Water demand Greater Much greater Air void system Similar Increased (reported air content will include air in the source concrete paste) Unit weight Slightly lower Lower Finishability Slightly more difficult More difficult Bleeding Slightly less Less Finishing characteristics Similar May be harsher to finish Setting time May be accelerated May be accelerated From FHWA 2007, ACI 2001 Mitigating reduced workability 1) Select and use crushing equipment and operating practices that decrease dust and reduce angularity of RCA 2) Maintain high moisture content of RCA prior to batching using sprinklers 3) Adjust mixture proportions to improve workability • increase paste content • increase both water and cementitious materials while maintaining w/cm ratio • use SCMs • research has suggested water demand of RCA concrete can be reduced by 12.5% with use of fly ash at 20% replacement with a superplasticizers • limit use of RCA as fine aggregate • ACPA (2009) recommends no more than 30% replacement rate Other Fresh Concrete Properties • Air void system • RCA concrete includes air void system of mortar fraction of RCA • “clean” RCA does not significantly influence performance of air entraining admixtures • Pressure method is sensitive to porosity – use aggregate correction factor or volumetric air content for RCA with high absorption • Unit weight • Tends to be 10-15% lower than conventional concrete • Bleeding/Finishability • Bleeding often reduced • If mechanical methods used, finishability not significantly affected. • Setting time • Can be 30-60 minutes shorter than conventional mixtures (Obla et al. 2007) 5/11/2021 7 Influence of RCA on Hardened Concrete Properties • RCA successfully used to produce concrete with adequate mechanical properties and good durability • Hardened properties will be influenced by RCA characteristics Property RCA used as Coarse Aggregate RCA used as Coarse and Fine Aggregate Potential Adjustments Compressive strength 0% to 24% less 15% to 40% less Reduce w/cm ratio Tensile strength 0% to 10% less 10% to 20% less Reduce w/cm ratio Strength variation Slightly greater Slightly greater Increase average strength compared to specified strength Modulus of elasticity 10% to 33% less 25% to 40% less This may be considered a benefit with regard to cracking of slabs on grade Specific gravity 0% to 10% lower 5% to 15% lower None recommended CTE 0% to 30% greater 0% to 30% greater Reduce panel sizes Drying shrinkage 20% to 50% greater 70% to 100% greater Reduce panel sizes Creep 30% to 60% greater 30% to 60% greater Typically not an issue in pavement applications Bond strength Similar to conventional concrete, or slightly less Similar to conventional concrete, or slightly less None recommended Permeability 0% to 500% greater 0% to 500% greater Reduce w/cm ratio From FHWA 2007, ACI 2001, Hansen 1986 Mitigating Impacts of RCA on Concrete Properties • RCA can reduce strength • Adjust (lower) the w/cm ratio while using water reducing admixtures to achieve the desired workability • Prewet the RCA – supports enhanced hydration of residual cement and supports internal curing benefits • Use RCA as only a fraction of the natural aggregate • Try to reduce variability of the source concrete • RCA can increase drying shrinkage • Reduce the paste content • Lower the w/cm ratio • Use SCMs Mitigating Impacts of RCA on Concrete Durability • RCA can increase permeability • RCA contains an interfacial transition zone (ITZ) • Using RCA in new concrete adds another ITZ • Use higher quality source concrete • Lower the w/cm ratio • Use RCA as only a fraction of the natural aggregate • RCA can decrease freeze-thaw resistance • Use known sources of RCA with acceptable entrained air void systems • Ensure adequate air entraining admixture used for new concrete • Abrasion resistance – depends on quality of source concrete aggregates • Use source concrete with good performance • If virgin aggregates in source concrete were not associated with skid resistance issues, the RCA concrete will likely not have issues Mitigating Impacts of RCA on Concrete Durability • Alkali-Aggregate Reactivity • Susceptibility of RCA concrete to AAR depends on remaining reactivity of aggregates in the source concrete • Crushing process may also result in exposure of new unreacted or partially reacted material in the RCA • Follow AASHTO R 80 protocol for assessing risk of alkali-silica reactivity (ASR) • Conventional AAR mitigation approaches can be used • SCMs and lithium compounds • Blending of AAR-susceptible RCA with non-reactive aggregates • D-cracking • Susceptibility of RCA concrete to D-cracking depends on source concrete’s aggregates • May be reduced since new concrete contains a lower volume of original aggregate • Certain pavement projects constructed with RCA susceptible to ASR and D-cracking have showed acceptable field performance (Snyder et al. 2018, Zeller 2016) 5/11/2021 8 Use of RCA in Concrete Mixtures • Recycling Concrete Pavement Materials: Practitioners Reference Guide (2018) • ACPA EB043P - Recycling Concrete Pavements • NRMCA Report - Crushed Returned Concrete as Aggregates for New Concrete (2007) • AASHTO M319, MP16. • U.S. FHWA TA 5040.37 • ASTM, ISO, (BS) EN and other standards Mixture Proportioning Approaches for RCA Concrete • Direct replacement method – treats RCA as conventional aggregate • Absolute volume method (ACI 211, ACI 325) used successfully for many projects • New methods recently developed specifically for RCA • Equivalent mortar volume method (Fathifazl et al. 2009) • Ensures mortar content of RCA mixture is equal to that of the conventional mixture • Empirical method (Hu et. al 2013) • Nomograph-based procedure • NJIT method (Adams and Jayasuriya 2019) • Developed using models produced from statistical analysis of more than 100 published studies on RCA concrete • University of Nebraska method (Mamirov et al. 2021) • Uses optimized particle packing models, then a minimum excess paste-to-aggregate ratio Guidance – Recent! 2018 • Ch. 1: Introduction to Concrete Pavement Recycling • Ch. 2: Economics and Sustainability • Ch. 3: Project Selection and Scoping • Ch. 4: Using RCA in Pavement Base Products • Ch. 5: Using RCA in Unbound Aggregate Shoulders • Ch. 6: Using RCA in Concrete Paving Mixtures • Ch. 7: Mitigating Environmental Concerns 92 pages of useful technical info, many case studies, and up-to-date implementation guidance Ch. 3 Project Selection and Scoping • Includes checklist of considerations for use of RCA in different applications • Materials considerations • Production considerations • Other considerations 32 Structured around a flowchart showing typical project selection and scoping process 5/11/2021 9 Ch. 3 Project Selection and Scoping Checklist of considerations for use of RCA in different applications 33 RCA use Materials considerations Production Considerations Other considerations New RCA concrete and stabilized base materials • Sources • Specifications • Processing options • Hauling • Crusher types • Production rates/storage • QA/QC • Residuals management • Project staging • Costs • Environmental considerations • Permitting • Public perception Unbound bases and drainage layers Filter material around drainage structures Fill (beneficial reuse of fines) not in pavement structure ! Highly simplified table shown here ! See Reference Guide for all details… Guidance – Coming Soon • Use of RCA in Concrete Paving Mixtures • Use of Construction Byproducts in Concrete Paving Projects • RCA and RCA fines • Discusses use in bound/unbound bases, fills, concrete • ACI 555 • Reuse of Hardened Concrete • Use of Recycled Concrete Aggregate in Unbound Applications References • Adams, M.P. and Jayasuriya, A. (2019). “Guideline Development for Use of Recycled Aggregates in New Concrete.” Final Report, ACI CRC 18.517. • Fathifazl, G., Abbas, A. G., Razqpur, A.G., Isgor, O.B., Fournier, B., and Foo, S. (2009). New Mixture Proportioning Method for Concrete Made with Coarse Recycled Concrete Aggregate. Journal of Materials in Civil Engineering, 21(10), 601–611. • Mamirov, M., Hu., J., and Kim, Y. (2021, in press). “Effective Reduction of Cement Content in Pavement Concrete Mixtures Based on Theoretical and Experimental Particle Packing Methods.” Journal of Materials in Civil Engineering. 10.1061/(ASCE)MT.1943-5533.0003890. • Snyder, M. B., Cavalline, T. L., Fick, G., Taylor, G., and Gross, J. 2018. Recycling Concrete Pavement Materials: A Practitioner’s Reference Guide. National Concrete Pavement Technology Center, Iowa State University. Ames, IA. https://intrans.iastate.edu/app/uploads/2018/09/RCA_practioner_guide_w_cvr.pdf 5/11/2021 1 Recycled Concrete Aggregates Matt Fonte Concrete Operations Manager Castle Rock Construction Company (CRCC) •At the end of 2021: •~ 2,000,000 SY of concrete pavement with RCA •~ 500,000 CY of RCA concrete produced •~ 150,000 Tons of RCA •~ $1,500,000 saving on material alone CRCC’s Recent History with RCA Why CRCC uses Recycled Concrete for Aggregates • More competitive at bid time • There is a large cost savings to the owner • Improves our quality • We produce smoother pavements using RCA • Recycling is the responsible way to conserve our natural resources Aggregate Qualifications • RCA should be classified to meet C33 requirements • Consideration should be given to the following test. • Magnesium sulfate soundness test • Light weight particles test • LA abrasion test. 5/11/2021 2 What about ASR? • Can you use concrete with known ASR as an RCA? Yes • Will Type F Fly Ash Mitigate ASR? Yes The Crushers Closed Circuit Cone Crusher Open Circuit Jaw Crusher Recycled Concrete Road Base 1 ½ “ Recycled Concrete Aggregate Stockpiles & Segregation Wetting The Aggregates 5/11/2021 3 The Log Washer McLanahan Corporation • Designed by Samuel Calvin McLanahan • Patent was granted in 1891 • Original design the paddles attached to 2 wood log shafts. • https://www.mclanahan.com/blog/how-the-log-washer-got-its-name-the-history-of-log-washers Coarse Material Washer Same principle as the log washer What do you do with the dirty water? Series of ponds and weirs Occasionally clean the sediment out of the ponds 5/11/2021 4 Water Clarifier Then we go pour some concrete Any Reason You Wouldn’t Use RCA?Competition Webinar – Questions and Answers The questions submitted during the webinar follow with answers that our speakers have provided. Key resources available include: https://intrans.iastate.edu/app/uploads/2018/09/RCA_practioner_guide_w_cvr.pdf Are recycled concrete aggregates reactive in concrete? New York Tara Cavalline: The susceptibility of RCA concrete to AAR depends on the remaining reactivity of the aggregates contained in the source concrete as well as the reactivity of new aggregates introduced into the mixture. If the source concrete used to produce the RCA was affected by AAR, the reaction may continue when the RCA is used in new concrete. The potential future expansion partially depends on the extent of the alkali-aggregate reaction completed while the original concrete was in service. Producing RCA from agency-sourced concrete containing aggregates that have been previously evaluated for AAR is one strategy to mitigate the risk of ASR. Testing of the RCA in accordance with AASHTO R 80 is another strategy. Conventional approaches to mitigate AAR, such as SCMs and lithium compounds have also been successfully used with RCA. RCA can also be blended with conventional aggregates to reduce the potential for AAR. Is the cement mortar on the aggregate reactive? New York Tara Cavalline: Reactive fine aggregates could be present in the mortar contained in RCA. Testing in accordance with R 80 could be performed to help assess the potential for the mortar fraction of RCA to be reactive. If the coarse aggregate contained in the RCA is reactive, but the fine aggregate contained in the adhered mortar is not reactive, the mortar could also play a role in supporting progression of the AAR, if it allows sufficient alkalis and moisture to contact the reactive coarse aggregate. 1. ASR in the concrete used to make RCA, can manifest in the new concrete. SCMs and low-alkali PC may not control it, because of the cement in the original paste fraction. See papers by M. Shehata et al. Ontario Tara Cavalline: This is good cautionary advice, and use of ASR-susceptible RCA should follow the guidance provided in AASHTO R 80 to evaluate the potential reactivity of the RCA materials and potentially identify approaches (such as inclusion of SCMs) to control the expansion. This paper (and others by the research team led by University of Toronto) are excellent papers for the readers to review: https://intrans.iastate.edu/app/uploads/2018/09/RCA_practioner_guide_w_cvr.pdf Shehata, M.H., Christidis, C., Mikhaiel, W., Rogers, C., Lachemi, M. (2010). “Reactivity of reclaimed concrete aggregate produced from concrete affected by alkali-silica reaction.” Cement and Concrete Research, 40(4), 575-582. Matt Fonte: We replaced 600,000 SY of concrete pavement in eastern Colorado with a severe ASR problem. When the recycled concrete was tested it fail the C1206 Reactive test, and then we ran the 1567 and it showed that the type F Fly Ash was able to mitigate the ASR, much as it would in a natural aggregate. 2. Can RCA be used in roller compacted concrete? Washington AND Are the Recycled Concrete Aggregates RCA with similar aeromechanical properties to be used on Concrete Mixing Wearing Course for Roadways? If not, what kind of further research should the RCA go through to be used on other structural layers like Rolled Compacted Concrete RCC? Pennsylvania It appears that RCA has successfully been used in RCC in some international studies (Fardin and dos Santos 2020, Lopez-Uceda et al. 2018). I am not aware of RCA used in RCC in the United States, but there could be some instances that ACPA is aware of. Fardin, H.E., and dos Santos, A.G. (2020). “Roller Compacted Concrete with Recycled Concrete Aggregate for Paving Bases.” Sustainability, 12, 3154. doi:10.3390/su12083154 Lopez-Uceda, A., Agrela, F., Cabrera, M., Ayuso, J., and Lopez, M. “Mechanical performance of roller compacted concrete with recycled aggregates.” Road Materials and Pavement Design. 19(1), 36-55. https://doi.org/10.1080/14680629.2016.1232659 3. What do you think it will take to get to 100% Replacement of the coarse and fine agg with RCA? Colorado Matt Fonte: Fine aggregates are readily available throughout much of Colorado and the price is relatively low. I don’t see a large demand for recycled fine aggregates in Colorado at this time. 4. How do you get around the calcium/lime leaching out when using it in filter layers? British Columbia Tara Cavalline: Several tactics to address potential issues with calcareous tufa include: • limit the fines content or avoid use of fine RCA • wash the RCA • blend the RCA with virgin aggregate • use high-permittivity filter fabrics • use effective drainage design features Geotextile fabric wrapped around the RCA base and drain trench (per ACPA detail, below) is also a strategy to help prevent clogging. Alternatively, daylighted base designs or stabilized bases (encapsulating the RCA particles in binder) can be used to mitigate precipitate-related drainage problems. Additional guidance is presented in Snyder et al. (2018). ACPA. 2009. Recycling Concrete Pavements. Engineering Bulletin EB043P. American Concrete Pavement Association, Skokie, IL. Snyder, M. B., Cavalline, T. L., Fick, G., Taylor, G., and Gross, J. 2018. Recycling Concrete Pavement Materials: A Practitioner’s Reference Guide. National Concrete Pavement Technology Center, Iowa State University. Ames, IA. How much asphalt millings / chunks can you tolerate in the RCA? British Columbia Tara Cavalline: The allowable level of contaminant material in RCA is dependent on the use of the RCA (Unbound base or fill? Stabilized base? New concrete?). For unbound bases, AASHTO M 319 provides limits on various types of contaminant material. Per AASHOT M 319, RCA should not contain more than 5% bituminous concrete materials by mass if it is to be used in unbound base. In general, for bound uses, the contaminant levels should be minimized to the extent possible, and the material produced (concrete or stabilized base) should be tested during mixture development to ensure adequate mechanical and durability performance. Excessive contaminant material will likely also increase variability in test results. Additional guidance is contained in Snyder et al. (2018). Snyder, M. B., Cavalline, T. L., Fick, G., Taylor, G., and Gross, J. 2018. Recycling Concrete Pavement Materials: A Practitioner’s Reference Guide. National Concrete Pavement Technology Center, Iowa State University. Ames, IA. 5. When used as road base what structural drainage layer coefficients are typically used in design? British Columbia Tara Cavalline: For RCA used as base materials, I have not heard of designers changing the drainage coefficient for RCA from that used for conventional aggregates. 6. Do the references that are cited in this presentation contain any information on CBR values of RCA vs virgin materials for base and subbase applications? Maryland Tara Cavalline: CBR values for RCA in base/subbase applications were not provided in this presentation. However, it appears there is some data compiled in this ASTM publication: A. Arulrajah, J. Piratheepan, M. Ali, and M. Bo, "Geotechnical Properties of Recycled Concrete Aggregate in Pavement Sub-Base Applications," Geotechnical Testing Journal 35, no. 5 (2012): 743-751. https://doi.org/10.1520/GTJ103402 7. A large issue we had was the small fines from the crushing. We used for fill on Capital projects and on trails. Do you have any other suggestions? Iowa AND What could be the ways to enhance use of recycled fine aggregate? France Tara Cavalline: Recommended applications for use of RCA fines include unbound bases, embankment or fill material, and (if free from soil contamination) treated bases. Guidance is provided in Snyder et al. (2018), with additional information published in an upcoming publication, “Use of Construction Byproducts in Concrete Paving Products. Snyder, M. B., Cavalline, T. L., Fick, G., Taylor, G., and Gross, J. 2018. Recycling Concrete Pavement Materials: A Practitioner’s Reference Guide. National Concrete Pavement Technology Center, Iowa State University. Ames, IA. Matt Fonte: The quarries in Colorado have the same problem they have large amount of crusher fines that they have a hard time selling. That is one of the reasons we choose to only take the 3/4” plus material for RCA. Leaving the ¾” minus material as a class 6 road base which is a lot easier to find uses for. In some cases you could use the fine as a structural back fill. As a ¼’ minus material. 8. What is an established way of separating the hydrated cement paste from aggregate during recycling? France Tara Cavalline: From a practical construction standpoint, it is not economical to separate the hydrated cement paste from the aggregate during the RCA production process. Instead, users should develop their production process in a manner that produces RCA with consistent properties and minimal contamination. https://doi.org/10.1520/GTJ103402 Characterization tests can be performed on the RCA in order to understand and account for the differences in properties due to the adhered mortar. From a laboratory testing standpoint, the residual mortar content has been determined by using chemical solutions to dissolve the adhered mortar, using thermal treatment methods, or combinations of both methods. A summary of these methods is presented in the literature review of this report: Hu, J., Cavalline, T., Mamirov, M., and Dey, A., “Effective Characterization of Recycled Concrete Aggregate (RCA) for Concrete Applications. American Concrete Institute. 9. Has RCA for internal curing of concrete (ICC) or modified ICC been used (since there's higher absorption of aggregate)? Virginia Tara Cavalline: There has been some research performed on use of prewetted RCA for internal curing, with reduced autogenous shrinkage being observed as one of the measurable benefits. Publication of interest: Kim, H., and Bentz, D. (2008). “Internal Curing with Crushed Returned Concrete Aggregates for High Performance Concrete.” NRMCA Concrete Technology Forum: Focus on Sustainable Development. Available at: https://www.researchgate.net/publication/242283414_Internal_Curing_with_Crushed _Returned_Concrete_Aggregates_for_High_Performance_Concrete 10. How are absorptions accurately determined to control water in a concrete mix design? Virginia Tara Cavalline: The absorption of RCA can be measured using the same testing methods use for fine and coarse natural aggregates. For RCA fines, which may have a relatively high absorption, the Centrifuge Method by Miller et al. (2014) could be an alternative method to the paper towel method. Miller, A.E., Barrett, T.J., Zander, A.R., and Weiss, W.J. (2014),“Using a Centrifuge to Determine Moisture Properties of Lightweight Fine Aggregate for Use in Internal Curing,” Advances in Civil Engineering Materials, 3(1),142–157. doi:10.1520/ACEM20130111. ISSN 2165-3984 11. Should the RCA mortar be testing for pH and chlorides? Does RCA reduce the pH of concrete when RCA is used? Virginia Tara Cavalline: Typical qualification testing requirements for RCA used in different applications (unbound base/fills, bound base, new concrete) is presented in Snyder et al. (2018). RCA is not typically tested to determine its pH. For use in concrete mixture designs, ACPA (2009) recommends that the chloride content of RCA be limited to 0.06 lb/yd3. https://www.researchgate.net/publication/242283414_Internal_Curing_with_Crushed_Returned_Concrete_Aggregates_for_High_Performance_Concrete https://www.researchgate.net/publication/242283414_Internal_Curing_with_Crushed_Returned_Concrete_Aggregates_for_High_Performance_Concrete Snyder, M. B., Cavalline, T. L., Fick, G., Taylor, G., and Gross, J. 2018. Recycling Concrete Pavement Materials: A Practitioner’s Reference Guide. National Concrete Pavement Technology Center, Iowa State University. Ames, IA. ACPA. 2009. Recycling Concrete Pavements. Engineering Bulletin EB043P. American Concrete Pavement Association, Skokie, IL. 12. I would like to learn of any reference using the recycled concrete aggregate in geopolymer concrete? Virginia Tara Cavalline: Some recent work in this area that I’ve identified include: Koushkbaghi, M., Alipour, P., Tahmouresi, B., Mohseni, E., Saradar, A., and Sarker, P.K. (2019). “Influence of different monomer ratios and recycled concrete aggregate on mechanical properties and durability of geopolymer concretes.” Construction and Building Materials, 205, 519-528. https://doi.org/10.1016/j.conbuildmat.2019.01.174 Nuaklong, P., Sata, V., and Chindaprasirt, P. (2016). “Influence of recycled aggregate on fly ash geopolymer concrete properties.” Journal of Cleaner Production, 112(4), 2300-2307. https://doi.org/10.1016/j.jclepro.2015.10.109 13. Once it's crushed on site is the testing done in site also? California Tara Cavalline: It seems that the location of RCA characterization testing would be project-specific, depending on the contractor’s QC laboratory capabilities and whether an outside testing firm may be hired to assist with QC testing. Field tests would be performed in the same manner as those performed on conventional aggregates. 14. The process uses a lot of water. How much on average? Is environmental impact taken into account? California is facing another draught year. Can you use grey water? California Matt Fonte: If you are talking about the washing process, we use very little water. For the two options I showed, we either use a series of ponds and recycle the water as the sediment settles in the ponds. Or we use a water clarifier system which uses even less water as it only recirculates between the clarifier and the washer. 15. I am concerned about the soundness results. West Virginia Tara Cavalline: Since the paste component of RCA is susceptible to sulfate attack, results in the magnesium and sodium sulfate soundness tests are unreliable for RCA. Therefore, alternative soundness tests can be used, as described in AASHTO M 319. These approaches include AASHTO T 103, which is a freeze-thaw procedure conducted in water with 25 cycles of freezing and thawing and a maximum allowable loss of 20%. Other listed alternates are the NYSDOT Test Method NY 703-08 and https://doi.org/10.1016/j.conbuildmat.2019.01.174 Ontario Ministry of Transportation Test Method LS-614, both of which involve freeze-thaw cycles in a sodium chloride brine solution with a maximum allowable mass loss of 20%. 16. Are the sediments suitable to be used as a liner for landfills? Florida Tara Cavalline: I have not seen publications regarding the suitability of RCA fines to be included as material lining a landfill. It would seem to me that RCA fines could potentially be used in landfill applications if the material meets the specification requirements of other aggregates. One characteristic that may be explored is the potential for high pH runoff, and its implications, if the material is used in a drained application. 17. Can you talk about the suitability of RCA from vertical construction? Florida Tara Cavalline: I will assume that this question is asking about RCA in concrete mixtures, as opposed to RCA used in unbound applications (fill/base) to support vertical construction. Much research has been performed on RCA concrete mixtures, with the aim at understanding the potential for this material to be used in vertical construction. Many studies have indicated that the undesirable changes to concrete mixture performance resulting from use of RCA can be accommodated using readily implementable mixture design and proportioning techniques. However, widespread use of RCA in vertical construction has not become accepted in the United States. Recent changes to the building code ACI 318-19 allow crushed concrete or recycled aggregate. However, the code does not include specifications for design criteria, and instead indicates that any alternative materials just be approved by the licensed design professional and the building official. Therefore, suppliers and producers will be required to perform testing, providing data regarding the anticipated product performance. Some additional information, including testing considerations, is presented in Mohle (2019). Mohle, J.P. (2019). “ACI 318-19 brings new provisions for alternative cements and aggregates.” Concrete Products, September 10, 2019 edition. Available at: http://concreteproducts.com/index.php/2019/09/10/aci-318-19-brings-new-provisions- for-alternative-cements-and-aggregates/ 18. Does the log washer have magnets to remove any metal pieces? Florida Matt Fonte: No, the magnets are on the crushers. The metal is removed during the crushing process usually in large pieces. 19. Do you only use the product with a portable batch plant or have you had success in stationary batch plants? California Matt Fonte: Castle Rock Construction only owns portable plants, but the process would be the same for stationary plants. You can use RCA in any concrete plant. 20. Does it matter what the original mix design was of the RCA and how it's applied to a new concrete mix design? Iowa Tara Cavalline: The quality of the source concrete used to produce the RCA will influence both the mechanical properties and the durability performance of the new concrete produced using that RCA. The performance history of the source material should be assessed prior to use as RCA in new concrete. Often RCA concrete has reduced strength compared to concrete produced with natural aggregates. However, the stronger the source concrete mixture, the smaller the reduction in strength (Snyder et al. 2018). The permeability of the new concrete (and its ability to resist penetration of fluids and aggressive agents) will be dependent on the w/cm ratio used in the new mixture, as well as the permeability of the adhered paste contained on the RCA. The air content of the source concrete must also be considered when aiming to use RCA to produce new, freeze-thaw resistant concrete mixtures. The potential for alkali- aggregate reactivity and D-cracking distress being introduced to the new concrete through use of susceptible RCA must also be considered. Additional guidance is presented in Snyder et al. (2018). Snyder, M. B., Cavalline, T. L., Fick, G., Taylor, G., and Gross, J. 2018. Recycling Concrete Pavement Materials: A Practitioner’s Reference Guide. National Concrete Pavement Technology Center, Iowa State University. Ames, IA. Competition Webinar – Questions and Answers | |
| NCC NC² Spring 2021 Online Meeting—April 15 | 👤 Peter Taylor 👤 David White 👤 Mark Snyder 👤 Jason Weiss 👤 Richard Bradbury 👤 Tara Cavalline 👤 Craig Hughes | NC² Meeting | Spring 2021 |
| 2021-04-15 | 4/20/2021 1 Peter Taylor • Dr. Peter C. Taylor P.E. (IL) FACI is the Director of the National Concrete Pavement Technology Center at Iowa State University. • He spends time helping agencies ask for better concrete and helping contractors deliver it. Geotextile Interlayer for Overlays Peter Taylor, Yifeng Ling 4/20/2021 2 Background • How does the geotextile influence vertical deflections in the system? • Does this tendency change over time? • Does the thickness of the textile matter? • Is the risk of slab migration changed? • Are there any other impacts of reduced friction between layers? • Are the layers effective at providing drainage and does it change over time? • Does the risk of cracking change? • Does the color of the textile affect thermal performance of the slab? 3 Lab work • Variables • Fabric thickness – 5-7 oz. (1 mm) and 13-15 oz. (3-3.5 mm) • Black and white fabric 4 4/20/2021 3 Lab work • Measure temperature rise behind sample exposed to a heat lamp • Investigate thermal mass of the interlayer • Load deflection plot for bare textile • Load deflection test on composite sample 5 Results Exposed face, °F Shadowed face, °F Thick Black 105 112 Thick White 105 98 Thin Black 110 115 6 • Black material does get hotter • Mass is so low, effect on concrete is small 4/20/2021 4 Results Exposed face, °F Shadowed face, °F Thick Black 111 87 Thick White 102 90 Thin Black 105 104 7 • Black material surface does get hotter • Both colors insulate about the same • Increasing thickness = better insulation Results • Using specific heat capacity from published data • For 6” concrete overlay • Start with separator layer at 120°F and concrete at 70°F • Concrete temperature increase • 1” Asphalt – 8.0°F • 3 mm Textile – 0.3°F • Still need to account for base temperature 8 6” Varies 4/20/2021 5 Results • Load deflection plot for bare textile between metal plattens 9 4” metal (top) Textile 4” metal (bot) LVDT Results • Load deflection plot in concrete 10 4” new concrete(top) Textile 4” old concrete(bot) LVDT Concrete Modulus of Elasticity, ksi Black Concrete 3 1,739 White Concrete 3 1,889 Black Concrete 1 3,467 4/20/2021 6 Results • Textile vertical movement <0.05” (~1 mm) • System stiffness is reduced with thicker textile 11 Field Work • … 12 4/20/2021 7 4/20/2021 1 In Situ Cyclic Loading of Concrete Pavement Overlays Supported on Geotextile and Asphalt Interlayers David J. White, Ph.D., P.E., President and CEO, Ingios Geotechnics, Inc Peter Taylor, Ph.D., P.E., Director, National Concrete Pavement Technology National Concrete Consortium, Spring 2021 WEBINAR Existing AC Pavement (Pre-Overlay) PCC Pavement (Post-Overlay) Pre-Overlay Post-Overlay 12in. AC 6 in PCC overlay on 12in. AC D16 Buchanan County, Iowa P.C.C. overlay 2020 4/20/2021 2 Geotextiles have been in use as separation layer for over a decade in the US. Some questions yet remain: How does the geotextile influence vertical deflections in the system? Does this tendency change over time? Does the thickness of the textile matter? Is the risk of slab migration changed? Are there any other impacts of reduced friction between layers? Are the layers effective at providing drainage and does it change over time? Does the risk of cracking change? Does the color of the textile affect thermal performance of the slab? Automated Plate Load Testing (APLT) was used for In situ assessment of the performance of different interlayer sections in Iowa. V18, Poweshiek County, Iowa (Sections built in 2008/2009, Tested in October 2016) 4/20/2021 3 V18, Poweshiek County Test Sections AC Interlayer Fabric InterlayerFabric Interlayer Permanent deformation values were lower in geotextile fabric sections than in AC interlayer sections 4/20/2021 4 Resilient Modulus values were higher in the geotextile fabric sections than in AC interlayer sections Summer 2020 Test Sections 4/20/2021 5 Variables Fabric Thickness (5-7 Oz versus 13-15 Oz): • Standard Black Geotextile - Tencate MPBBC1450 • Thin Black Geotextile - TenCate Mirafi 160N/12.5/360 Color of Geotextile (White vs. Black): • White Geotextile – Reflectex® by Propex • Standard Black Geotextile - Tencate MPBBC1450 Buchanan County, Iowa 7/10/2020 Existing Conditions: 12 in. AC Layer 4/20/2021 6 Existing Conditions: 12 in. AC Layer Picture Courtesy of Dan King, P.E. Iowa Concrete Paving Association 7/10/2020 Existing Conditions: 12 in. AC Layer 7/10/2020 4/20/2021 7 Existing Conditions: 12 in. AC Layer 7/10/2020 White Geotextile – Reflectex® by Propex Standard Black Geotextile - Tencate MPBBC1450 7/10/2020 7/22/2020 Picture Courtesy of Dan King, P.E. Iowa Concrete Paving Association 4/20/2021 8 7/10/2020 7/22/2020 Picture Courtesy of Dan King, P.E. Iowa Concrete Paving Association Thin Black Geotextile – TenCate Mirafi 160N/12.5/360 White Geotextile – Reflectex® by Propex Picture Courtesy of Dan King, P.E. Iowa Concrete Paving Association 4/20/2021 9 CONTROL SECTION Picture Courtesy of Dan King, P.E. Iowa Concrete Paving Association Picture Courtesy of Dan King, P.E. Iowa Concrete Paving Association 4/20/2021 10 12 IN. DIAMETER LOADING PLATE CYCLIC AND STATIC APLT APLT TESTING PLAN • 12 in. diameter loading plate • CYCLIC PLT @ 100 psi cyclic stress for 1,000 cycles • INCREMENTAL LOADING STATIC PLT up to 120 psi (load/reload cycles) • STATIC AND CYCLIC DEFLECTION BASIN • FOLLOW-UP TESTING 1 YEAR AFTER CONSTRUCTION 4/20/2021 11 Permanent deformation values under cyclic loading. 0 0.002 0.004 0.006 0.008 0.01 0 100 200 300 400 500 600 700 800 900 1000 P e rm an e n t D ef or m at io n, d p (i n. ) Cycles Control_1147+40 Control_1154+00 White_1155+50 White_1156+50 Black_1162+00 Black_1166+00 Thin Black_1174+00 Thin Black_1176+00 CONTROL WHITE WHITE STD. BLACK STD. BLACK THIN BLACK THIN BLACK 0 100,000 200,000 300,000 400,000 500,000 600,000 0 100 200 300 400 500 600 700 800 900 1000 R es ili n e t M od u lu s, M r (p si ) Cycles Control_1140+47 Control_1154+00 White_1155+50 White_1156+50 Black_1162+00 Black_1166+00 Thin Black_1174+00 Thin Black_1176+00 Permanent deformation values under cyclic loading. CONTROL WHITE WHITE STD. BLACK STD. BLACK THIN BLACK CONTROL 4/20/2021 12 0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 1140+47 1154+00 1155+50 1156+50 1162+00 1166+00 1174+00 1176+00 PE RM . D EF . @ r at 1, 00 0 CY CL CE S, s = 10 0 PS I ( IN CH ES ) STATION NO. CONTROL WHITE GT STD. BLACK GT THIN BLACK GT Permanent deformation values at end of 1,000 cycles in each section. Composite Mr values in different sections pre- and post-overlay 0 50000 100000 150000 200000 250000 300000 350000 400000 450000 500000 1140+47 1154+00 1155+50 1156+50 1162+00 1166+00 1174+00 1176+00 CO M P. R ES IL IE N T M O D U LU S at s = 10 0 PS I ( PS I) STATION NO. POST-OVERLAY PRE-OVERLAY CONTROL WHITE GT STD. BLACK GT THIN BLACK GTCONTROL WHITE GT STD. BLACK GT THIN BLACK GT 4/20/2021 13 0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 1140+47 1154+00 1155+50 1156+50 1162+00 1166+00 1174+00 1176+00 RE BO U N D D EF O RM A TI O N @ r at s = 10 0 PS I ( IN CH ES ) STATION NO. CONTROL WHITE GT STD. BLACK GT THIN BLACK GT Plate rebound values in different sections under cyclic load of 100 psi at 1,000 cycles 0.000 0.002 0.004 0.006 0.008 0.010 0.012 1140+47 1154+00 1155+50 1156+50 1162+00 1166+00 1174+00 1176+00 PE A K D EF O RM A TI O N @ r at s = 80 P SI (I N CH ES ) STATION NO. Initial Load Reload CONTROL WHITE GT STD. BLACK GT THIN BLACK GT Peak deformation under a static load of 80 psi in each section. 4/20/2021 14 Influence of support conditions? Differences in load-deformation hysteresis? APLT performance testing planned for fall 2021. Analysis underway using pavement deflection basin analysis and interlayer k-value calculations 0.000 0.002 0.004 0.006 0.008 0.010 0.012 0.014 0.016 0 20 40 60 80 100 120 140 0 200 400 600 800 1000 1200 1400 D e fo rm a ti o n , d [i n .] C o n ta c t S tr e ss , s [p s i] Time, Sec Stress [psi] Def. @ r [in.] Def. @ 2r Def. @ 4r Def. @ 6r 0.000 0.002 0.004 0.006 0.008 0.010 0.012 0 3 6 9 12 15 18 21 24 27 30 33 36 39 P e ak D ef o rm at io n , d [i n .] Distance Away from Plate Center [in.] 40 psi (Initial) 80 psi (Initial) 120 psi (Initial) 40 psi (Reload) 80 psi (Reload) THANK YOU! David J. White, Ph.D., P.E., President and CEO, Ingios Geotechnics, Inc Peter Taylor, Ph.D., P.E., Director, National Concrete Pavement Technology National Concrete Consortium, Spring 2021 WEBINAR 1 About the Presenter • Mark Snyder is the President of Pavement Engineering and Research Consultants (PERC), LLC and a Special Consultant to the American Concrete Pavement Association (ACPA). • He holds BS, MS and PhD degrees in Civil Engineering from the University of Illinois (Urbana-Champaign) and is a registered professional engineer in Illinois, Minnesota, Pennsylvania and Hawaii. • Mark has more than 40 years of experience in pavement engineering and research, including 13 years as a professor, 10 years of concrete paving association work, and many more years of engineering consulting. • He is currently about 90 percent retired and is trying for 100. Load Transfer Test Results and Proposed Dowel Specification Changes Presented by: Mark B. Snyder, Ph.D., P.E. Pavement Engineering and Research Consultants, LLC Special Consultant to ACPA National National Concrete Consortium (NCC) Spring 2021 Virtual Meeting April 15, 2021 2 Current AASHTO Dowel Specs M 254 – Standard Specification for Corrosion-Resistant Coated Dowel Bars (last revised 2006, reapproved 2019) “… specification covers the materials, manufacture and installation of coated dowel bars to be used where corrosion-resistant performance is essential … [t]he dowel shall consist of a steel core covered by an organic coating.” (Emphasis added) For “organically coated” (epoxy- or plastic-coated) dowels, 1.25-in diameter, 20-30 mils coating (Type A, low bond strength) or 5-9 mils (Type B, bond breaker required). Dowels qualified as individual products, not as part of a system. T 253 – Standard Method of Test for Coated Dowel Bars (last revised 2002, reapproved 2020) “..methods to test the qualifications of the organic coating of corrosion-resistant dowel bars to withstand the effects of weathering, de-icing chemicals, and the abrading and loading stresses experienced in field joints.” Current AASHTO Dowel Spec Details Originally approved in 1975 Predominant corrosion-resistant dowel was epoxy-coated solid steel Directly applicable to 1.25-inch cylindrical dowels Structural Testing Load-Deflection (Static Load, Single Dowel) Pullout Durability Testing Abrasion Corrosion Chemical Resistance Cathodic Disbonding Coating Hardness Coating Impact Resistance 3 Limitations of Current AASHTO Dowel Specs Not directly applicable to many dowel products being used and developed today Can’t evaluate different dowel materials Different tests needed for different materials, different coatings Can’t evaluate behavior of groups of dowels No ability to evaluate potential structural performance potential (differential deflection) of nonstandard dowel spacing Difficult for manufacturers to innovate. Difficult for agencies to adopt new products. What is needed: A specification and associated suite of structural and corrosion tests that can: Provide manufacturers with targets and evaluation criteria for innovative improvements, and Provide agencies with objective measures of the relative potential performance of competing products. 4 Brief History Effort initiated by NCC around 2014 Much discussion and energy at first Various drafts and concepts presented and discussed Early 2016 version (Burnham and Snyder) gained general support/consensus of NCC agency members, but interest in concept was insufficient to drive to completion. In Mid-2016, ACPA’s Jointing Task Force resolved to pick up where NCC left off “Universal” Dowel Spec subcommittee established to include manufacturers and suppliers of dowel products, ACPA Chapter/State staff, and ACPA National staff (with interested NCC state DOT reps as subcommittee “friends”) Objectives Establish specifications and tests that can be used by agencies for evaluation of all dowel systems Provide indications of performance potential Structural adequacy Durability (Corrosion resistance, etc.) Use existing T 253/M 254 as basis of development 5 Structural Testing of Dowel Systems Current AASHTO T253 Load-Deflection Test Schematic Performance criterion: Limit relative deflection across joints to 10 mils (0.01 inches). 6 ACPA T253 Load-Deflection Test Schematic ACPA T253 Load-Deflection Test Schematic Performance criterion: Limit relative deflection across joints to … ??? 7 ACPA T253 Load-Deflection Test Schematic ` 24” Unsupported 4000 Pounds 10” 12” AASHTO T253 Load-Deflection Test Sensitivity to K (Theoretical) Source: K. Alland, Univ. of Pittsburgh 8 ACPA T253 Load-Deflection Test Sensitivity to K (Theoretical) FE analysis indicates AASHTO standard T253 test with 10-mil relative deflection should produce 20 mils relative deflection in ACPA T253 procedure. Validation testing required. Source: K. Alland, Univ. of Pittsburgh Validation of New Structural Test Protocol Goal: Validate multi-dowel structural model behavior (load-deflection) and acceptance threshold (~20 mils) Testing: 4 replicates AASHTO T253 load-deflection testing 1.25-inch diameter epoxy-coated steel dowels Yields 8 measurements of relative deflection 2 replicates of the proposed modified version of this test Four 1.25-inch diameter epoxy-coated steel dowels per joint Four test locations per specimen (one in each of the four corners of the unsupported slab) Yields 8 measurements of relative deflection Test protocol modification: Hold load for 10 mins at specified peak (4000 lbs or 9000 lbs), measure RD at start and end of hold Increase load to 150% of specified peak Hold load for 10 mins at new peak (6000 lbs or 13,500 lbs), measure RD at start and end of hold Release load; measure RD at release and 1 minute after release. Companion compressive strength/elastic modulus test cylinders 9 Funding and Execution of Validation Testing Request for Testing Proposals solicited by ACPA from 3 labs. Construction Technology Laboratories (Skokie, IL) selected Testing funded by National Concrete Consortium through the CPTech Center at Iowa State University Some staff time donated by ACPA Standard epoxy-coated dowels donated by TyE Bar, LLC Testing performed May 20-21, 2020 CTL Specimen Moulds with Dowels and Lift Anchors 10 Joint Forming Detail Test Stand Setup ACPA T253 AASHTO T253 11 Test Results – AASHTO T253 Load-Deflection (with added load and holds) Concrete Strength (all specimens): 14-day compressive: 5590 psi 28-day compressive: 6360 psi 28-day elastic modulus: 4700 ksi ` 24” Unsupported 4000 Pounds 10” 12” AASHTO T253 Load-Deflection Test Sensitivity to K (Theoretical) Test data suggest K~2.1E6 psi/in ~2.8 12 ACPA T253 Load-Deflection Test Sensitivity to K (Theoretical) 2,100,000 ~7 Predicted deflection ~7 mils Test Results – ACPA T253 Load-Deflection (with added load and holds) Specimen 1 Specimen 2 13 Comparing Test Results – AASHTO T253 vs ACPA T253 Load-Deflection ACPA T253 Specimen 1AASHTO T253 (Average of all tests) New test procedure has higher absolute variability (but comparable relative variability) For tested materials, highest AASHTO standard test result is about 3.75 mils or 37 percent of 10-mil limit For tested materials, highest ACPA standard test result is about 7 mils or 37 percent of 20-mil limit Load-deflection response fairly linear (50% increase in load results in approximately 50 percent increase in relative deflection) Very little load-hold drift observed at standard load; slight drift at increased load Recommendation for Implementation in Specifications Consider 20-mil limit for new test to be comparable to 10-mil limit for old test for standard loading 4000 lbs in AASHTO T253 9000 lbs in ACPA T253 Evaluate using higher load (13500 lbs) for high-volume, heavy load routes Evaluation threshold to be set by specifying agency in context of design reliability Higher thresholds for low-volume roads, parkways, etc.; lower for heavy traffic, long service life, etc. Lower thresholds for soft, unbound foundations; higher thresholds for strong, stabilized foundations, etc. Limit drift for heavy load pavements? 14 Alternate Structural Evaluation Techniques (Agency Option) Dynamic load testing (e.g., Pitt ALF) Analytical evaluation Compute or model shear, bending and bearing stresses Test: • 10M Load Cycles • Simulate 9000 lb wheel load • Simulate 45mph vehicle speed • Costly and time- consuming Used as part of dowel acceptance standard by several DOTs • PennDOT PTM 642 • MnDOT HP Dowel Approval Procedure ACPA Specification Development Agency Staff MnDOT - Maria Masten, Rob Golish PennDOT - Neal Fannin MoDOT - Brett Trautman ACPA National - Jerry Voigt, Eric Ferrebee WCPA – Kevin McMullen Dowel Manufacturers/Distributors O-Dowel - Chris Schenk Artazn - Mike Mather CMC – Bassam “Ben” Sadawi MasterDowel – Brad Zaun PNA – Feng Mu AHT/Simplex – Glenn Eder, Mark Kaler CRT – Jim Olson Owens Corning – Doug Gremel, Bryan Barragan AASHTO T253 and M254 used as basis for development Primary goal: Incorporate new load-deflection test Development approach: Keep general AASHTO spec format and content to extent possible Specification Development Committee 15 New ACPA “Universal” Dowel Specifications M 254 – Standard Specification for Dowel Bars for Concrete Pavement Specification developed to address the requirements for manufacture and installation of all types of dowel bars (coated or not, corrosion- resistant or not, cylindrical or not, metallic or not) intended for use in concrete pavements. Dowels qualified as engineered load transfer systems, not as individual products. T 253 – Standard Method of Test for Dowel Bars for Concrete Pavement Methods to test: Structural behavior or dowel load transfer systems Ability of dowels to withstand the effects of weathering, de-icing chemicals, UV exposure, abrasion and other measures of dowel durability. Suite of applicable durability tests varies with dowel materials and coatings. Dowel Types (determines applicable test suite) Type A - Single metallic material AASHTO M255 or M334, ASTM A276, A312, A955 or A1035 (CS, CM and CL) Grade as specified by purchaser. Type B - Single nonmetallic material ASTM D7957** or as specified by the purchasing agency. Type C – Metallic core with metallic corrosion protection Steel core : AASHTO M 255 or M334, ASTM A513 or A615 Metallic corrosion protection: ASTM A249, A276 or A312 for stainless steel coatings, ASTM A513, ASTM A1035 (CS, CM and CL) for low-carbon chromium coatings, ASTM B69 for rolled zinc coating, or ASTM A1094 for hot-dip galvanizing. Type D – Metallic core with nonmetallic corrosion protection Core material: AASHTO M255 or M334, ASTM A276, A312, A513, A615, or A1035 (CS, CM and CL); grade specified by the purchasing agency. Type D1: mechanically bonded nonmetallic cladding material (ASTM D7957* or as specified by purchaser), e.g., GFRP Type D2: meet requirements of ASTM A1078 one or more thin layers of epoxy, plastic or similar materials of primarily organic composition … epoxy coating systems to meet material requirements of ASTM A775, A934 and/or CSA-Z245.20. 16 Physical Test Requirements Load Deflection Testing (all dowel types) Pullout (measure surface shear instead of total force; all dowel types) UV Exposure (Types B and D only) Abrasion (all dowel types) Corrosion (all dowels with metallic components – Types A, C and D) Primary consideration to lateral surfaces, not ends Chemical Resistance (Type D2 only) Cathodic Disbonding (Type D2 only) Coating Impact Resistance (Type D2 only) Acceptance/Rejection Thresholds for Tests Specifications generally define which tests to perform, how to perform them and how to measure/obtain results Different types of tests apply to different dowel material/coating combinations Acceptance/rejection criteria are often not provided Agencies determine limit values and how they are categorized for service life and/or climate Concept is similar to specs for determining PCC compressive strength and other material properties Guidance is provided (notes to specifiers) to aid agencies in setting/modifying acceptance/rejection thresholds 17 Comparing AASHTO and ACPA M254 Specs – Dowel Types 1.2 The coated dowels shall be one of the two following types: Type A – Coating material develops low bond strength with concrete – no bond breaker required. Type B – Coating material develops bond strength with concrete – bond breaker is required. 1.2 Dowels are categorized according to primary material type (metallic or nonmetallic) and the type of corrosion protection coating used (e.g., none, metallic, or nonmetallic) – regardless of [dowel shape] – using the following type designations: Type A – The dowel comprises a single uncoated metallic material (e.g., carbon steel, low-carbon chromium steel, stainless steel, or other metallic alloys). Type B – The dowel comprises a single uncoated non- metallic material (e.g., FRP). Type C - The dowel has a metallic core and is coated, clad or sleeved with a different metallic material (e.g., stainless steel or zinc alloy cladding/sleeving of a carbon steel core). Type D - The dowel has a metallic core and is coated, clad or sleeved with a non-metallic material (e.g., epoxy-coated, plastic/polyethylene-coated and FRP-clad carbon steel dowels). Comparing AASHTO and ACPA M254 Specs – Dimensions 5.1 Core metal shall be 1.25-in diameter or as specified. 5.2 Nonabraded thickness of coatings: Type A: 25 + 5 mils. Type B: 7 + 2 mils 5.3 Coating thickness determined using ASTM G12 or by stripping coating from bar. 5.4 Supply dowels in lengths and assemblies or baskets as specified. 5.1 Dowel bar dimensions as specified. Dimensions measured before application of coating or cladding materials except for D1 (CRT dowel – measured before cladding and overall diameter after cladding). 5.1.1 Solid cylindrical dowels – specify min length and min diameter. For D1, specify min core diameter and min overall diameter. 5.1.2 Solid elliptical dowels – specify min length and min required lengths of ellipse section axes. 5.1.3 Tube and pipe dowels – specify min length, wall thickness, and overall diameter. 5.1.4 Plate dowel systems – min required and max allowable plate thickness and all other dimensions to accurately define plate shape 5.1.5 Other dowel shapes – agency calls out structural or behavioral equivalency (e.g., EI or deflection results) of solid steel cylindrical dowel (e.g., 1.25-inch diameter round steel equivalent). 5.2 For Type C and D systems - non-abraded minimum thickness of coated systems shall be sufficient to resist corrosion and impact damage when tested in accordance with ACPA T253-20. Determine coating thickness according to ASTM D7091 or by measuring with high-precision calipers after cutting the bar across its section or stripping the coating from the bar. 18 Comparing AASHTO and ACPA M254 Specs – Physical Requirements Load Deflection: - Test 3 specimens; No relative deflection > 10 mils Pullout: - 2-part test with freeze-thaw in salt solution - Max pullout = 3000 lb - No corrosion, tears, or perforation Abrasion: - Wear depth < 70% of original coating thickness Corrosion: - None visible under 5x magnification Chemical Resistance: - No blistering, softening, disbondment, holidays or undercutting at drilled holes Cathodic Disbondment: - No film failure during first hour of test. - No undercutting during rest of test at drilled holes. Coating Hardness: - Exceeds Knoop Hardness Number of 16 Coating Impact Resistance: - No shattering of disbanding of coating outside of impact area. Load Deflection: - Test 1 specimen, 4 locations; Agency specifies limits - Alternative test or analytical procedure Pullout: - Similar except freeze-thaw portion is agency option UV Exposure: - Agency-established limits on flex strength and modulus changes for B and D1 dowels; conditioning step for D2 dowels. Abrasion: - Agency-specified limits – consider corrosion protection and loss of load transfer. Corrosion: - No visible steel corrosion. Limit corrosion-induced expansion. Chemical Resistance: - Similar Cathodic Disbondment: - Similar, with 4mm disbondment radius limit. Coating Hardness: - Deleted Coating Impact Resistance: - Similar. Comparing AASHTO and ACPA T253 Specs – Materials 3.1 The concrete design and constituents shall be specified by the agency. 3.1 The concrete mix design and constituents shall comply with the following: 3.1.1 Type I, Type II or Type I/II cement conforming to ASTM C150/C150M. 3.1.2 Coarse and fine aggregate conforming with ASTM C33, with coarse aggregate meeting Grading 67 and conforming to Class 4S (ASTM C33, Table 4). 3.1.3 Air-entrained concrete proportioned using ACI 211.1 procedures using 307 + 3 kg cement/m3 of concrete (517 + 5 lb/yd3) produce concrete with 90 + 15mm (3½ + ½ in.) slump and 6.0 + 1.0 percent air content. 19 Comparing AASHTO and ACPA T253 Specs – Pullout Test AASHTO requires initial ½-inch pullout after 48 hours, 12 days added curing, 50 cycles of freeze-thaw while half-submerged in deicing chemicals (1 cycle per day), then additional ½-inch pullout. Approximately 54 days ACPA requires only initial test (2-3 days); freeze-thaw and added pullout is agency option. Also specifies minimum concrete mould-dowel cover. Photo courtesy of American Engineering Testing Required for all dowels. Abrading block fits over about 1/3 dowel perimeter Comparing AASHTO and ACPA T253 Specs – Corrosion-Abrasion Type A (Uncoated metal) – Corrosion test only. Type B (Solid FRP) – Abrasion test only. Types C and D (coated and clad metal) – Both abrasion and corrosion tests. Includes UV preconditioning for epoxy or FRP surfaced dowels. Abrading block covers standard area, regardless of dowel size/shape 20 After abrasion, determine loss of coating thickness. Partially submerge abraded dowels in 10% NaCl for 50 cycles of freeze-thaw. Examine for corrosion under 5x magnification. Comparing AASHTO and ACPA T253 Specs – Corrosion-Abrasion After abrasion, determine loss of coating thickness (Types C and D) or change in diameter (Type B only). Partially submerge Type A and abraded Types C and D dowels in 10% NaCl for 50 cycles of freeze-thaw. Examine for corrosion under 5x magnification. Determine percentage of expansion due to corrosion. Comparing AASHTO and ACPA T253 Specs – Chemical Resistance Test (Epoxy-coated only) Three dowel bars tested using ASTM G20 procedures - Immerse 45 days in • Distilled water • 3M CaCl2 • 3M NaOH • Saturated Ca(OH)2 solution … except ASTM G20 has very different requirements! Modified to be consistent with perceived intent of AASHTO T253 - Provide 3 replicate specimens in each reagent, with and without holidays (as req’d by ASTM G20). - Total of 24 specimens 21 Comparing AASHTO and ACPA T253 Specs – Cathodic Disbonding Test (Epoxy-coated dowels only) Two dowel bars tested using a modified version of ASTM G8: • Cathode and anode are both dowels • 7% mass NaCl solution • 2-volt potential • ¼-inch holiday at mid-depth of both cathode and anode • Test for 30 days AASHTO T253, ASTM A775 and ASTM A934 tests are all different. ACPA T253 was modified to be consistent with ASTM A775 Annex. • Use three 10-inch dowel sections (cathode) and thin platinum electrode (anode) • 3% mass NaCl solution • 1.5-volt potential • 1/8-inch holiday • Test for 168 hrs (7 days) • Limit disbondment radius to 4mm Comparing AASHTO and ACPA T253 Specs – Coating Hardness Test (Epoxy-coated dowels only) Coating hardness test procedure in AASHTO T253 has been deleted from ACPA T253. • This test is not a part of either ASTM A775 or A934, and the related ASTM standard (D1474). • It is a method for determining “indentation hardness of organic materials such as dried paint, varnish and lacquer coatings applied to an acceptable plane, rigid surface, for example metal or glass.” • Committee determined this is test is not directly applicable to epoxy-coated pavement dowel systems and unlikely to provide information not provided by other tests in the specification (e.g., the coating impact resistance test. 22 Comparing AASHTO and ACPA T253 Specs – Coating Impact Resistance Test (Type D dowels only) Test three dowels using an impact force of 80 in-lb with a 4-lb “tup” according to ASTM G14. ASTM G14 process includes different tup weights, different drop heights, and is an iterative process – very different from AASHTO T253 description. ACPA T253 references instead ASTM A775 Annex A1.3.9, which is essentially the same as AASHTO T253 except for allowing three tests at different locations on a single dowel. Next Steps ACPA publishing (website) current standards as ACPA Guide Specifications Agency “champions” promote new specifications to AASHTO for adoption Engage NTPEP for use of new specifications and tests for single- source testing of dowel products Consider Supplemental Test Program 23 Mark B. Snyder, Ph.D., P.E. – President and Manager Pavement Engineering and Research Consultants (PERC), LLC Special Consultant to American Concrete Pavement Association mbsnyder2@gmail.com April 14th 2021 jason.weiss@oregonstate.edu © Slide 1 of 44 COLLEGE OF ENGINEERING School of Civil and Construction Engineering Jason Weiss, Edwards Distinguished Professor, Oregon State University Reducing Unwanted Cracking: Shrinkage and Shrinkage Cracking April 14th 2021 jason.weiss@oregonstate.edu © Slide 2 of 44 Things Shrink Photo 214024724 © Ljupco | Dreamstime.com On its own shrinkage is not a big issue However, if the displacement is fixed, there will be stress April 14th 2021 jason.weiss@oregonstate.edu © Slide 3 of 44 Todays Outline minimize paste, SRA, int. curing, expansive agents, fibers April 14th 2021 jason.weiss@oregonstate.edu © Slide 4 of 44 Todays Outline minimize paste, SRA, int. curing, expansive agents, fibers April 14th 2021 jason.weiss@oregonstate.edu © Slide 5 of 44 Photo 215481085 © Olga Sabirjanova | Dreamstime.com Origins of Deformation April 14th 2021 jason.weiss@oregonstate.edu © Slide 6 of 44 Thermal Expansion and Contraction TEMP Temperature Deformations Typical COTE ( /C) Steel ~ 12-17 Aluminum ~ 25 Concrete ~ 11 T TL TEMP TEMP materials (in concrete moisture dependence exists) Longitudinal Strain ( ) -20 0 20 40 60 80 100 Weiss, CE 231, 2001 April 14th 2021 jason.weiss@oregonstate.edu © Slide 7 of 44 Expansion/Contraction Joints Internal vibrationmotion due to the storage of energy properties depend on the thermal properties of a material Robert Brown studied plant pollen under a microscope, pollen jiggled randomly Brownian motion (1828) molecules in some liquids and gases he was studying had a special motion or movement Weiss, CE 231, 2001 April 14th 2021 jason.weiss@oregonstate.edu © Slide 8 of 44 -70 -60 -50 -40 -30 -20 -10 0 Change in Relative Humidity (%) -5000 -4000 -3000 -2000 -1000 0 1000 30 40 50 60 70 80 90 100 Relative Humidity (%) 0% SRA -70 -60 -50 -40 -30 -20 -10 0 Change in Relative Humidity (%) -5000 -4000 -3000 -2000 -1000 0 1000 30 40 50 60 70 80 90 100 Relative Humidity (%) 0% SRA Shrinkage Due to Moisture Loss 31 RHNSH in Moisture (Drying External or Internal) and Chemical Reaction Change in Length (Volume) Moisture Moisture Deformations Non-Linearity comes from different mechanism Weiss 2005 April 14th 2021 jason.weiss@oregonstate.edu © Slide 9 of 44 Origins of Non-Linearity 0 5 10 15 20 25 Weight Loss (%) 60 40 20 0 85% 75% 35% 20% 55% W/C = 0.5 Relative Humidity Typical ASTM Result Water Lost From Big Pores Water From Smaller Pores Menisci Interlayer > 40-60% RH >50% RH < 40% RH After Roper April 14th 2021 jason.weiss@oregonstate.edu © Slide 10 of 44 Capillary Stress factors influencing shrinkage Thomas Young Marquis de Laplace (1749 - 1827) Carl F. Gauss (1777 - 1855) Lord Kelvin (1824 - 1907) RT V p RT V r RH p p W cap W 0 cos2 lnln r pcap cos2 Hydrating Cement Water Capillary Stress Sant et al. 2008 April 14th 2021 jason.weiss@oregonstate.edu © Slide 11 of 44 Irreversibility RewettingDrying Reversible Shrinkage Irreversible Shrinkage April 14th 2021 jason.weiss@oregonstate.edu © Slide 12 of 44 Todays Outline minimize paste, SRA, int. curing, expansive agents, fibers April 14th 2021 jason.weiss@oregonstate.edu © Slide 13 of 44 Types of Shrinkage (Strictly Just Due to Water Loss, Evaporation or Suction) or Moisture Loss (Chemical and Self-Desiccation Shrinkage During Hydration) drated Cement Paste Reacts with Carbon Dioxide Change is Still Plastic April 14th 2021 jason.weiss@oregonstate.edu © Slide 14 of 44 Drying Shrinkage (ACI 116) Shrinkage: Decrease in either length or volume. May be restricted to the effects of moisture content or chemical changes. Drying Shrinkage: Shrinkage that is caused by drying. (Size dependence) ASTM C 157 (23C, 50% RH) Time after Drying (Days) M e a s u re d S h ri n k a g e Measured Shrinkage Three Dimensional Phenomena 0l l Weiss, CE 530, 2002 April 14th 2021 jason.weiss@oregonstate.edu © Slide 15 of 44 Chemical Shrinkage reduction associated with the hydration reactions in a cementitious model shown ~ 6.4% reduction April 14th 2021 jason.weiss@oregonstate.edu © Slide 16 of 44 Autogenous Shrinkage protocols should be standardized to replace tests that miss critical information been compared agreement is observed between different protocols April 14th 2021 jason.weiss@oregonstate.edu © Slide 17 of 44 Measuring Shrinkage Starting Time is Critical Measured Shrinkage Time (Days) Measured Shrinkage Time (Days) 0.30 0.40 0.50 0.60 0.70 Water to Cement Ratio 0 250 500 750 1000 Constant Aggregate Volume (70%) 0.30 0.40 0.50 0.60 0.70 Water to Cement Ratio 0 250 500 Constant Aggregate Volume (65%) Autogenous Shrinkage at 24 Hours Time (Days) A ct u a l S h ri n ka g e Time (Days) A c tu al S h ri n ka g e After Aitcin 1999 measurements Begin at the Time of Demolding (i.e., 24 Hours) Convenient Time for the Technicians to Demold Low W/C Concrete Weiss, CE 530, 2002 April 14th 2021 jason.weiss@oregonstate.edu © Slide 18 of 44 Carbonation Carbon Dioxide forming Calcium Carbonate from CH and CSH But Can Be High if High Concentration of C02 is Present Distribution 0% -0.1% -0.2% S h ri n k a g e S tr ai n ( S h ri n k a g e S tr ai n ( Shrinkage Due to Drying Only S h ri n k a g e S tr ai n ( Relative Humidity (%) S h ri n k a g e S tr a in 100 50 0 Simultaneous Drying and Carbonation Drying and Subsequent Carbonation After Mindess, Young and Darwin April 14th 2021 jason.weiss@oregonstate.edu © Slide 19 of 44 Todays Outline minimize paste, SRA, int. curing, expansive agents, fibers April 14th 2021 jason.weiss@oregonstate.edu © Slide 20 of 44 Toward an Understanding of Boundary Conditions A material can shrink or expand freely (without stress development) Complete Restrained - development) (a portion of the shrinkage or expansion is prevented) April 14th 2021 jason.weiss@oregonstate.edu © Slide 21 of 44 Toward an Understanding of Boundary Conditions A material can shrink or expand freely (without stress development) Complete Restrained - development) (a portion of the shrinkage or expansion is prevented) FHWA PCA PCA Barde et al. 2007 April 14th 2021 jason.weiss@oregonstate.edu © Slide 22 of 44 Creep/Cracking Effect Stress Relaxation 28 , , E t dd E d td SHR Residual Stress Development Weiss et al. 1998, JEM SHRdE d td , Initial Specimen Shrinkage Effect Restraint Effect 0 7 14 21 28 Age of Specimen (Days) 0 4 8 12 Stress Based Stress In Specimen C a lc u la te d T e n s il e S tr e s s (M P a ) 0 7 14 21 28 Age of Specimen (Days) 0 4 8 12 Stress Based C a lc u la te d T e n s il e S tr e s s (M P a ) Final Stress State Stress In Specimen Strength Stress Relaxation April 14th 2021 jason.weiss@oregonstate.edu © Slide 23 of 44 Toward an Understanding of Boundary Conditions A material can shrink or expand freely (without stress development) Complete Restrained - development) (a portion of the shrinkage or expansion is prevented) April 14th 2021 jason.weiss@oregonstate.edu © Slide 24 of 44 Degree of Restraint on the Age of Cracking BBAA ABAB BAB AB EAEA EEAA TF FF 0 D e g re e o f R e s tr a in t (% ) Age of Cracking (Days) Weiss 1997 this relationship is highly non-linear Shrinkage Free Permitted 3 1 1 1 1 RR CC EA EA RHTE April 14th 2021 jason.weiss@oregonstate.edu © Slide 25 of 44 Todays Outline minimize paste, SRA, int. curing, expansive agents, fibers April 14th 2021 jason.weiss@oregonstate.edu © Slide 26 of 44 Transforming RH Pressure into A Stress Profile x Node k=1 Node k=NX-1 Node k=NX Node k=2 Drying Surface Bottom W x Element NX Element 1 Element 2 Compute Humidity Profile Compute Strain Gradient Compute Residual Stress Profile Weiss 1999 April 14th 2021 jason.weiss@oregonstate.edu © Slide 27 of 44 Moisture Gradients MOISTURE GRADIENT INITIAL INCREASING AGE R.H. OF ENVIRONMENT CONCRETE SLAB SHRINKAGE STRAIN GRADIENT DRYING INITIAL SLAB CURLING IN A SLAB Weiss 1999 April 14th 2021 jason.weiss@oregonstate.edu © Slide 28 of 44 The Difference in Shrinkage Across the Specimen in High and Low W/C 40 60 80 100 Relative Humidity (%) 1.0 0.8 0.6 0.4 0.2 0.0 N o rm al iz ed S p ec im en T h ic kn e s s ( X /D ) HAMBIENT HINTERNAL Surface As the Specimen Dries 40 60 80 100 Relative Humidity (%) 1.0 0.8 0.6 0.4 0.2 0.0 N o rm a liz e d S p e c im e n T h ic k n es s ( X /D ) HAMBIENT HINTERNAL Surface Drying Self- Desc Higher W/C Lower W/C Weiss et al. 2006 April 14th 2021 jason.weiss@oregonstate.edu © Slide 29 of 44 Moisture Profiles (NR) SRA (keeps core more saturated, lowers moisture gradients, less curl) V il la ni e t a l. 20 13 April 14th 2021 jason.weiss@oregonstate.edu © Slide 30 of 44 Todays Outline minimize paste, SRA, int. curing, expansive agents, fibers April 14th 2021 jason.weiss@oregonstate.edu © Slide 31 of 44 Simple Tests to Assess Restrained Shrinkage Ring is economic, to which lend it to selection & QC/QA April 14th 2021 jason.weiss@oregonstate.edu © Slide 32 of 44 Original Ring Using an Instrumented Ring Obtaining Residual Stress in From the Restrained Ring Test 0 10 20 30 Time (Days) -200 0 S te el S tr ai n ( ) -100 Measured Strain Using an Instrumented Ring Measure Strain that Develops in Steel Pres Determine Pressure Using an Instrumented Ring Measure Strain that Develops in Steel Determine the Pressure Required to Obtain that Strain Pres Obtain Stress Using an Instrumented Ring Measure Strain that Develops in Steel Determine the Pressure Required to Obtain that Strain Apply Pressure to Concrete and Obtain Tensile Stress 22 22 2 22 2 ICOC ICOC OS ISOS SSteelRrConcrete RR RR R RR Ett IC Hossain and Weiss, CCC, 2004 Shah and Weiss, 2005 0 7 14 21 28 Specimen Age (Days) 0 1 2 3 4 April 14th 2021 jason.weiss@oregonstate.edu © Slide 33 of 44 Drying Direction Drying Leads to a Complex, Changing Stress Field and Bottom has a Constant Stress Shape with a Changing Magnitude Drying From the Top and Bottom Stress Field is Always (1/r2) Drying From the Circumference Complex, Variable Stress Field 0 0.02 0.04 0.06 0.08 Distance from the outer surface (m) -1 0 1 2 3 (m) =0.002 =0.004 =0.008 =0.02 =0.04 =0.08 =0.2 =0.5 =100 Inner Surface of the Conc. Ring Econ / Esteel =0.105 Steel Ring 2nd Law for moisture distribution = 2Dt Measure electrically Moon et al. 2006 April 14th 2021 jason.weiss@oregonstate.edu © Slide 34 of 44 The Dual Ring Test April 14th 2021 jason.weiss@oregonstate.edu © Slide 35 of 44 Minimizing Shrinkage and Cracking Photo 79252774 © Bengul Fidan Kaya | Dreamstime.com April 14th 2021 jason.weiss@oregonstate.edu © Slide 36 of 44 Minimize Paste 0 20 40 60 80 100 Aggregate Volume (%) 0 20 40 60 80 100 Typical Concrete n fAggPasteConcrete fPastePastefAggAggConcrete V VV )1( n 1.2 to 1.7 Stiffer Aggregate More Effective In Restraining Paste Shrinkage Weiss, CE 530, 2006 April 14th 2021 jason.weiss@oregonstate.edu © Slide 37 of 44 Water Curing & Curing Compounds A fundamental difference exists in typical curing Water Ponding, Sprinkling, Burlap: Supply Additional Water Curing Membranes: Reduce Loss of Water to the Environment April 14th 2021 jason.weiss@oregonstate.edu © Slide 38 of 44 Shrinkage Reducing Admixtures (SRA) tension, in doing so they reduce capillary stress and shrinkage reduce to approximately 50% of the original as do shrinkage values 0 4 8 12 16 20 SRA Concentration (%) 0.03 0.04 0.05 0.06 0.07 0.08 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Deionized Water Pore Solution Pure De-Ionized Water r pcap 2 Rajabipour et al. 2006 April 14th 2021 jason.weiss@oregonstate.edu © Slide 39 of 44 Internal Curing Castro et al. 2010 Ba rr et te ta l. 20 14 April 14th 2021 jason.weiss@oregonstate.edu © Slide 40 of 44 Internal Curing Commercial Uses April 14th 2021 jason.weiss@oregonstate.edu © Slide 41 of 44 Expansive Agents effective (offset drying not reduce it useful to evaluate expansive agents restraint Wilson 2018 April 14th 2021 jason.weiss@oregonstate.edu © Slide 42 of 44 Fiber Reinforcement (fibrillated PP, cellulose) by changing viscosity/settlement and bleed cracks and reduce crack width in field as widths are small and transfer 2 AC ST IC SH BC ST w R Shah and Weiss, 2005 April 14th 2021 jason.weiss@oregonstate.edu © Slide 43 of 44 Strength Reduce Rate Stress Developed Reduce Magnitude Time of Drying Te n s il e S tr e s s Strength Stress Developed Time of Drying Te n s ile S tr e s s Reducing Cracking: Rate and Magnitude the magnitude and rate of shrinkage are important is a great example Weiss et al. 1999 April 14th 2021 jason.weiss@oregonstate.edu © Slide 44 of 44 Conclusions minimize paste, SRA, int. curing, expansive agents, fibers 4/20/2021 1 Rick Bradbury Rick is the Director of Materials Testing and Exploration for the Maine Department of Transportation. Early in his career he spent 12 years as a field testing technician and concrete plant inspector. He’s involved regionally and nationally with quality assurance and performance specifications. INTEGRITY • COMPETENCE • SERVICE Image Here Office of Infrastructure R I C K B R A D B U R Y D I R E C T O R O F M A T E R I A L S T E S T I N G & E X P L O R A T I O N M A I N E D E P A R T M E N T O F T R A N S P O R T A T I O N FHWA Perspective on Quality Control FHWA is the source for all images unless otherwise noted. Spring 2021 National Concrete Consortium Webinar 4/20/2021 2 Cost of rework is substantial 9 – 15 percent of project cost Less experienced people Need good systems in place Critical to success of Performance Specifications Why does the agency care about QC? QC is necessary to provide first-time quality Understanding the role of variability Chance v. Assignable Cause Predicting future output Managing a process economically Why does the agency care about QC? Walter A. Shewhart 4/20/2021 3 Courtesy of the New England Transportation Technician Certification Program (NETTCP) Quality Assurance Program Core Elements Courtesy of the New England Transportation Technician Certification Program (NETTCP) Quality Assurance Program Core Elements Materials & Construction VariabilityContractor Quality Control (QC) 4/20/2021 4 Courtesy of the New England Transportation Technician Certification Program (NETTCP) Quality Assurance Program Core Elements Prescriptive/MethodPrescriptive/Method PerformancePerformance Agency dictates how the material or product is formulated and constructed Based on past experience Minimal/uncertain ability to innovate Requires agency to have proper manpower and skill set to provide oversight Agency identifies desired characteristics of the material or product Contractor controls how to provide those characteristics Maximum ability to innovate Reduced oversight burden on the agency Prescriptive vs. Performance Specifications 4/20/2021 5 Acceptance testing that relates to performance Characteristics of a Performance Specification Development and integration of enhanced/robust Quality Control practices and oversight Specification changes—moving from prescriptive to performance Slump Minimum cement content Single aggregate gradation requirements Characteristics of a Performance Specification 4/20/2021 6 Why Move to Performance-type Specifications? Federal-aid Highway Program is moving to a performance-driven approach in all areas Advance/allow/encourage innovation Take advantage of new technologies Agency personnel levels Change in agency skill set Change in contractor skill set Agencies assume the QC responsibility under Method/Prescriptive Specifications Performance specifications transfer QC responsibility to the Contractor Party producing/placing the product controls quality Agencies communicate what they are willing to accept Agency ensures QC takes place Contractor Responsibility for QC 4/20/2021 7 DB shifts control from agency to contractor Risk shifts with control Agency retains responsibility and accountability to the taxpayers Contractor submits proposal including how they will develop and deliver the project Post-award, contractor submits a detailed QC Plan Performance specifications have a similar shift of risk and control QC Plans are analogous Mirror Design-Build (DB) Experience Image Pixabay Quality Control Plans • Should be: • Detailed and Project specific • Current • Reviewed and “Approved” or “Accepted” • Plan approval does not imply product acceptance • Implemented & Enforced • Should not be: • Generic • Paper exercise • Regurgitation of specs 4/20/2021 8 Quality Control Plans “We don’t want a QC Plan. What we want is quality – to give us quality, you need to have a plan.” - Bob Lauzon, ConnDOT Quality measurement is achieved through three acceptance activities: Monitoring the adequacy of contractor QC Performing acceptance inspection to identify visually deficient work Performing acceptance sampling and testing for key quality characteristics, per the specification Agency is obtaining information to confirm that the product meets the specified quality level Agency Acceptance Function 4/20/2021 9 Periodic visual observation of QC inspection, sampling, and testing Review of QC records/documents to ensure properly prepared, maintained, with documented actions Providing feedback to contractor’s personnel Scope of Agency Monitoring Activities Acknowledges the key role of QC in a performance specification Requires an approved QC Plan Testing targets, frequency, and action limits Equipment and construction inspection Requires QC testing and control charts Unit weight Air content/SAM Water content Formation Factor (via Surface Resistivity) Strength AASHTO PP84 Image Pixabay 4/20/2021 10 Cements Widespread use of SCMs Advancements in chemical admixture technology De-icers Agency personnel and experience levels Industry knowledge base “You’re Asking for a Lot of Change” Change has already happened! Agencies alter specifications to remove unnecessary prescriptive requirements (promote innovation) Agencies alter acceptance processes to include QC requirements and monitoring Incorporate new tests and technologies that facilitate real-time QC Contractors “up their QC game” (as needed) FHWA provides agency and industry guidance and funding to facilitate implementation Culture Change Moving Forward 4/20/2021 11 PEM Pooled Fund Participants 19 States + FHWA & Industry (September 2020) PEM Implementation Incentive Pilot Project Contact info Michael.Praul@dot.gov 207-512-4917 4/20/2021 1 About the Presenter • Craig Hughes is Vice President of Field Operations for Cedar Valley Corporation, LLC (CVC), one of the Midwest’s premier highway construction companies, based in Waterloo, IA. • CVC has received 38 national paving awards in the past 16 years. • Craig has served as the Iowa Concrete Paving Association Chairperson, as well as Chair of the AGC of Iowa Specification Committee, and Chair of ACPA’s Maintenance of Traffic Committee. • He has years of experience in environmental testing, remediation, project management, and safety. • Craig served on active duty in the Marine Corps from 1979 – 1990. Quality Control for Paving: A Contractor’s Perspective Presenter: Craig Hughes, Cedar Valley Corp April 15, 2021 4/20/2021 2 Quality comes at a price . . . . . • The cost should be considered in correlation with the degree of quality required for a given project! • Are we building a pavement at Offut A.F.B. or a sub-division street? Quality control is a daily effort! • At the batch plant • At the paver 4/20/2021 3 You have to build a culture that believes quality is important: • Senior staff • Individuals that are setting up equipment, stockpiling materials, batching, testing, placing, finishing, curing, sawing and sealing the concrete Answer the “WHY” questions . . . . • The questions confirm interest and are a sign of progress • Does that mean that “Quality” has arrived? 4/20/2021 4 The Quality Journey • Where does it start? • How long will it take to get there? • Who comes along on the trip? | |
| NCC NC² Spring 2021 Online Meeting—April 14 | 👤 Larry Sutter 👤 Jon Belkowitz 👤 Jamie Farny 👤 Steve Karamihas 👤 Jerod Gross 👤 Tyler Ley | NC² Meeting | Spring 2021 |
| 2021-04-14 | 4/19/2021 1 Harvested Fly Ash Larry Sutter Ph.D., P.E., F.ASTM, F.ACI Materials Science & Engineering Michigan Technological University Background • We expect one key property from concrete: Longevity • Service demands have increased • Use of aggressive deicing chemicals • We have increased our expectations for reduced environmental impact and lower initial and lifecycle costs • SCMs assist us in meeting these goals • Coal Fly Ash is our go-to SCM 4/19/2021 2 Effects of SCMs on Properly Cured Hardened Concrete Reduced No/Little Effect Fly ash Slag Silica fume Natural PozzolanIncrease Varies Strength Gain Abrasion Resistance Freeze-Thaw and Deicer-Scaling Resistance Drying Shrinkage and Creep Permeability Alkali-Silica Reactivity Chemical Resistance Carbonation Concrete Color Effects of SCMs on Properly Cured Hardened Concrete Reduced No/Little Effect Fly ash Slag Silica fume Natural PozzolanIncrease Varies Strength Gain Abrasion Resistance Freeze-Thaw and Deicer-Scaling Resistance Drying Shrinkage and Creep Permeability Alkali-Silica Reactivity Chemical Resistance Carbonation Concrete Color 4/19/2021 3 So what’s the problem? The Problem • Fly ash supplies are challenged by coal-fired power plant closures and conversions to natural gas • Fly ash spot shortages have been reported in many U.S. markets • Concerns center on the fact that no other material is available with the reserves that fly ash historically has provided 4/19/2021 4 Coal-fired Power Plants are Being Retired Navajo Generating Station • 2250 megawatt net coal- fired powerplant • Largest coal fired electrical generating station west of the Mississippi • Produces approximately 500,000 tons a year of Class F fly ash • Closed 2020 4/19/2021 5 Coal-fired Power Plants are Being Retired Source: U.S. Energy Information Administration, 2021 2035 4/19/2021 6 Ash Production is Dropping So What’s Up With Fly Ash? • Domestic fly ash production (new production) will continue decreasing over the next 20 years and beyond • Domestic use of coal for electrical power generation is predicted to continue decreasing • Fewer plants, running at a higher percentage of capacity • Suppliers believe that although total reserves will decrease, the volume of quality ash as a percentage of total production will increase due to dry handling – no more ponding • Harvested ash from landfills/ponds will become a significant fraction of the total reserves 4/19/2021 7 So What’s Up With Fly Ash? • Domestic fly ash production (new production) will continue decreasing over the next 20 years and beyond • Domestic use of coal for electrical power generation is predicted to continue decreasing • Fewer plants, running at a higher percentage of capacity • Suppliers believe that although total reserves will decrease, the volume of quality ash as a percentage of total production will increase due to dry handling – no more ponding • Harvested ash from landfills/ponds will become a significant fraction of the total reserves ~40% capacity factor Harvested Ash • With diminishing production, ash marketers are turning to land fills & ash ponds to recover fly ash • Most harvested sources are Class F ash • Limited research to date on performance of harvested ash • All harvested sources will require processing • Drying • Sizing • Blending • Could lead to more uniformity - or less - depending upon source and degree of processing 4/19/2021 8 Coal Fly Ash • Benefits • Improved workability • Decreased heat of hydration • Reduced cost • Potential increased sulfate resistance and alkali-silica reaction (ASR) mitigation • Increased late strength, and decreased shrinkage and permeability • Concerns • Air-entraining admixture adsorption by residual carbon in the fly ash • Slow initial strength gain (Class F) • Fly ash variability • How reactive is it? Harvested Coal Fly Ash Benefits Improved workability Decreased heat of hydration ? Reduced cost Potential increased sulfate resistance and alkali-silica reaction (ASR) mitigation Increased late strength, and decreased shrinkage and permeability Concerns Air-entraining admixture adsorption by residual carbon in the fly ash Slow initial strength gain (Class F) ? Fly ash variability How reactive is it? 4/19/2021 9 Harvested Ash • Significant volumes of high- quality fly ash have been disposed • Approximately 2000 million short tons produced 1974 - 2013 • Approximately 650 million short tons used 1974 – 2013 • ~33% utilization – 1350 million short tons disposed • Not all is recoverable, but a large fraction is Production and Use of Coal Combustion Products in the U.S. ARTBA 2015 17.7 M short tons produced 29.3 M short tons produced Harvested Ash – Production & Beneficiation • Harvesting operations vary depending on the source characteristics • Standards are being developed to guide harvesting operations • ASTM E3183 Standard Guide for Harvesting Coal Combustion Products Stored in Active and Inactive Storage Areas for Beneficial Use • Provides a framework for characterization of the site, planning and scoping of a harvesting project, the site design and approval process (as applicable), and the implementation of harvesting • Does not address processing the material to meet ASTM C618 or AASHTO M 295 4/19/2021 10 Harvested Ash – Production & Beneficiation • With very few exceptions, harvested ash will be processed for use in concrete • Drying • Needed to meet moisture limits • Screening or air classification, or both • Primarily to address comingled bottom ash • Grinding (last resort) • Bottom ash, cemented particles • Post-treatment • Carbon removal or mitigation Harvested Ash – Production & Beneficiation • More on carbon removal • Many ashes were landfilled originally due to excessive carbon content • Beneficiation Methods • Triboelectrostatic separation • Carbon Burnout • Passivation 4/19/2021 11 Harvested Ash – Production & Beneficiation • More on carbon removal • Many ashes were landfilled originally due to excessive carbon content • Triboelectrostatic separation Mirkowska, M., Kratzer, M., Teichert, C. et al. Principal Factors of Contact Charging of Minerals for a Successful Triboelectrostatic Separation Process – a Review. Berg Huettenmaenn Monatsh161, 359–382 (2016). https://doi.org/10.1007/s00501-016-0515-1 Harvested Ash – Production & Beneficiation • More on carbon removal • Many ashes were landfilled originally due to excessive carbon content • Triboelectrostatic separation Source: http://www.indmin.com/events/download.ashx/document/speaker/8915/a0ID000000ZwxAGMAZ/Presentation 4/19/2021 12 Harvested Ash – Production & Beneficiation • More on carbon removal • Many ashes were landfilled originally due to excessive carbon content • Carbon Burnout • Reburn with coal feed • Fluidized bed combustion • STAR™ Staged Turbulent Air Flow (SEFA) Harvested Ash – Production & Beneficiation • More on carbon removal • Many ashes were landfilled originally due to excessive carbon content • Passivation AEA Molecule 4/19/2021 13 Harvested Ash – Production & Beneficiation • More on carbon removal • Many ashes were landfilled originally due to excessive carbon content • Passivation Harvested Ash – Production & Beneficiation • More on carbon removal • Many ashes were landfilled originally due to excessive carbon content • Passivation Passivation treatments render the surface of carbon non-adsorptive 4/19/2021 14 Harvested Ash – Production & Beneficiation • In the near term, harvested ash will be sourced from mono-fills where only fly ash was deposited • Long term, fly ash co-mingled with other materials will be harvested, requiring more extensive processing • Mixtures of fly ash and bottom ash will be produced • Testing – primarily reactivity testing – will become more important to ensure uniformity A Little More on Bottom Ash • A common “concern” expressed – inclusion of bottom ash • Bottom ash is chemically similar to fly ash from the same combustion process, and performs in a similar manner • Grinding improves bottom ash performance and ground bottom ash has been shown to perform as well or in some cases better than fly ash from the same combustion process • Coarse bottom ash can be separated by sieving; fine bottom ash cannot be separated from fly ash and will be a component of some harvested materials 4/19/2021 15 Bottom Ash – Example Data Unpublished data: I. Diaz Bottom Ash – Example Data Unpublished data: I. Diaz 4/19/2021 16 Bottom Ash – Example Data Unpublished data: I. Diaz Bottom Ash – ASTM C1567 0.0% 0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% Av er ag e Ex pa ns io n (% ) Cement Replacement (%) GBA-A-F1 GBA-A-F10 GBA-A-F20 GBA-A-F30 FA-A Unpublished data: I. Diaz 4/19/2021 17 Harvested Ash 0.0% 0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% Av er ag e Ex pa ns io n (% ) Cement Replacement (%) GBA-B-F1 GBA-B-F10 GBA-B-F20 GBA-B-F30 FA-B Unpublished data: I. Diaz Harvested Ash 0.20 0.20 0.11 0.09 0.17 0.15 0.20 0.16 0.20 0.16 0.18 0.17 0.00 0.05 0.10 0.15 0.20 0.25 7 Days 28 Days Ca (O H )₂ c on te nt (g /g o f c m ) Cement Control GBA-A-F1 GBA-A-F10 GBA-A-F20 GBA-A-F30 FA-A Unpublished data: I. Diaz 4/19/2021 18 Harvested Ash 0.20 0.20 0.11 0.09 0.13 0.10 0.13 0.11 0.14 0.11 0.15 0.13 0.00 0.05 0.10 0.15 0.20 0.25 7 Days 28 Days Ca (O H )₂ co nt en t ( g/ g of c m ) Cement Control GBA-B-F1 GBA-B-F10 GBA-B-F20 GBA-B-F30 FA-B Unpublished data: I. Diaz Harvested Ash – Testing • Testing for all coal combustion products needs to be improved – harvested ash is only instigating the change • Reactivity • R3 test, modified SAI • Particle Size Distribution • Adsorption Properties • Foam Index, Iodine Number, SorbSensor™ • Uniformity • NCHRP 10-104 addressing many of these issues 4/19/2021 19 Harvested Ash • Concerns • Current federal and state regulations require near-term closure of disposal ponds, leaving insufficient time to recover and use all available ash • Power producers have little to no incentive to use ash beneficially, closure (cap-in-place) is the lowest cost option. • Benefits of landfilled ash • Well over a billion tons of ash in disposal • Proper processing could provide a more uniform product • Significant reserves could help limit cost increases although processing will add costs A Word on ”Off Spec” Ash • So called “off-spec” ash is being considered for use • Note: Existing ash specifications do not address performance (i.e., meeting the specification does not guarantee performance) • If performance of a material can be demonstrated – use it • Common off-spec issues • LOI • Fineness • Materials that are not coal fly ash are not off-spec; they are simply not fly ash – but they may work • Verify reserves – Verify Uniformity 4/19/2021 20 Summary • Harvested ash is here to stay • It will perform comparable to fly ash • It will likely be more expensive due to processing costs • It could be more uniform if processed properly • Specifications need to evolve to ensure this happens • Bottom ash will be comingled with fly ash – it cannot be avoided • It is necessary to test and ensure performance • With luck, we will have ample reserves for the future Questions? llsutter@mtu.edu 4/19/2021 1 About the Presenter Jamie Farny is the Director, Building Marketing for Portland Cement Association. He promotes the use of cement- based materials for buildings and other applications by focusing on sustainability, resilience, energy efficiency, durability, and other key benefits. He assisted with development of PCA’s new campaign to raise awareness of portland-limestone cements (PLCs) for improved sustainability of concrete construction. As a voting member of numerous committees of ACI, ASTM, and The Masonry Society, he works to develop technical guides, codes, and standards related to materials, design, and construction using cement, concrete, and masonry. He holds a B.S. degree in Civil Engineering from the Illinois Institute of Technology. NCC Spring 2021 Webinars PLCs for Paving Applications 4/19/2021 2 A decade of experience for sustainable concrete pavements PLC and Paving American Jobs Plan Modernize highways, roads, and bridges Transportation needs continue to grow Jobs Plan prioritizes resilient infrastructure and recognizes sustainable building materials (such as PLC) Jobs Plan increase for research investments & tax incentives for emerging technologies aligns with industry’s efforts to drive down its carbon intensity Administration has tied infrastructure program to investing in industry & solutions that: Help US/economy recover from the pandemic Look for ways to build more sustainably New $$? Sustainable construction: PLC concrete 4/19/2021 3 A focus on cement and concrete CO2 Footprint of Construction CO2 problem? CO2 opportunity! Whether you are hearing about this from your customers or not, you will soon PLC is proven technology PLC can help position concrete pavements as more sustainable What is PLC? A greener cement option A blended cement with additional limestone content, optimized for performance The easiest way to reduce your carbon footprint by about 10% Suitable for buildings, bridges, pavements, geotechnical applications Readily available throughout the U.S. and Canada 4/19/2021 4 Long Track Record Blended limestone cements History of good performance, even at higher limestone contents than the U.S. Europeans introduced in the late 1960s Canada has used them since the late 2000s U.S. standards in place since 2012 (even earlier as C1157 performance cements) Market share for blended cements grows as users gain comfort working with them U.S. Standards Cementitious Materials and Concrete Standards ASTM/AASHTO C150/M 85 portland cement – up to 5% limestone, Type I or I/II most common C595/M 240 blended cement – 5% to 15% limestone, Types IL and IT. Also pozzolan and slag blended cements, Type IP and IS C1157 hydraulic cement – can contain limestone in varying amounts. Types GU, HE, MS, HS, MH, LH C94/M 157 ready-mixed concrete – equal recognition of C150, C595, and C1157 and equal handling of SCMs 4/19/2021 5 Mix Designs with PLC Proportioning, batching, and mixing PLC replaces ordinary portland cement at 1:1 ratio PLC allows for the same dosages of fly ash or other pozzolans, slag cement As with any new material, some testing is warranted to confirm effect fresh and hardened properties Air content, slump, bleed potential, setting time, compressive strength Some producers report no adjustments are needed, others tweak proportions or adjust admixture dosages Mix Designs with PLC Typical effects on fresh and hardened properties Workability Increase or decrease No significant effect on admixtures Bleeding Decreases with increasing limestone fineness Generally of no concern Setting time (initial, final) Can be slight decrease w/increasing limestone fineness Not a concern even up to 15% limestone Heat of hydration Slight increase at early ages (up to 48 hours) But less significant at later ages Compressive strength Can increase slightly Both early-age and long-term strengths Scaling and freeze-thaw resistance Use same techniques as with OPC concrete mixes: Proper air-void systems, curing, higher strengths Sulfate resistance Use same techniques as with OPC concrete mixes: Low w/c (or w/cm) and MS or HS designations 4/19/2021 6 Working with PLC Mixes Normal operations for: Placing Finishing Curing As fineness increases, may see: Slightly less bleed water Slightly shorter setting times Slightly higher water demand Virtually the same handling and performance as OPC Performance of PLC Concrete A look at hardened properties Strength OPC to PLC comparisons With and without SCMs Durability Scaling Freeze-thaw resistance Chloride permeability ASR resistance Sulfate resistance Field trial results 4/19/2021 7 Performance of PLC Concrete Early age strength development with and without SCMs Thomas and Hooton 2010 Performance of PLC Concrete Later age strength development with and without SCMs Thomas and Hooton 2010 4/19/2021 8 Performance of PLC Concrete “Permeability” T277/C1202 Thomas and Hooton 2010 0 1000 2000 3000 No SCM No SCM 35% Slag 20% Fly Ash No SCM No SCM 35% Slag 20% Fly Ash C ha rg e P as se d (C ou lo m bs ) PC PLC 28 days 56 days W/CM = 0.45 W/CM = 0.45 W/CM = 0.40 W/CM = 0.40 Performance of PLC Concrete Chloride profiles for cores immersed in NaCl solution 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0 5 10 15 Depth (mm) PC - 0% SCM PLC - 0% SCM PC - 25% SCM PLC - 25% SCM PC - 50% SCM PLC - 50% SCM Ch lo rid e (% b y m as s o f c on cr et e) Blair and Delagrave 2012 4/19/2021 9 Performance of PLC Concrete Scaling resistance (ASTM C672) 0 200 400 600 No SCM (0.40) No SCM (0.45) 35% Slag (0.45) 20% Fly Ash (0.45) M as s L os s (g /m 2) Supplementary Cement Materials (w/cm) PC PLC - 12% Thomas et al. 2010 Performance of PLC Concrete Freeze-Thaw Resistance (ASTM C666) Thomas et al. 2010 0 20 40 60 80 100 No SCM (0.40) No SCM (0.45) 35% Slag (0.45) 20% Fly Ash (0.45) D ur ab ili ty F ac to r Supplementary Cementing Materials (w/cm) PC PLC - 12% 4/19/2021 10 Performance of PLC Concrete Field Trials: Pavement slab after one winter PLC + 50% SCM PC + 50% SCM PLC + 25% SCM PC + 25% SCM Performance of PLC Concrete ASR resistance 0 0.1 0.2 0.3 0.4 AMBT CPT ACPT E xp an si on ( % ) Test (age when expansion reported) PC PLC (14 days) (1 Year) (3 months) Thomas et al. 2010 4/19/2021 11 PLC for Special Properties Cement modifiers Sulfate resistance – MS, HS Sulfate-containing soils Sulfate-containing groundwaters Heat of hydration – LH, MH Not generally required Cement type OPC C150 (M 85) PLC C595 (M 240) General use I IL moderate sulfate resistance II, II(MS) IL(MS) moderate heat of hydration II(MH) IL(MH) high sulfate resistance V IL(HS) low heat of hydration IV IL(LH) PLC and Sulfate Resistance Same approach as for other blended cements Use additional SCMs and low w/cm Use moderate- or high-sulfate resistant types: Type IL(MS) Type IL(HS) Type IT(MS) Type IT(HS) Performance confirmed by numerous research studies and decades of field exposures on real-world installations Fly Ash Mixes Standard C1012 23C 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 0 6 12 18 24 30 36 42 48 54 60 66 72 78 Exposure, weeks E x p an si o n , % GU GUL GU + 15% FA GUL + 15% FA GU + 20% FA GUL + 20% FA GU + 25% FA GUL + 25% FA GU + 35% FA GUL + 35% FA 4/19/2021 12 PLC and Heat of Hydration Temperature control for pavements Warm weather Not necessary Mass placements uncommon for pavements (less than 3 ft (1 m) thick) Cold weather Not appropriate Similar to OPC, may need set accelerators or blankets to maintain fresh concrete temperature as placed Procuring PLC Concrete Basics of specifying and ordering A simple revision to specifications: 1:1 replacement of OPC with PLC Same suppliers for your ready mix Same delivery and placing equipment 4/19/2021 13 Specifying PLC Concrete Parallel standards for Type IL ASTM and AASHTO specifications Adoption varies by state ASTM C595 Type IL cement instead of ASTM C150 Type I portland cement Or AASHTO M 240 Type IL cement instead of M 85 Type I portland cement greenercement.com A new resource Calculator for CO2 savings Benefits of PLC Spec language Case studies FAQs Contact an expert Informative videos Mobile friendly 4/19/2021 14 Greener Roads for Right Now! “Excellent durability and improved sustainability” Proven technology Easy to implement Sustainable, resilient pavements These states were some early adopters of PLC concrete pavements – more than a decade ago: Colorado Utah Oklahoma One Colorado Example US HWY 287 Near Lamar Built in 2008 – more than a decade of service Carries heavy trucking & commerce, US - Mexico Summertime construction – hot and dry (100°F) 7 miles paving and shoulder widening PLC (10%L), 20% Class F fly ash 695 psi average 28-day flexural strength Contractor received quality incentive from CDOT 4/19/2021 15 ACPA Activities Portland-Limestone Cements for Pavement Applications ACPA Position Paper May 2020 PCA worked with ACPA to address PLCs for paving “ACPA supports and encourages PLCs for economic and environmental benefits” FHWA encourages DOT’s use of PLCs for more sustainable concrete pavements Point users toward greenercement.com ACPA reports lots of interest in this greenercement.com PLC partners Working with many industry groups to raise awareness and educate about PLC In addition, PCA is creating a roadmap to carbon neutrality by 2050: 5C’s: clinker, cement, concrete, construction, and carbonation PLC is a key component of the roadmap, and as already shown, it’s a market-ready, proven, and effective way to reduce your CO2 by about 10% Asking for PLC is a change you can make today 4/19/2021 16 NCC Spring 2021 Webinars PLC for Paving Applications 4/20/2021 1 About the Presenter • Steve Karamihas is a senior research associate at the University of Michigan Transportation Research Institute (UMTRI). • Steve is a co-author of the Little Book of Profiling. • Steve has conducted research related to vehicle dynamics, road profile measurement, and road profile interpretation for 30 years. • Steve has a Ph.D. in mechanical engineering from the University of Michigan. • Steve is somewhat older than the photo to the right might imply. 1 About the Presenter • Jerod Gross is a Senior Project Manager at Snyder and Associates, Inc., • Jerod has provided concrete pavement design, analysis and technical training for the CP Tech Center. • He has completed research and guidance documents for cement stabilized subgrade soils, concrete trails, concrete overlays and subbase/subgrade foundation performance. • He has a Bachelor of Science degree in Civil Engineering from Iowa State University and is a LEED Accredited Professional. • Jerod now has less hair than what is shown. 2 4/20/2021 2 Maintaining Smoothness Jerod Gross, CP Tech Center and Steve Karamihas, University of Michigan Maintaining Smoothness Discussion Items • Background • Literature Search • State of Practice • IRI Data 4 4/20/2021 3 Maintaining Smoothness: Background Topic Areas • Profile Measurement • International Roughness Index • Measurement Issues – Texture – Curl and Warp • Areas of Localized Roughness (ALR) 5 Profile Measurement 6 0 200 400 600 800 1000 Distance (ft) -.4 -.2 0 .2 .4 Left Elevation (in) sprung mass: ms unsprung mass: mu B ks cs kt C = cs/ms = 6.0 sec-1 K1 = kt/ms = 653 sec-2 K2 = ks/ms = 63.3 sec-2 m = mu/ms = 0.15 B = 250 mm IRI 0 200 400 600 800 1000 Distance (ft) 0 50 100 150 200 Continuous Roughness Report (in/mi) Smoothness QA/QC: “Measuring and Specifying Pavement Smoothness.” Tech Brief FHWA-HIF-16-032 (2016) 12 p. Real-Time Smoothness: https://cptechcenter.org/real-time-smoothness/ 4/20/2021 4 International Roughness Index (IRI) 7 Basics: Sayers, M.W. and Karamihas, S.M. The Little Book of Profiling. University of Michigan Transportation Research Institute (1998) 100 p. Algorithm: Sayers, M.W., “On the Calculation of International Roughness Index from Longitudinal Road Profile.” Transportation Research Record 1501 (1995) pp. 1-12. Generality: Karamihas, S.M., Gilbert, M.E., Barnes, M.A., and Perera, R.W., “Measuring, Characterizing, and Reporting Pavement Roughness of Low-Speed and Urban Roads.” National Cooperative Highway Research Program Report 914 (2019) 84 p. (See pages 59-61.) Inertial Profiler Measurement Principle 8 Schematic Resembles: Huft, D. L., “South Dakota Profilometer.” Transportation Research Record 1000 (1984) p. 1-8. Basics: Sayers, M.W. and Karamihas, S.M. The Little Book of Profiling. University of Michigan Transportation Research Institute (1998) 100 p. Pertinent Reference List: Karamihas, S.M., Improvement of Inertial Profiler Measurements of Urban and Low-Speed Roadways. Ph.D. Dissertation, University of Michigan (2021) 214 p. Reference point h(x) = rzref (x)- rzroad (x) rzref (x) rzroad (x) rzroad (x) = rzref (x)- rzref (x)- rzroad (x)( ) 4/20/2021 5 Measurement Issues: Texture 9 Start Here, Follow the Reference Chain: Perera, R.W. and Karamihas, S.M., “Study for Establishing Regional Certification Centers for Inertial Profilers.” Federal Highway Administration (2014). Measurement Issues: Curl and Warp 10 LTPP Section 040213 Arizona SPS-2 section Jointed plain PCC 15-ft joint spacing lower flexural strength (550 ksi) lower slab thickness (8 inches) dense graded aggregate base PDPJE – partial depth patching at joints and elsewhere Source: Karamihas, S.M., Punnackal, T., Dufalla, N, and Senn, K., “Advancing Profile-Based Curl- and Warp Analysis Using LTPP Profile Data.” Federal Highway Administration Report FHWA- HRT-20-066 (2020) 485 p. 4/20/2021 6 Measurement Issues: Curl and Warp 11 LTPP Section 040213 14.3 years after construction Left IRI: 114 in/mi Right IRI: 145 in/mi Measurement Issues: Curl and Warp 12 Cyclic Roughness Data Source: Chang, G.K., et al. Impact of Temperature Curling and Moisture Warping on Jointed Concrete Pavement Performance. Volume I. Data Collection. Contract DTFH61-02-C-00077, FHWA, Washington, DC. (2007). Pertinent Reference List: See FHWA-HRT-20-066 Appendix A. 4/20/2021 7 ALR: Roughness Profile 13 Basics: Sayers, M. W. “Profiles of Roughness.” Transportation Research Record 1260. (1990) pp. 106–111. ALR on Jointed PCC: See FHWA-HRT-20-066 Appendix J. Literature Search NCHRP 1-31, Smoothness Specifications for Pavements,1997 • Smoother pavements last longer • Data showed initial pavement smoothness has a significant effect on future smoothness 14 The Transtec Group Smoothness Modeling Sensitivity Analysis 4/20/2021 8 Literature Search Longevity of Diamond- Ground Concrete Pavements, Rao et al., 1999 • 60 pavement sections in 18 states + 133 sections from earlier study along with LTPP • LTPP allowed for comparison of diamond ground pavements with other CPR alternatives • Evaluated performance of diamond-grinding and faulting as well as longevity of texture 15 Survival Curves for Diamond-Ground Concrete Pavements Literature Search Longevity of Diamond- Ground Concrete Pavements, Rao et al., 1999 • Mechanical Empirical performance model • Support structure plays a role 16 Effect of Precipitation on Faulting for Non-Doweled Pavements after Diamond Grinding 4/20/2021 9 Literature Search Concrete Repair Best Practices: A series of case studies, Darter, 2017 (MODOT – Const. Materials Division) Includes CPR best practices (cross-stitching, DBR, Diamond Grinding, Full and Partial Depth Repairs, Slab stabilization) Best Practices for Diamond Grinding focuses on Utah DOT specifications, case histories and data • Diamond grinding in Utah shows a service life ranging from 10 to 20 years for undoweled JPCP. 17 18 State of Practice Concrete Pavement Smoothness Specs (2021) 2016 data: Merritt et al., 2015. 2019 data: The Transtec Group, 2020 CP Tech webinar 4/20/2021 10 19 Pending change to IRI State of Practice Concrete Pavement Smoothness Specs (2021) IRI 31 PrI 13 NA 6 IRI = International Roughness Index Prl = ProfiIe Index State of Practice - The Move to IRI 20 Research related to assist in the conversion from Profile Index to IRI specification / development of Smoothness Specification • Pavement Smoothness Index Relationships, Smith, et al., 2001 • Evaluation of INDOT Construction Smoothness Specifications, Pellinen and Chou, 2003 • Implementation of an International Roughness Index for MNDOT Pavement Construction and Rehabilitation, Wilde, 2007 • ACPA/IGGA Guide-Pavement Smoothness Requirements, 2013 Task Force 4/20/2021 11 State of Practice – Survey of NCC States 21 Category Number of States Incentives / Disincentives 34 Areas of Localized Roughness 16 Specify wide laser 9 Specify wheel base for grinder 7 (5 states min. 12’, 2 states 25’) < 150 Inches per mile > 150 Inches per mile Trigger to Grinding (Preservation) 6 states 4 states State of Practice – State Specifications 22 IRI Acceptance Number of States Low Speed (<45 mph) Number of States High Speed (>45 mph) <40 inches per mile 4 40 – 60 inches per mile 4 60 – 90 inches per mile 5 20 115 – 135 inches per mile 3 10’ straight edge 3 16’ straight edge 3 4/20/2021 12 State IRI Data • Aug 2015 IGGA Case Study: https://www.igga.net/wp- content/uploads/2018/08/CSAug2015_KY_diamond_grinding_CPP_PMS.pdf • From 2007 and 2012, 536 interstate lane miles were diamond ground statewide (Louisville area) • IRI performance from 307 of the 536 lane miles was studied • After grinding, the IRI decreased from an average of 134 (in./mi.) to 64 (in./mi.) • Based on the 2019 IRI data, the average increase in IRI was 2.7 (in./mi.) per year over an average of 9.4 years after grinding. IRI > 130 in./mi. general trigger Data from Kentucky Transportation Cabinet23 State IRI Data 24 0 50 100 150 200 250 263 234 0100000000000035-D IRI LWP IRI RWP Data indicates at least a 10 year performance 0 50 100 150 200 250 266 237 IRI LWP IRI RWP 10 Years 10 Years 4/20/2021 13 State IRI Data 25 Single point lasers until 2019, Wide line lasers used in collection starting in 2020 0 20 40 60 80 100 120 140 2813 11898 IRI LWP IRI RWP 0 20 40 60 80 100 120 140 2814 11899 IRI LWP IRI RWP 10 Years 10 Years State IRI Data ‘Roller Coaster’ - may indicate a structural deficiency, fatigue or support issue Note the variance between LWP and RWP IRI 26 0 20 40 60 80 100 120 140 160 180 200 06 /3 0/ 19 83 06 /3 0/ 19 86 06 /3 0/ 19 87 06 /3 0/ 19 89 06 /3 0/ 19 91 06 /3 0/ 19 92 06 /3 0/ 19 94 06 /3 0/ 19 98 06 /3 0/ 20 00 06 /3 0/ 20 01 06 /3 0/ 20 02 06 /3 0/ 20 03 06 /3 0/ 20 04 06 /3 0/ 20 05 06 /3 0/ 20 06 06 /3 0/ 20 07 06 /3 0/ 20 08 06 /3 0/ 20 09 06 /3 0/ 20 10 06 /3 0/ 20 11 06 /3 0/ 20 12 06 /3 0/ 20 13 06 /3 0/ 20 14 06 /3 0/ 20 15 10 /1 2/ 20 16 08 /0 8/ 20 17 08 /2 7/ 20 18 08 /0 1/ 20 19 09 /0 8/ 00 21 2865 12121 IRI LWP IRI RWP 0 50 100 150 200 250 06 /3 0/ 19 83 06 /3 0/ 19 86 06 /3 0/ 19 87 06 /3 0/ 19 89 06 /3 0/ 19 91 06 /3 0/ 19 92 06 /3 0/ 19 94 06 /3 0/ 19 98 06 /3 0/ 20 00 06 /3 0/ 20 01 06 /3 0/ 20 02 06 /3 0/ 20 03 06 /3 0/ 20 04 06 /3 0/ 20 05 06 /3 0/ 20 06 06 /3 0/ 20 07 06 /3 0/ 20 08 06 /3 0/ 20 09 06 /3 0/ 20 10 06 /3 0/ 20 11 06 /3 0/ 20 12 06 /3 0/ 20 13 06 /3 0/ 20 14 06 /3 0/ 20 15 08 /0 7/ 20 17 08 /2 7/ 20 18 08 /0 1/ 20 19 09 /0 8/ 00 21 2864 12120 IRI LWP IRI RWP 4/20/2021 14 State IRI Data 27 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 2019201820172016201520142013201220112010200920082007200620052004200320022001200019991998 IR I i n/ m i Year IRI Smoothness of PCC Diamond Ground Projects Over Time 11 Years State IRI Data 28 20 40 60 80 100 120 140 160 180 201920182017201620152014201320122011201020092008 IR I in /m i Year IRI Smoothness of PCC Diamond Ground Projects Over Time 2E from 171.742 to 186.32 2E from 194 to 199.902 2E from 199.902 to 209.646 8 Years 4/20/2021 15 Evaluating Performance Many variables effecting IRI data • Traffic, age, environment, support • Panel size (curling & warping) • Load transfer (dowel bars) • Sensor type (spot laser or line laser) • Time and temperature of test 29 Evaluating Performance We know the following: • Public wants smooth pavements • Building smooth pavements stay smoother • Smoother pavements last longer • Smoother pavements are safer • Smoother pavements save money • Advancements in technology provide more accurate data Lets continue to collect and share data 30 4/20/2021 16 Achieving Smoothness • Guidelines for Specifying and Achieving Smooth Concrete Pavements, Fick, Merritt, Taylor, 2019 • Design • Construction • Measuring Smoothness • Investigation of the Effect of Curling on as Constructed Smoothness and Ride Quality of KDOT Portland Cement Concrete (PCC) Pavements, Siddique, 2004 • Constructing Smooth Concrete Pavements, ACPA wikipave https://wikipave.org/index.php?title=Constructing_ Smooth_Concrete_Pavements 31 Other Resources 32 • Real-Time Smoothness (RTS) Webinars – CP Tech Center 2020 • https://cptechcenter.org/webinars-and- videos/ • RTS Page • https://cptechcenter.org/real-time- smoothness/ 4/20/2021 17 Questions? Steve Karamihas, University of Michigan stevemk@umich.edu Jerod Gross, Snyder & Associates/CP Tech Center jgross@snyder-associates.com 334/20/2021 1 Tyler Ley, PE, PhD Professor at Oklahoma State University for 13 y Work experience with a contractor, DOT, and a consultant. Research focus – Constructability, Durability, and Novel Test methods YouTube Channel > 6M views and > 60K subscribers CONCRETE FREAK!!!! Fast-Setting Patching Materials Tyler Ley, PhD, PE 4/20/2021 2 Acknowledgements National Concrete Consortium – Pooled Fund Study Steve Tritsch FHWA – EAR - Novel Alternative Cement Binders for Highway Structures and Pavements Georgia Tech (lead) – K.E. Kurtis, L.E. Burris, and P. Alapati Oklahoma State University – M.T. Ley, J. Peery, A. Hajibabaee, and M. Khanzadeh Tourney Consulting Group (TCG) – N.R. Berke US Army ERDC – R.D. Moser Acknowledgements My daughter Isabel 4/20/2021 3 Who is your favorite super hero??? Overview of Synthesis Document Four Keys to choosing patching materials How do the patching materials work Mixing, placement, curing, grinding Comparison of patching material performance for strength and durability from literature Case studies with a focus on long term durability. Common testing protocols and specification 4/20/2021 4 Why is this talk important? 4/20/2021 5 4/20/2021 6 Rapid Patch R 4/20/2021 7 I need the strongest, fastest, most durable concrete on the planet!!!! 4/20/2021 8 Ohio DOT Research Report 134816 “In this project, the lowest cost repair material performed nearly as well as the highest price materials that cost more than 20 times as much.” Delatte et al., 2016 Concrete 4/20/2021 9 How do we know which repair material to choose??? Rapid OPC Latex modified UHPC Geopolymer Mag Phosphate Polyester Concrete Calcium sulfoaluminate (CSA) Calcium aluminate (CAC) Which one do you choose? 4/20/2021 10 Ask better questions and you will get better answers! Ask better questions and you will get better answers! 4/20/2021 11 Ask better questions and you will get better answers! There are four key questions with all repairs. Really 4/20/2021 12 The Really Fantastic Four Questions 1. How fast do you really need it open? 2. What strength do you really need? 3. Is reinforcing steel really close to the surface? 4. How long do you really need it to last? How fast do you really need it open? The longer you can delay opening the more chance you are giving the material to gain strength. This also reduces the pressure on the contractors. Less pressure = more quality = longer life 4/20/2021 13 What strength do you really need? • The lower the strength you need the easier it is to make it happen. • Reducing f’c by 500 psi can make a big difference. • Most of our repairs are over designed Super Maria!!!! 4/20/2021 14 Compressive Strength for Opening Structures 2000 – 4500 psi Wisconsin Pavements 1250 – 3500 psi Pennsylvania It was a trick question!!!! Your opening strength should be a function of the stresses in the patch. f’c1 f’c2 See early opening doc from Delatte, Weiss, Taylor 4/20/2021 15 The correct answer is it depends… Who gets extra credit? California, Georgia, Iowa, Indiana, Michigan, North Dakota, Ohio Is reinforcing steel really close to the surface? Bridge structures often have rebar close to the surface. You want your patching material to protect that steel. 4/20/2021 16 Did you know portland cement naturally protects rebar from corroding? Portland cement produces calcium hydroxide and this raises the pH of the pore solution. pH > 13 Rebar will corrode in air! But not in pH concrete 4/20/2021 17 How do you measure pH? Place a pH indicator on concrete. The most common one is phenolphthalein. pH 8 – 12 fuscia pH < 8 clear 84 d in 7% CO2 0.40 w/cm 4” x 4” Novel Alternative Cement Binders for Highway Structures and Pavements, FHWA, 2021 4/20/2021 18 84 d in 7% CO2 0.40 w/cm 4” x 4” Novel Alternative Cement Binders for Highway Structures and Pavements, FHWA, 2021 Protected Not protected 0.0 0.3 0.6 0.9 1.2 1.5 0 2 4 6 8 10 M e a n ca rb o na tio n fr o nt ( in ch e s) Square root of Exposure age (days0.5) OPC CAC2 CACT CSA2 AA Carbonation rate (in/yr0.5) OPC 0.06 CAC2 1.16 CACT 0.35 CSA2 1.72 AA 1.54 Novel Alternative Cement Binders for Highway Structures and Pavements, FHWA, 2021 7% CO2 0.40 w/cm Two months 4/20/2021 19 Most repair materials have issues with this. This means that if you have rebar 2” from the surface and the repair material is a low pH then the rebar will start corroding within the structure in < 2y!!!! The corrosion will cause cracks in your patching material and section loss in your rebar. How do repair materials compare? Good for carbonation Bad for carbonation (Good for bridges) Rapid OPC (non chloride!) CAC UHPC Geopolymer Polyester Concrete Mag phosphate Latex modified CSA 4/20/2021 20 www.youtube.com/tylerley How long do you really need it to last? As long as possible!!!! State report says 10 – 15 years. Some last +20 y. (I think this is very doable.) 4/20/2021 21 One of the keys is shrinkage! One of the keys is shrinkage! 4/20/2021 22 One of the keys is shrinkage! This causes debonding and premature cracking 4/20/2021 23 Shrinkage Basics Watch out for the CAD Monkey! 4/20/2021 24 Shrinkage Basics Watch out for the CAD Monkey! Chemical Autogenous Drying 4/20/2021 25 Shrinkage Basics type of shrinkage timing cause Chemical hours free water consumed by hydration Autogenous days hydration taking water from pores Drying months water leaving pores from drying Mixture designs Concrete mixtures with a w/cm = 0.40 and a 4” to 6” slump with 2 h to 4 h initial set time were developed. These were used for drying shrinkage testing. An equivalent paste from these mixtures were used for the other tests. 4/20/2021 26 Shrinkage Testing Chemical shrinkage ASTM C1608 (Dilatometry method) Autogenous shrinkage ASTM C1698 (Corrugated tube method) Drying shrinkage ASTM C157 (Linear drying shrinkage) Photo credit: pitt.edu PMML Chemical Shrinkage Results 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0 1 2 3 4 5 6 7 Ch em ic al S hr in ka ge (m L/ g ce m en t) Time (days) OPC CSA2 CAC2 CAC3 AA1 NO! YES! 4/20/2021 27 Chemical Shrinkage Results -50 0 50 100 150 200 250 CSA2 CAC2 CAC3 AA1 Ch em ic al S hr in ka ge R el at iv e to O PC (% D iff er en ce ) NO! YES! Autogenous Shrinkage Results 0 7 14 21 28 -4 -3 -2 -1 0 1 A ut og en ou s sh ri nk ag e (m m /m ) Hydration time (days) OPC CAC2 CAC3 CSA2 AA1 NO! YES! 4/20/2021 28 Autogenous Shrinkage Results -150 -125 -100 -75 -50 -25 0 25 50 CSA2 CAC2 CAC3 AA1 A ut og en ou s Sh ri nk ag e re la tiv e to O P C ( % ) 28 days NO! YES! Drying Shrinkage Results -900 -800 -700 -600 -500 -400 -300 -200 -100 0 0 100 200 300 D ry in g Sh ri nk ag e (m ic ro st ra in ) Time Exposed to Drying (days) OPC CAC2 CSA2 AA1 CAC3 NO! YES! Conversion Samples were wet cured for 7 days 4/20/2021 29 Drying Shrinkage Results -80 -60 -40 -20 0 20 40 D ry in g Sh ri nk ag e R el at iv e to O P C ( % d if fe re nc e) after 50 days after 150 days after 300 days CAC2 CSA2 AA1 CAC3 NO! YES! How does it compare to OPC?? Shrinkage: Chemical Autogenous Drying CSA ❌ ✓ ✓ CAC blend = = ❌ CAC ❌ ✓ ✓ AA ❌ ✓ ✓ 4/20/2021 30 What does this mean? The Geopolymer, CSA, and CAC showed a lower amount of autogenous and drying shrinkage than OPC. Less strain should mean less cracking and/or curling and warping What does this mean? These repair materials have an increase in chemical shrinkage in comparison to OPC. Based on limited concrete and paste testing no detectable damage occurred at w/cm = 0.40. Lower w/cm mixtures should be investigated. 4/20/2021 31 www.youtube.com/tylerley Can repair materials really resist freeze thaw, ASR, sulfate attack, corrosion? 4/20/2021 32 Can repair materials really resist freeze thaw, ASR, sulfate attack, corrosion? YES!!! (If they are designed right!) Novel Alternative Cement Binders for Highway Structures and Pavements, FHWA, 2021 Conclusion • Start with the really fantastic four questions to help improve your rapid patching designs. • Beware of products with low pH if you are protecting rebar. • Minimizing shrinkage is helpful and most patching materials are better at this than OPC. 4/20/2021 33 Overview of Synthesis Document Four Keys to choosing patching materials How do the patching materials work Mixing, placement, curing, grinding Comparison of patching material performance for strength and durability from literature Case studies with a focus on long term durability. Common testing protocols and specification Questions??? Tyler.ley@okstate.edu www.tylerley.com 4/20/2021 34 I I 4/20/2021 35 I Concrete | |
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| 2021-04-13 | 4/19/2021 1 Powered by NCC Spring 2021 State Reports on Fast Setting Patching Materials Thursday, April 08, 2021 Powered by Date Created: Friday, February 19, 2021 35 Total Responses Complete Responses: 35 Thank you for providing responses to the NCC survey. The information will be useful for Tyler Ley in putting together the Work Order for the 2020 Synthesis Proposal “Fast Setting Patching Materials.” Disclaimer: The data presented here is subject to interpretation of the Agency responses. Please let us know if we have errors. 4/19/2021 2 Powered by Q2: For bridge structures - Does your Agency allow/specify any of the following types of fast setting patching materials? (Check all that apply) Other: For some states, that means none of the above and other states provided additional information. State AL CA CO FL GA IA ID IL Toll IN KS KY MA MI MN MO MT NC ND NE NV NY OH OK OR PA SC SD TN TX UT WA WI WV WY Non-shrink or Shrinkage Compensating Cements (Such as Rapid Set, CSA or Type K cement) x x x x x x x x x x x x x x x x x x x x x x x x x x x Calcium Aluminate Cement (Such as Kerneos Aluminate product) or CAC cement) x x x x x x Geopolymer Cement (such as activated fly ash, material from Aquafin) x x x Magnesium Phosphate Cement (such as Phoscrete or MasterEmaco® T 545 HT) x x x x x x x x x x x x x x x x Polyester Concrete x x x x x x x x x x x x x x x x x x x Ultra High Performance Concrete (UHPC) x x x x x x x x x x Accelerated Portland Cement Concrete (by using silica fume and/or accelerating admixtures) x x x x x x x x x x x x x x x x x x x x x x Other (please specify) x x x x x x x x x x x x x Powered by Q2: For bridge structures – Does your Agency allow/specify Non-shrink or shrinkage compensating cements (such as Rapid Set, CSA, or Type k cement) YES (27) 4/19/2021 3 Powered by Q2: For bridge structures - Does your Agency allow/specify Calcium Aluminate Cement (such as Kemeos Aluminate Product or CAC cement) YES (6) Powered by Q2: For bridge structures - Does your Agency allow/specify Geopolymer Cement (such as activated fly ash, material from Aquafin) YES (3) 4/19/2021 4 Powered by Q2: For bridge structures - Does your Agency allow/specify Magnesium Phosphate Cement (Such as Phoscrete or MasterEmaco T 545 HT)? YES (16) Powered by Q2: For bridge structures - Does your Agency allow/specify Polyester Concrete? YES (19) 4/19/2021 5 Powered by Q2: For bridge structures - Does your Agency allow/specify Ultra High- Performance Concrete (UHPC)? YES (10) Powered by Q2: For bridge structures - Does your Agency allow/specify Accelerated Portland Cement Concrete (by using silica fume and/or accelerating admixtures) YES (22) 4/19/2021 6 Powered by Q3: What is your Agency's experience with fast setting patching materials for bridge repairs? Answered: 35 Skipped: 0 Powered by Q3: What is your Agency's experience with fast setting patching materials for bridge repairs (number of projects)? ≥ 5 (30) < 5 (5) None (0) 4/19/2021 7 Powered by Q4: For concrete pavements - Does your Agency allow/specify any of the following types of fast setting patching materials? (Check all that apply) Answered: 32 Skipped: 3 Other: For some states, that means none of the above and other states provided additional information. State AL CA CO FL GA IA ID IL Toll IN KS KY MA MI MN MO MT NC ND NE NV NY OH OK OR PA SC SD TN TX UT WA WI WV WY Non-shrink or Shrinkage Compensating Cements (Such as Rapid Set, CSA or Type K cement) x x x x x x x x x x x x x x x x x x x x x x x x Calcium Aluminate Cement (Such as Kerneos Aluminate product) or CAC cement) x x x x x x Geopolymer Cement (such as activated fly ash, material from Aquafin) x x x Magnesium Phosphate Cement (such as Phoscrete or MasterEmaco® T 545 HT) x x x x x x x x Polyester Concrete x x x x x x x Ultra High Performance Concrete (UHPC) x x x x Accelerated Portland Cement Concrete (by using silica fume and/or accelerating admixtures) x x x x x x x x x x x x x x x x x x x x x x x x x Other (please specify) x x x x x x x x x x Powered by Q4: For concrete pavements – Does your Agency allow/specify Non-shrink or shrinkage compensating cements (such as Rapid Set, CSA, or Type k cement) YES (24) 4/19/2021 8 Powered by Q4: For concrete pavements - Does your Agency allow/specify Calcium Aluminate Cement (such as Kemeos Aluminate Product or CAC cement) YES (6) Powered by Q4: For concrete pavements - Does your Agency allow/specify Geopolymer Cement (such as activated fly ash, material from Aquafin) YES (3) 4/19/2021 9 Powered by Q4: For concrete pavements - Does your Agency allow/specify Magnesium Phosphate Cement (Such as Phoscrete or MasterEmaco T 545 HT)? YES (8) Powered by Q4: For concrete pavements - Does your Agency allow/specify Polyester Concrete? YES (7) 4/19/2021 10 Powered by Q4: For concrete pavements - Does your Agency allow/specify Ultra High-Performance Concrete (UHPC)? YES (4) Powered by Q4: For concrete pavements - Does your Agency allow/specify Accelerated Portland Cement Concrete (by using silica fume and/or accelerating admixtures) YES (25) 4/19/2021 11 Powered by Q5: What is your Agency's experience with fast setting patching materials for concrete pavement repairs? Answered: 35 Skipped: 0 Powered by Q5: What is your Agency's experience with fast setting patching materials for concrete pavement repairs (number of projects)? ≥ 5 (31) < 5 (2) None (2) 4/19/2021 12 Powered by Q6: Does your Agency allow volumetric mixers for batching fast setting patching materials? Answered: 35 Skipped: 0 Powered by Q6: Does your Agency allow volumetric mixers for batching fast setting patching materials? YES (26) NO (9) 4/19/2021 13 Powered by Q7: Does your Agency modify any repair details when using fast setting patching materials? YES (15) NO (17) Powered by Q7: Does your Agency modify any of the following requirements when using fast setting patching materials? (Check all that apply) State AL CA CO FL GA IA ID IL Toll IN KS KY MA MI MN MO MT NC ND NE NV NY OH OK OR PA SC SD TN TX UT WA WI WV WY None of the above x x x x x x x x x x x x x x x x x Curing x x x x x x x x x x x x Repair Size x x Full Depth or Partial Depth Repair x x x Surface Preparation x x x x x x x Use of reinforcement x x 4/19/2021 14 Powered by Q8: Does your Agency require field testing on the fast setting patching materials? (Check all that apply) YES NO Powered by Q8: Does your Agency require field testing on the fast setting patching materials? (Check all that apply) State AL CA CO FL GA IA ID IL Toll IN KS KY MA MI MN MO MT NC ND NE NV NY OH OK OR PA SC SD TN TX UT WA WI WV WY None of the above x x x x x x x x Air Content x x x x x x x x x x x x x x Slump x x x x x x x x x x x x Compressive Strength x x x x x x x x x x x x x x x x x x x x x x x Flexural Strength x x x x x x Other x x x x x x 4/19/2021 15 Powered by Q9: Does your Agency require performance testing prior to approving fast setting patching materials? (Check all that apply) YES NO Powered by Q9: Does your Agency require performance testing prior to approving fast setting patching materials? (Check all that apply) Answered: 34 Skipped: 1 State AL CA CO FL GA IA ID IL Toll IN KS KY MA MI MN MO MT NC ND NE NV NY OH OK OR PA SC SD TN TX UT WA WI WV WY None of the above x x x x x x x Freeze-Thaw x x x x x x x x x x x x x x x x x x Shrinkage x x x x x x x x x x x x x x x x x x x x x x Strength x x x x x x x x x x x x x x x x x x x x x x x x x x Other x x x x x x x x x x x x 4/19/2021 16 Powered by Q10: Has your Agency diamond ground any of the fast setting patching materials? Answered: 35 Skipped: 0 Powered by Q10: Has your Agency diamond ground any of the fast setting patching materials? YES (18) NO (17) 4/19/2021 17 Powered by Q10: Any performance issues after diamond grinding? Did you have to modify any of the diamond grinding specifications? AL I'm sure patched sections of pavement have been ground as part of a rehab project, but in Alabama, any ground pavement would be covered with OGFC or similar. So it would be difficult to assess if we have any performance issues after grinding. CA Given the friction requirements, it is mentioned in Section 60-4.02C of Standard Specification to grind or groove surfaces having a coefficient of friction less than 0.35. It is understood this means that grinding/grooving can be considered as a viable option as necessary. Not sure if grinding specifications need to be modified. No specific requirements could be found in Section 42 of Standard Specifications. FL High early ready mix concrete typically for slab repairs. Depends on area of repair. No known issues related to diamond grinding. IL Toll We've diamond grinded a few small areas and didn't have issues. KY Not certain concerning issues encountered or any modifications. MI Patching with non-cementitious materials has been relatively small compared to the total grinding surface, therefore no problems have emerged at this time. If they become more prevalent it is possible a modification will be required. Standard fast sets and full depths have not required special modifications. MN no problems with grinding. we do chain all the pdr's after the grind to determine if the UHE remains bonded after the grinding. We always seem to find a few repairs that are not bonded. the Contractor would then need to remove and replace those repairs that are not bonded at their expense. FYI my experience with UHE concrete patch mix is, UHE concrete backfill is by far more prone to shrinkage cracks. Cracks that would required removal and replacement when utilizing MnDOT's standard repair mix, PDR's that are not bonded always require removed and replaced at the Contractors expense. MO The diamond grinding specifications were not modified. Have not had any issues to date. NV A recent example is grinding down patches for spalls on new PCCP to meet pavement smoothness and IRI specifications NY We has diamond ground UHPC. I'm not aware of any performance issue after UHPC has been diamond ground. OH Followed our Proposal Note 420. Structures is Proposal Note 555. PA The contractor had issues with the fast setting patching material cracking shortly after being diamond ground. What was discovered was the contractor never added the #8 aggregate extender to the mix because the repair depth was in excess of 2”. Once the contractor started adding the aggregate extender to the patches greater than 2” in depth they cracking issue disappeared. SC I would imagine that has occurred in our state, but I don't have any specific information on such. SD All spall repairs have to be completed before diamond grinding the surface on rehab projects. No issues noted using standard diamond grinding. TX No performance issues that we are aware of after grinding. No modifications to grinding specs. UT Three questions with only one response. Yes, we have diamond ground fast setting patches. No, it issues after diamond grinding. No modifications to the specifications. WA No performance issues have been identified. Powered by Q11: Do you allow calcium chloride in any patching repair materials? Answered: 35 Skipped: 0 4/19/2021 18 Powered by Q11: Do you allow calcium chloride in any patching repair materials? YES (11) NO (24) Powered by Q12: How does your Agency handle the approval of fast setting patching materials if used in your state? NTPEP (11) Agency Req. (22) Producer (2) NTPEP (Horizontal) Agency Req. (Vertical) 4/19/2021 19 Powered by Q13: What strength does your Agency require patches to achieve before they are open to traffic? If different for bridges and structures, please indicate. Answers varied: • Compressive and/or Flexural Strength • Strength and Time • Time • Pavement repair length • Bridge Design Strength Powered by Disclaimer: This is a subset of the results. Some of the strengths charted have additional conditions. Q13: What strength does your Agency require patches to achieve before they are open to traffic? If different for bridges and structures, please indicate. 4/19/2021 20 Powered by Q13: What strength does your Agency require patches to achieve before they are open to traffic? If different for bridges and structures, please indicate. AL Bridges: 2400 psi or 6 hours. Pavement: 3000 psi or 6 hours. CA Section 51-5.01D(2)(b): For approach slabs; trial slab concrete must develop the following minimum compressive strengths: 1. 1,200 psi at the age of break 2. 2,500 psi at 3 days 3. 4,000 psi at 28 days 400 psi MOR for paving applications. CO 2500 psi for pavement Depends on bridge structure FL Prepackaged - Manufacturer's recommendations or as specified in the Project Plans. High early ready mix - 1600 psi for pavement, design strength for bridge decks. GA 2500 psi for standard 24 hour mix. 3000 psi for 4 hour mix with Rapid Setting Cement IA Pavements M-Mix w CaCl 2 Lane - 5 hours 4 Lane - 10 hours M-Mix w/o CaCl -24 hours When rapid set patch materials used time may be reduced to 2-3 hours depending on traffic volumes. Structure - varies ID 2,500 psi IL Pavement patches can be opened at 250 psi flexural or 1600 psi compressive. Bridge deck patches have to cure for 72 hours and achieve 675 psi flexural or 4000 psi compressive. IL Toll 2,500 psi and 4,000 psi compressive strength for pavement and structures, respectively. IN For PCCP patches less than or equal to 15 LFT, 300 psi flexural. For PCCP patches greater than 15 LFT, 425 psi flexural. Bridge deck patching, 550 psi flexural Powered by Q13: What strength does your Agency require patches to achieve before they are open to traffic? If different for bridges and structures, please indicate. KS Flexural = 380 psi or F'c = 1800 psi. KY 3000psi or based on project specific notes. MA AASHTO T 22 Compressive Strength: For the most part, 2500 psi seems to be a common parameter in the special provisions. MI Structures: Must meet a minimum flexural strength of 550 psi and must meet the required curing time (curing time is dependent on the material). Pavements: For rapid patches (scheduled Opening <72 hours) must meet minimum flexural strength of 300 psi For standard patches (scheduled Opening >=3 days) must meet minimum flexural strength of 550 psi MNPartial depth repairs on bridges and PCCP require 3000 psi prior to opening to construction equipment or opening to the public. Full depth repairs require 2000 psi prior to opening to either construction equipment or public travel. MOFull Depth Pavement Repairs - 2,000 psi Partial Depth Pavement Repairs - 1,600 psi Bridge Structures - 3,200 psi MT 3000 PSI NC 3000 psi ND Product specific, protected as long as possible from traffic then opened. NE 3000 psi for pavement - 4000 psi for bridge decks. 4/19/2021 21 Powered by Q13: What strength does your Agency require patches to achieve before they are open to traffic? If different for bridges and structures, please indicate. NV The same strength as the existing structure, typically 4,500 psi NY We require 3000 psi to open a bridge deck and 2500 psi to open a pavement. OH 400 psi flexural in 4 hours. OK 3,000 psi OR Patches require 2,500 psi prior to returning to traffic. PA 1200 psi SC Our specifications do not allow loading of the concrete until it meets 90% of the design strength. Therefore, generally bridge decks are 4000 psi concrete, so the patch would have to meet 3600 psi. Concrete pavement is 4000 or 5000 psi, so the patch would have to meet 3500 or 4500 psi. SD 3,000 psi for pavement partial depth patches. TN 3000 psi for bridge structures and new concrete pavements. 2500 psi for pavement repairs. Powered by Q13: What strength does your Agency require patches to achieve before they are open to traffic? If different for bridges and structures, please indicate. TX 1800 psi compressive strength for concrete pavement. 4000 psi for bridge decks. UT 3500 psi WA 2,500 psi for both bridge and pavement. WI 2000 psi compressive strength WV 2,000 psi (13.8 Mpa) prior to the time at which the pavement will be opened to traffic WY Typically 3000 psi 4/19/2021 22 Powered by Q14: If your Agency has installed any fast setting patching materials, what is the longest installed patches still in service and performing acceptably. Answers ranged from: • Unknown or Not sure • 5 years • 5 – 10 years • 7 years • 10+ years Some success stories listed (Tyler Ley may contact you for further information) Powered by Q14: If your Agency has installed any fast setting patching materials, what is the longest installed patches still in service and performing acceptably. AL For pavements, Fibercrete has been used extensively in the Birmingham Area. For Bridges, XJS expansion joint system repairs have been extensively used. Cases of both of these products have been in service for 10+ years now without issue. CA No data, but usually expect 5-10 years of service life. CO There is no tracking system to determine age of patches. FL No data. GA Not sure. Very limited use. IA No data available ID Not Sure. IL We still have some calcium-aluminate cement patches (Class PP-5 concrete) installed in 2008 in service on I-94/Edens Expressway. IL Toll About 5 years, but we might have some that have been out there for longer. IN Unknown 4/19/2021 23 Powered by Q14: If your Agency has installed any fast setting patching materials, what is the longest installed patches still in service and performing acceptably. KS If they stay 5 years we're lucky. KY Not sure. MA Not sure, but the rapid set concrete patch materials are always thought of as "temporary" while the volumetric mixer rapid hardening concrete repairs are thought of as more permanent. MI A Cementitious mix with a low w/c ratio and a strength/hardening admixture (type S):10 years Standard hydraulic patches: 5 years Non-cementitious patches: 10 years MN 2009 the UHE ready mix used in full depth repairs are performing no differently than a standard mix. Regarding partial depth repairs, on this project, the UHE backfill is exceeding every expectation I had. yes some PDR's have failed and been patched with bit. But, I would say the UHE patch mix material used on this project is preforming nearly as well, if not as well as MnDOT's standard PDR patch mix. But I have used other types of prebagged UHE mixtures that have not performed nearly as well. My belief is some bagged UHE are susceptible durability issue when the Contractor exceeds the recommend water content. On a project constructed in 2011, the same Contractor used two different UHE mixes extended at 50% by mass and the same source of aggregate. Even though both mixes pass the testing requirement out lined in question 12, the durability performance was not the same. The same mix used on the 2009 project performed very well. The second bagged UHE mix did not perform nearly as well. The second mix had severe freeze thaw damage after 10 years. MO Full Depth Concrete Pavement - 15 years Powered by Q14: If your Agency has installed any fast setting patching materials, what is the longest installed patches still in service and performing acceptably. MT NA NC Not sure ND Not tracked or known, normally major repair projects are completed to repair them within 5-7 years on structures. NE 20 years would be the max NV Polymer concrete patches tend to typically last 10-15 years NY Typical fast setting bagged patching material used to repair a bridge deck last between 5 and 10 years on average. It's unknown how long the oldest one is. The cementitious component of the repair material like Calcium Aluminate Cement used through a volumetric mixer with State approved sand and coarse has been shown to last 25+ years. OH unsure. Most patches are in for about 5 to 10 years to aid as a band aid prior to selling a larger project. OK Not sure. OR Unknown, >10 years 4/19/2021 24 Powered by Q14: If your Agency has installed any fast setting patching materials, what is the longest installed patches still in service and performing acceptably. PA 10+ years SC I don't have that information. SD Unknow for sure. There may be some still in place 15 to 20 years later. We changed to using mostly MNDOT 3U58M materials for spall repairs since we had a high initial failure rate using ASTM C928 Type 3 materials. TN N/A TX Some patch are over at least over 10 year old and still performing satisfactorily. UT 7 years WA Unknown WI Not known WV Aquafin Pavement DOT Line, This product seems to work well when no flexure is involved. We have had it in place for 5 years in a back wall repair and it still seems to be performing well. It works well for patching also but is a little hard to finish. We have patches in place that are 2.5 years old and still ok. WY Probably a few latex overlay lasting 30+ years but not typical Powered by Q15: Does your Agency have any research either in progress or complete on fast setting repair materials? Answered: 35 Skipped: 0 4/19/2021 25 Powered by Q15: Does your Agency have any research either in progress or complete on fast setting repair materials? YES (13) NO (22) NRRA conducted a study at MnROAD involving field performance of different fast setting repair materials. Powered by Q15: Does your Agency have any research either in progress or complete on fast setting repair materials? IL We will be starting a research project looking into non-proprietary UHPC/VHPC in August 2021. IL Toll We are wrapping up a brief report on a fast set concrete partial depth bridge deck patching test section we installed in July 2017. The test section was the basis for our approved product list. IN SPR-2141 (2001) Purdue University - Development and Evaluation of Cement-based Patching Materials for Repair of Corrosion- Damaged Reinforced Concrete Slabs SPR-3019 (2012) Purdue University - Field Trial of Rapid Setting Patch Materials KS Current K-Tran study with Kansas State University & Research. MA Perhaps not exactly research, but we do have plenty of test data from over the 10 plus years we've utilized these materials. MI We have researched a wide range of fast setting repair mixtures. Some of the more recent materials the Department has worked with are concrete mixtures using a low w/c and a strength/hardening type S admixture, Polyester Concrete, and MMA Polymer Concrete. For more details on what the Department has worked with please feel free to contact me. MO Please be advised that the NRRA conducted a study involving field performance of different fast setting repair materials. NE The university completed a research project on the DOT mix design. Materials & Research is currently looking at the proposed mixes and will have a trial project in 2021. NY We have not specifically performed research on our own but we do use the NTPEP RSCP Test Deck as a resource. OR Oregon State University is performing research on CSA and CAC cements for bridge deck overlays. A supplemental outcome of the research will likely be additional information regarding patching materials. The research is in the early phase of material acquisition. Many of the materials identified for the study are bagged fast setting repair materials. SC We are conducting research that will help us specify long lasting rapid set bridge deck patches. TX https://library.ctr.utexas.edu/ctr-publications/0-6723-1.pdf UT WY Conducted research on silica fume modified concrete overlays 4/19/2021 26 Powered by Q16: Please provide a link to the specifications for concrete patching repair materials (include both fast setting and traditional). AL Section 453 https://www.dot.state.al.us/conweb/pdf/Specifications/2018StandardSpecificationsCompleteBook.pdf List III-2 Evaluation & Maintenance Procedure: https://www.dot.state.al.us/mtweb/Testing/MSDSAR/pdf/Pro/Piii02.pdf CA The standard specifications can be found using the following link: https://dot.ca.gov/programs/design/ccs- standard-plans-and-standard-specifications Please review sections 41, 51, 60, and 90 for requirements of rapid strength and normal concrete. CO ASTM C1600 for CSA cements ASTM C928 for general packaged patching materials Bridge deck patching: https://www.codot.gov/business/designsupport/cdot-construction-specifications/2019-construction- specifications/rev-ssp/rev-sec600/rev-601-cdejc FL https://fdotwww.blob.core.windows.net/sitefinity/docs/default- source/programmanagement/implemented/specbooks/july2021/7-21ebook.pdf?sfvrsn=9a1c9abf_4 Sections 346, 353, 926, 930 GA http://www.dot.ga.gov/PartnerSmart/Business/Source/specs/2021StandardSpecifications.pdf IA Pavement - Full depth https://iowadot.gov/erl/current/GS/content/2529.htm Pavement - Partial depth https://iowadot.gov/erl/current/GS/content/2530.htm Structural Repair https://iowadot.gov/erl/current/GS/content/2426.htm ID https://apps.itd.idaho.gov/Apps/manuals/SpecBook/SpecBook18.pdf Powered by Q16: Please provide a link to the specifications for concrete patching repair materials (include both fast setting and traditional). IL Refer to our Standard Specifications: https://idot.illinois.gov/Assets/uploads/files/Doing-Business/Manuals- Guides-&-Handbooks/Highways/Construction/Standard- Specifications/Standard%20Specifications%20for%20Road%20and%20Bridge%20Construction%202016.pdf Section 442: Pavement Patching Article 1001.01(d): Rapid Hardening Cement (updated, see below) Article 1001.01(3): Calcium Aluminate Cement (updated, see below) Section 1020: Portland Cement Concrete (updated, see below) Updates to Article 1001.01(d) and Section 1020: https://idot.illinois.gov/Assets/uploads/files/Doing- Business/Specialty-Lists/Highways/Design-&-Environment/BDE-Special-Provisions/80431.pdf Update to Article 1001.01(3): https://idot.illinois.gov/Assets/uploads/files/Doing-Business/Manuals-Guides-&- Handbooks/Highways/Construction/Supplemental-Standards- Specifications/2021%20Supplemental%20Specifications%20for%20Website.pdf IL Toll The Tollway's special provisions are not posted online, but can be made available upon request. IN https://www.in.gov/dot/div/contracts/standards/book/sep19/sep.htm See sections 901.07 and 901.08 KS https://www.ksdot.org/bureaus/burConsMain/specprov/2015specprov.asp KY https://transportation.ky.gov/Materials/Documents/LAM.PDF MA There is no standard as of yet, however, I am working with industry to develop a standard specification. For those how want to reach out for an information on that, they may reach me at richard.mulcahy@dot.state.ma.us. 4/19/2021 27 Powered by Q16: Please provide a link to the specifications for concrete patching repair materials (include both fast setting and traditional). MI https://mdotjboss.state.mi.us/SpecProv/specBookHome.htm Look at Division 603 for pavement repairs. Look at Division 702 and 703 for structural repairs. MN http://www.dot.state.mn.us/products/concrete/pdf/MnDOTApprovedPackagedDryNon-ShrinkRapid- HardeningConcreteProcedures2018.pdf The testing requirements to place a DBR backfill product on the MnDOT's APL are the same as what MnDOT would require for a UHE product used for backfilling PDR's. In other words, If a UHE product is on MnDOT's APL for dowel bar retrofits, that product also could also be used to backfill PDR's. Standard CPR Spec. S-145 (2302) CONCRETE PAVEMENT REHABILITATION (CPR) http://www.dot.state.mn.us/pre-letting/prov/index.html MO Link to MoDOT's Standard Specifications is shown below: https://www.modot.org/sites/default/files/documents/2020%20Missouri%20Standard%20Specific%20- %20MHTC%20%28April%202021%29.pdf Section 613 Pavement repairs Section 704 Concrete Masonry Repairs Rapid Set Patching Material - Horizontal JSP-02-10 https://spexternal.modot.mo.gov/sites/de/_layouts/15/WopiFrame.aspx?sourcedoc={6483C083-3678-489B- B59B-AF6303A60814}&file=JSP0210.doc&action=default Rapid Setting Patching Materials - Overhead & Vertical JSP-02-01 https://spexternal.modot.mo.gov/sites/de/_layouts/15/WopiFrame.aspx?sourcedoc={30AF5C32-7AD8-4B69- B282-0B68FED4910A}&file=JSP0201.doc&action=default MT MDT specifications are fairly vague currently. Powered by Q16: Please provide a link to the specifications for concrete patching repair materials (include both fast setting and traditional). NC N/A ND http://mydot.nd.gov/manuals/maintenance/70mtc_opr_manual.pdf NE Standard Specifications for Highway Construction - Section 1002 https://dotstore.nebraska.gov/storefront/Store/tabid/78/CatID/8/Publications.aspx NV https://www.dot.nv.gov/home/showpublisheddocument?id=6916 Section 502.03.15 NY https://www.dot.ny.gov/main/business-center/engineering/specifications/ english-spec repository/2021_5_specs_usc_tc_vol4.pdf Standard Specifications 701-04, 710-09, and 701-12 are fast and normal setting bagged repair materials. Standard Specification 701-13 is for Rapid Hardening Hydraulic Cement. OH https://www.dot.state.oh.us/Divisions/ConstructionMgt/OnlineDocs/Pages/2019-Online-Spec-Book.aspx OK None OR https://www.oregon.gov/odot/Business/Pages/Special-Provisions.aspx PA http://www.dot.state.pa.us/public/PubsForms/Publications/Pub_408/408_2020/408_2020_IE/408_2020_IE.pdf Sections 516, 525,1046, and 1047 list specifications for approved materials for concrete patching on pavement and bridge decks. 4/19/2021 28 Powered by Q16: Please provide a link to the specifications for concrete patching repair materials (include both fast setting and traditional). SC Basically the QPP is the specification for the rapid set concrete pavement patching materials. http://info2.scdot.org/Materials/QualProd/22%20QPP.pdf There is no specification for rapid set bridge deck patching materials. We currently specify standard concrete for bridge deck patching in our Standard Specifications. SD Section 390 for PCCP spall repair https://dot.sd.gov/doing-business/contractors/standard- specifications/2015-standard-specifications TN https://www.tn.gov/content/dam/tn/tdot/hq-materials-tests/qpl/List_13.pdf TX https://ftp.txdot.gov/pub/txdot-info/cst/DMS/4000_series/pdfs/4655.pdf UT Specifications https://drive.google.com/file/d/1TQu03yV5JN5kU7BzFD01GoNb1uUhO3rg/view?usp=sharing Traditional repair Section 02751 Partial Depth Repair for Concrete Pavements. Section 2753 Full Depth Slab Replacement for Concrete Pavements Section 03934 Structural Pothole Patching We do have a special provision that we are taking soon to our standards committee for approval as a standard. We can make that available. Powered by Q16: Please provide a link to the specifications for concrete patching repair materials (include both fast setting and traditional). WA https://www.wsdot.wa.gov/publications/manuals/fulltext/M41-10/SS.pdf See section 9-20.1 for concrete pavement patching material and 9-20.5 for bridge deck patching material. WI Don't know how to do links WV https://transportation.wv.gov/highways/contractadmin/specifications/Documents/2021_Supplemental_2020 1208%20(redline).pdf Section 715.4 Section 600 Section 501 &506 https://transportation.wv.gov/highways/contractadmin/specifications/2017StandSpec/Documents/2017_Sta ndard.pdf Section 715.4 Section 600 Section 501 &506 WY Section 810 Concrete Repair of Standard Specification http://www.dot.state.wy.us/files/live/sites/wydot/files/shared/Construction/2021%20Standard%20Specifica tions/Wyoming%202021%20Standard%20Specifications%20for%20Road%20and%20Bridge%20Construction. pdf Fast setting patching handled by special provisions, links not available 4/19/2021 29 Powered by Q17: Please provide a link to the APL/QPL for all of your Agency's concrete patching repair materials. AL https://www.dot.state.al.us/mtweb/Testing/MSDSAR/pdf/QMSD/Liii02.pdf CA https://dot.ca.gov/programs/engineering-services/authorized-materials-lists CO https://apps.codot.gov/apl/AplSearch.cfm?SelectBy=Cat&cid=Concrete&scid=Repair/Patching FL https://fdotwp1.dot.state.fl.us/ApprovedProductList/Specifications?specificationRange=900&IsDevSpec=False 926 and 930 GA http://www.dot.ga.gov/PartnerSmart/Materials/Pages/QPL.aspx IA https://maple.iowadot.gov/Search.aspx Material Names search for CONCRETE REPAIR, RAPID SET PATCH MATERIALS CONCRETE REPAIR, FAST SET STRUCTURAL REPAIR MORTAR ID https://apps.itd.idaho.gov/Apps/Materials/QPL.aspx IL PACKAGED, DRY, RAPID HARDENING CEMENTITIOUS MATERIALS FOR CONCRETE REPAIRS: https://idot.illinois.gov/Assets/uploads/files/Doing-Business/Specialty-Lists/Highways/Materials/Materials-&- Physical-Research/Concrete/rapidhardeningconcrete.pdf RAPID HARDENING CEMENT: forthcoming IL Toll https://www.illinoistollway.com/documents/20184/239415/ApprovedFastSetConcreteList.pdf/814081c7-4b31- 45f7-a28a-6b2ea6cf60ae?version=1.1&t=1539713412473&download=true IN https://www.in.gov/indot/div/mt/appmat/pubs/apl30.pdf KS https://www.ksdot.org/bureaus/burMatrRes/PQL/default.asp Powered by Q17: Please provide a link to the APL/QPL for all of your Agency's concrete patching repair materials. KY https://transportation.ky.gov/Materials/Documents/LAM.PDF The KY LAM is in need of updating to comply with NTPEP submittal. MA https://www.mass.gov/service-details/rapid-set-concrete-patch-materials-horizontal-verticaloverhead https://www.mass.gov/service-details/approved-cement-concrete-producer-contact-information https://www.mass.gov/info-details/cement-concrete-producers-approved-mix-designs MI https://www.michigan.gov/documents/mdot/2021_January_MSG_Final-with_Links_708873_7.pdf look at sections:702.02B for Non-Shrinking Mortar and Grout Type H-1 (Non-Metallic) Pre-Mixed and 703 for Prepackaged Hydraulic Fast Set Mortar MN http://www.dot.state.mn.us/products/concrete/pdf/MnDOTApprovedPackagedDryNon-ShrinkRapid- HardeningConcreteProcedures2018.pdf Qualification process for DBR concrete backfill is the same as what would be required if the project required UHE concrete for PDR's MO Rapid Set Patching Material List - Horizontal https://www.modot.org/sites/default/files/documents/FS704T1_5.pdf Rapid Setting Patching Materials List - Overhead & Vertical https://www.modot.org/sites/default/files/documents/FS704T2_2.pdf MT NA 4/19/2021 30 Powered by Q17: Please provide a link to the APL/QPL for all of your Agency's concrete patching repair materials. NC https://apps.ncdot.gov/vendor/approvedproducts/Default.aspx ND • Ceratec Pavemend VR™ • SpecChem RepCon® V/O • Sika® SikaQuick® VOH • BASF MasterEmaco® N425 NE https://dot.nebraska.gov/business-center/materials/approved-products/ NV https://www.dot.nv.gov/home/showpublisheddocument?id=18262 NY https://www.dot.ny.gov/divisions/engineering/technical-services/technical-services- repository/alme/NYSDOT_Approved_List.pdf OH https://www.dot.state.oh.us/Divisions/ConstructionMgt/Materials/Pages/QPL.aspx https://www.dot.state.oh.us/Divisions/ConstructionMgt/Materials/Approved-List/Pages/default.aspx https://www.dot.state.oh.us/Divisions/ConstructionMgt/Specification%20Files/PN420_01172020_for_2019.pdf https://www.dot.state.oh.us/Divisions/ConstructionMgt/Specification%20Files/PN555_01152021_for_2019.pdf OK Not on APL OR https://www.oregon.gov/odot/Construction/Doc_ProductReview/pcc_repair.pdf PA http://www.dot.state.pa.us/public/pdf/bocm_mtd_lab/publications/pub_35/current_edition/bulletin15.pdf Sections 516, 525,1046, and 1047 list approved materials for concrete patching on pavement and bridge decks. SC http://info2.scdot.org/Materials/QualProd/22%20QPP.pdf SD N.A. Powered by Q17: Please provide a link to the APL/QPL for all of your Agency's concrete patching repair materials. TN https://www.tn.gov/tdot/materials-and-tests/research---product-evaluation-and-qualified-products-list.html TX https://ftp.txdot.gov/pub/txdot-info/cmd/mpl/concrepair.pdf UT Materials Authorized Products https://www.udot.utah.gov/connect/business/materials-qualification- programs/materials-authorized-products/ WA https://wsdot.wa.gov/biz/mats/QPL/QPL_Search.cfm For pavement patching material select section 9-20.2 in the Standard Spec. field. For bridge deck patching material select section 9-20.5 in the Standard Spec. field. WI Don't know how to do links WV https://transportation.wv.gov/highways/mcst/Documents/2020%20APL/PCC/10-20- 2020%20Approved%20List%20of%20Concrete%20Repair%20Materials.pdf WY http://www.dot.state.wy.us/files/live/sites/wydot/files/shared/Materials/Qualified%20Products/Qualified%2 0Products%2008_28_2019.pdf 4/19/2021 1 Mike Praul is the Senior Concrete Engineer with FHWA 34 years with FHWA Manages Mobile Concrete Technology Center program and leads FHWA’s PEM initiatives Lives in Augusta, ME with wife Jody Loves dachshunds About the Speaker Image Here Office of Infrastructure M I C H A E L F . P R A U L , P E S E N I O R C O N C R E T E E N G I N E E R F H W A , O F F I C E O F I N F R A S T R U C T U R E FHWA Program Update National Concrete Consortium, Spring 2021 Meeting April 13, 2021 FHWA is the source of all images in this presentation unless otherwise noted. 4/19/2021 2 Pavement and Materials Program Areas PEM Implementation Incentive 19 States + FHWA & Industry (November 2020) Performance-Engineered Mixtures (PEM) Implementation Incentive Pilot Project 4/19/2021 3 PEM approach is beneficial to State and industry PEM mix tested better in all tests vs. Class C 2nd supplier was reluctant to participate Determined QC requirements were not much more than they currently do Mix looked and placed better than Class C Needs Training in new tests Understanding roles and responsibilities in a performance specification (including QC monitoring) Consider 56-day testing for resistivity Developing next project in NYC area (structural) New York Project Highlights New York Surface Resistivity Testing 4/19/2021 4 Box Test Highly useful in mix development and evaluation (contractor) Simple, easy test. Potential to add to specification (NCDOT) Super Air Meter After some training, readily incorporated into quality control (QC) (contractor) Doing more shadow testing and consider future use (NCDOT) Surface Resistivity Easy. Readily incorporated into QC (contractor) Easy. Affordable equipment. Will equip all State labs. (NCDOT) UNC-Charlotte working to develop 28-day result to correlate with 56-day results North Carolina Project Highlights “Valuable experience” (contractor and NCDOT) “Due to project schedule, we were unable to apply the PEM criteria during the preliminary mix design phase. However, going forward, we intend to implement PEM guidelines on future PCCP (portland cement concrete pavement) projects.” (contractor) “The Department will continue to explore PEM to see how these tests and other AASHTO PP 84 provisions will work with our daily operations.” (NCDOT) NCDOT will pilot PEM bridge project. North Carolina Project Highlights 4/19/2021 5 Box Test: 45#/cy reduction in cement Contractor now using to develop mixes Super Air Meter comments Need for technician training Attention to detail for correlation testing Concern with gauge durability Surface Resistivity Invaluable information for agency and industry Easy to perform, no changes needed Expanded typical QC requirements without issue 2020 project use proposed by contractor. Approved! Iowa Project Highlights • Collaboration with MCTC • Comparison of conventional and performance engineered concrete mixtures Iowa Impact Analysis Std mixes PEM 4/19/2021 6 • TRACI 2.1 by the U.S. Environmental Protection Agency • Impact categories: o Acidification potential (AP) o Eutrophication potential (EP) o Global warming potential (GWP) o Ozone depletion potential (ODP) o Smog creation potential (SCP) Life Cycle Impact Assessment Preliminary Results: Mixture Comparison • Reduction of cement by 36 lbs/yd3 → 7% savings in all impacts. • Reduction of cement by 64 lbs/yd3 → 10- 14% savings in all impacts. 0.5 0.6 0.7 0.8 0.9 1 AP EP GWPODP SCP BAU1 BAU2 PEM 4/19/2021 7 Total Savings: Shoulder Total CO2-eq savings • 1 m3 of concrete= 21 kg. • Shoulder (6’ by 8”- Iowa project from 2019)= 12.4 t/ mile. Source: https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator Total Savings: Main Line + 2 Shoulders per Mile Total CO2-eq. savings: • Shoulder (6’ and 10’ by 8”- Iowa project from 2020)= 33.1 t. • Main lane (12’ by 11”- Iowa project from 2020)=34.1 t • TOTAL= 67.2 t Source: https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator 4/19/2021 8 FHWA Mobile Concrete Technology Center (MCTC) Program Live training Virtual tours (conference) Training video briefs: “how-to’s” of MCTC equipment being deployed • Turner-Fairbank Highway Research Center collaboration • Equipment Loan Program • Technical assistance/data analysis • Specification reviews • Technical publications 2020 Program Activities 4/19/2021 9 “Live From the MCTC” Training/Workshops Super Air Meter (SAM) Surface/Bulk Resistivity Maturity Box Test/V-Kelly Semi-adiabatic calorimeter “Live From the MCTC” Topics Phoenix (fresh water content) MIT Scan T3 MIT Dowel Scan HIPERPAV Optimized gradation software 4/19/2021 10 “I was at the MO/KS ACPA workshop and the Live Tour of the MCTC was absolutely fabulous - clear, informative, and felt like we were together (as much as 2021 could allow anyway). Jim & Josh did a fantastic job leading this effort!” Jesse Jonas ACPA-Missouri Endorsement One-Pager Series Effort to use MCTC data and experience Narrowly focused Meant to stir interest and point reader to resources 1st : Cement Content 2nd : Optimized Mix Design 3rd : Cores vs. Cylinders 4th : NDT Thickness Measurement 5th : Surface Resistivity 6th : Texture of Concrete Pavements 7th : Maturity 8th : Curing 9th : Workability 10th: Air Entrainment 11th : Stringless Paving 4/19/2021 11 TFHRC Update Identify implementation-ready technologies to provide a tool to quantify if curing best practices are followed. Curing Quantification Contact: Robert.Spragg@dot.gov 4/19/2021 12 AASHTO COMP 3C Task Force 20-01: Resistivity 19 members (8 DOTs & Others) Meeting since November 2020 Harmonization where applicable Consensus on how to specify curing Specifically looking at the “Bucket Test” Proportions vs. measurement of solution On going efforts at FHWA are looking to see if strength/resistivity can be conducted on same specimens in curing solution AASHTO Resistivity Task Force Contact: Robert.Spragg@dot.gov 0 5 10 15 20 25 30 35 40 g C A O X Y Accelerated Curing To Determine Transport Properties Extension of Existing Tests Increased Accessibility of Calcium Oxychloride Testing Montanari, et al. (2020). Quantification of Calcium Oxychloride by Differential Scanning Calorimetry: Validation and Optimization of the Testing Procedure. Submitted to Advances in Civil Engineering Materials. Montanari, et al. (2021). Accelerated Curing of Concrete Mixtures for Resistivity and Formation Factor Evaluation. In Preparation. 0 2 4 6 8 10 12 14 0 10 20 30 40 C a lc iu m H yd ro xi d e C o nt e nt [g /1 00 g ] SCM Mass Replacment [%] Standard Curing (91d) Contact: Robert.Spragg@dot.gov 4/19/2021 13 Is your agency experiencing premature joint deterioration in concrete pavements or interested if CaOXY evaluation might be a useful addition to your pavement program? Robert.Spragg@dot.gov Alkali Aggregate Reactions in Concrete Alkali-Silica & Alkali-Carbonate Research Highway Materials & Aggregates in – Concrete, Asphalt, & Granular Bases Several University Exploratory Advanced Research (EAR) and Small Business Innovative Research (SBIR) Projects on Fly Ash & the Quality of Entrained Air-Voids in Concrete Provide Forensic Microscopy Help to State DOTs, FHWA Offices, NTSB, etc. on Pavement & Concrete Investigations – Identify Rock Types, Minerals, Micro-Cracks & Reaction Products FHWA-TFHRC Aggregates & Petrographic Lab Program Materials Performance in Highways 4/19/2021 14 Alkali Reactive Coarse Aggregates – Siliceous & Carbonate Constituent Effects Open-Graded Aggregate Tested in Geotech Lab Large-Scale Shear- Boxes Aggregate Quality – Cause of Low Concrete Strength in Slip-Form Pavement Coarse Aggregate Polishing in Low Friction Asphalt Pavement Organic Materials in Natural Sand Failing the Organic Colorimetric Test Evaluation of Recycled Concrete Aggregates (RCA) from Urban Rubble Rebar Shadowing in Bridge Deck Placement Over Prestressed/Precast Panels NTSB Investigation of the Hardened Concrete Mixture Properties in Bridge Failure & Investigations of Bus Crashes Involving Asphalt Pavements Blend Aggregate Properties in Stripping Asphalt Mixture Tested in the Lab Example Forensic Petrography and Research Investigations CONTACTS Mr. Richard (Rick) Meininger, PE Federal Lab Manager of the HRDI Aggregates and Petrography Lab (APL) Richard.Meininger@dot.gov Dr. Mengesha Beyene, Ph.D.; Geologist/Petrographer Contract Lab Manager; Petrographic Expert, SES Group and Associates, LLC Mengesha.Beyene.ctr@dot.gov 4/19/2021 15 Questions? Contact info: Michael.Praul@dot.gov 207-512-4917 Image Pixabay 4/19/2021 1 About the Presenter • Georgene M. Geary, PhD, PE is the Principal Engineer and Owner of GGfGA Engineering LLC, a DBE certified consulting firm located near Atlanta, GA. • Georgene’s past experience involved geotechnical, construction, materials, pavements and general transportation research prior to her retirement from Georgia DOT. She is a registered professional engineer in Georgia. • She holds a BS degree in Civil Engineering from the University of Illinois, Champaign-Urbana and a Masters and PhD from Georgia Tech. Her PhD research involved using high-speed 3D laser technology to analyze and predict concrete pavement life. • Beyond consulting she also teaches undergraduates at Georgia Tech as an Adjunct to give back to the next generation. Pavement ME Upgrades Related to Concrete Pavements Georgene M Geary, PhD, PE GGfGA Engineering, LLC NCC Spring Meeting April 13, 2021 4/19/2021 2 The 2021 Pavement ME v2.6 models related to concrete pavement are the same as the 2013 Pavement ME v1.0 -and- the same as the 2004 original MEPDG models THE END Presentation Outline • Highlights of version changes • What (else) has not changed • Inputs (Materials, Climate, Traffic) • SJPCP • Local Calibration & MEPDG Users Group • More change is coming! • Synthesis Report Outline 4/19/2021 3 PMED Version Timeline –Highlights– v2.2 CTE NALS v2.3 NARR SJPCP v1 Same as DARWin-ME v2.6 Current version What hasn’t changed • Drainage is a separate Tool – DRIP 2.0 • Sensitivity analysis capabilities • Concrete models and algorithms for new JPC, CRCP and JPC, CRCP overlays Permeable Base Design Roadway Geometry Base & Subgrade Materials Water flow Edgedrain Design Geotextile/ Separator Layer Design DRIP 2.0 4/19/2021 4 Basic JPCP model • Computes incremental damage in the form of cracking and faulting • Cracking = fatigue failure due to loading, support, environmental conditions • Faulting = loading, loss of load transfer, erodibility of the support, water Figure adapted From NCHRP 1-37A Basic JPCP model - IRI • IRI = combination of: Initial IRI+ Cracking + Faulting + Spalling + Location • Spalling - pavement age, PCC, joint sealant and f-t • Location (Site Factor) – age, FI, subgrade fines Failure can result from: Cracking -or- Faulting -or- IRI 4/19/2021 5 Inputs Materials, Climate, Traffic CTE NARR NALS CTE NARR NALS Materials -- CTE recalibrated in v2.2 • CTE= coefficient of thermal expansion • Concrete property related to movement of concrete due to temperature changes • Tests performed prior to ~2010/2011 commonly used an (incorrect) assumed value for the steel calibration specimen • Important for design: • opening and closing of joints and curling in JPC • crack spacing and crack width in CRCP Stainless steel 4/19/2021 6 CTE effects on Design • Missouri found in their latest local calibration the same design with: • CTE ≤ 5 x 10-6/℉ • no transverse cracking in 30 years • CTE ≥ 6 x 10-6/℉ • >15 percent cracking in just 7.5 years (Titus-Glover et al. 2020) Climate -- NARR and MERRA (future) 1. original .hcd (NCDC- National Climatic Data Center weather stations) 2. NARR = North American Regional Reanalysis (added in v2.2) 3. MERRA = Modern Era Retrospective Reanalysis for Research Applications • The Enhanced Integrated Climate Model (EICM) is a combination of 3 different models • JPCP design uses hourly climate data! • The EICM effects every aspect of JPCP distress prediction • Cracking and Faulting are affected by curling and warping • IRI uses climate in both the Spalling and Site Factor components MERRA data will be incorporated in v3.0 4/19/2021 7 NARR and MERRA2 climate stations in PMED NARR - concrete MERRA2 - asphalt Traffic – NALS • NALS = Normalized Axle Load Spectra (Loads) • Actual loads on the trucks by vehicle class • Loads = f(vehicle class and axle) • NALS added: Global, Heavy, Typical , Light • TTC = Truck Traffic Classifications (Class) • % vehicle by class (i.e. 30% Class 9, 10% Class 10, etc.) • Not Equivalent Single Axle Load (ESAL) 50x heavier! 4/19/2021 8 0 2 4 6 8 10 12 14 16 18 20 0 10,000 20,000 30,000 40,000 50,000 60,000 Pe rc en t o f A xl es Axle load, lbs. Single 1-37A Tandem 1-37A FHWA Vehicle Classes Loads (by axle) SingleTandem Class 9 vehicle Traffic – NALS – Class 9 vehicle Traffic – 4 Default NALS added in v2.2 0 2 4 6 8 10 12 14 16 0 10,000 20,000 30,000 40,000 50,000 60,000 Pe rc en t o f A xl es Axle load, lbs. Tandem 1-37A Tandem LIGHT Tandem HEAVY 4/19/2021 9 From: PMED webinars on me-design.com 9 inch JPCP 8 inch JPCP 4/19/2021 10 SJPCP – added in v2.3 • COA- concrete overlay over asphalt • SJPCP- short jointed plain concrete pavement = type of COA Typically 6’ x 6’ panels Local Calibration Why do we get different results? 4/19/2021 11 From: FHWA AID-PT 2019/2020 Annual Report, FHWA peer Exchange 2019 “WHAT STRUCTURAL PAVEMENT DESIGN METHODOLOGIES ARE AGENCIES CURRENTLY UTILIZING?” Local Calibration issues • 3 Failure modes for JPC: faulting, cracking and IRI • Changes in Materials, Climate and Traffic INPUTS • Complicated program with a multitude of inputs! 4/19/2021 12 Calibration Assistance Tool https://me-design.com/MEDesign/Webinars.html MEPDG Users Group From: MEPDG Users Group Report APT, 2019 4/19/2021 13 Users Group Surveys and discussion 0 2 4 6 8 10 12 14 16 0% 10% 20% 30% 40% 50% 60% 2016 2017 2018 2019 N um be r o f R es po nd en ts Pe rc en t o f R es po nd en ts Year Percent Number Implemented PMED for concrete? Top Issues Year/ # of respondents Top issue (# of respondents choosing) 2nd top issue 3rd top issue 2016/25 Local Calibration (12) Data inputs (8) Performance Data availability (7) 2017/21 Local Calibration (10) Features not in or not calibrated for PMED (5) Performance Data availability (4) HMA inputs (4) 2018/26 Local Calibration (13) Features not in or not calibrated for PMED (8) Data inputs (6) 2019/29 Local Calibration (18) Data inputs (9) Features not in or not calibrated for PMED (7) Performance Data availability (7) 4/19/2021 14 Discussion Items • Widened slabs • Use of AASHTO 93 to limit min or max thicknesses • Faulting model – thicker pavement sometimes worse? • Inputs change sensitivity • Dowel type not addressed • Design Catalogs PMED v3.0 • Web Based • MERRA (latest climate data) for concrete pavements • Enhanced slab interface model (NCHRP 1-51) 4/19/2021 15 ADDITIONAL NEEDS • Improved models to represent faulting, foundations and drainage • Method to measure and incorporate curl and warp (best to not build in stresses in the first place!) • Model longitudinal cracking in JPCP and transverse cracking and faulting in SJPCP Synthesis Document Outline • Introduction • Changes related to concrete pavements by software version • Tools • What (else) has not changed • Materials • Climate • Traffic • Concrete Pavements (Design) • Local Calibration • MEPDG Users Group • Research in Progress • Conclusion 4/19/2021 16 PMED Timeline in the Synthesis v1 v2.2 v2.3 v2.5 v2.5.5 v2.6v2.1 Educational Version v1.5.08 2012 2015 2016 2017 2018 2019 20202014 MapME Added BcT Tool Added RePave and CAT5 added -Recalibrated due to CTE1 -New NALS added2 -PCC overlays modified3 -SJPCP added3 -NARR added4 -Comparator tool added -Preventative maint. added -Same as DARWin-ME Climate UI added4 More Details in Section: 1Materials 2Traffic 3Concrete Pavement 4Climate 5Local Calibration TOOLS: PMED: 2021 DRIP v2.0 DARWin-ME 20132011 v2.5.3 (October 2018) Software Bug fixes Questions? THE REAL END ggeary@ggfga.com www.ggfga.com 1 PAVEMENT RESILIENCE National Concrete Consortium April 13, 2021 Leif G. Wathne, P.E. American Concrete Pavement Association Starting point… Climate change is happening… Frequency and intensity of storms Sea level rise Temperature rise Not discussing causes of climate change About adapting as engineers 2 “Engineers…design...structures…and materials to fulfill functional objectives and requirements while considering the limitations imposed by practicality, regulation, safety and cost.” [BLS September 2006] For pavements, this means designing cost effective solutions to function in the environment and loading regime it is expected to be exposed to during its lifetime… Recall from undergraduate civil engineering curriculum… [Image: Google Images] 3 It all starts with geotechnical engineering… Sample in-place soils Classify (LL, PL etc.). Proctor curve (moisture and MDD) CBR test? Correlation? Soaked…? K-Value Design pavement section [Images: IndiaMart.com] Site work… Work the in-place soils (scarify, dry, wet, etc.) Compact to some percentage of MDD at optimum in required number of lifts… Similar for subbase, base… Place pavement surface (concrete or asphalt) Crown, super, ditches, drainage structures, etc. to direct and keep water away Of course… don’t build in floodplains 4 Fundamental assumption of this process… Pavement layers will REMAIN at or near optimum… system was specifically designed to direct and keep water away. May have been reasonable when road network was developed… but the context has changed, in some cases substantially! Based on what we now know, is continuing to follow this process good engineering practice? Flood Mapping Today… 2017 Homeland Security OIG report: 2/3 of flood maps out of date or inaccurate FEMA’s flood maps look backwards at past events for 100 and 500 year storms FEMA study predicts riverine flood areas increase by 45% by 2099 5 So what…? We’re in the pavement world… [Images:CBO 2019] Carolinas have been hit by TWO 500-year flood events Hurricane Matthew (2016) & Hurricane Florence (2018) I-95 Lumberton, NC (2016) I-95 Lumberton, NC (2016) I-40 Pender County 4-Days post hurricane (2018) With Hurricane Florence, NC had over 2500 road closures 6 HOUSTON (TX) AREA HAS BEEN HIT BY SEVERAL FLOOD EVENTS IN RECENT YEARS – THE WORST WAS HURRICANE HARVEY SEA LEVEL RISE IS ALREADY IMPACTING COASTAL ZONES Sunny sky flooding is becoming a common or daily occurrence SR54 East of Fenwick, DE South Bowers Beach , DE Images: DE Photos courtesy of Jim Pappas, DELDOT, FL Photos courtesy of Amy Wedel, FC&PA Charleston, SC Miami, FL 7 Nebraska DOT reported 1,500 road miles closed FLOODING IN THE PLAIN STATES WAS SEVERE MARCH 2019 Flooding is NOT only a Coastal Issue Iowa I-69 Impacts Flooding is a Primary Risk to U.S. Infrastructure Will likely impact MOST of us! Need to adjust how we design and rehabilitate pavements accordingly 8 Pavement Resilience…? [Icon: Google Images] What Does Resilience Mean in the Pavement Context? FHWA Order 5520 - Transportation System Preparedness and Resilience to Climate Change and Extreme Weather Events (2014) Resilience …is the ability to anticipate, prepare for, and adapt to changing conditions and withstand, respond to, and recover rapidly from disruptions. 9 Rigid and Flexible Pavement Transmit Loads Differently Concrete’s rigidity spreads the load over a large area & keeps pressures on the subgrade low • Load - more concentrated & transferred to the underlying layers • Higher deflection • Subgrade & base strength are important • Requires more layers / greater thickness to protect the subgrade Flexible Pavement Structure Rigid Pavement Structure 7000 lbs load pressure ~ 15 - 20 psi Flexible Base Subbase Subgrade pressure ~ 3 - 7 psi Rigid Subbase Subgrade • Load – Carried by concrete and distributed over a large area • Minor deflection • Low subgrade contact pressure • Subgrade uniformity is more important than strength • Lowered subgrade strength & reduced modulus • Reduced load carrying capacity and >1 year recovery time • Loading accelerates pavement damage / deterioration • Consumes fatigue life faster Reduced pavement life • Maintains high level of strength / stiffness • Subgrade is weak, but still uniform • Spreading of the load means subgrade is not overstressed • Little impact on the serviceability / life Flooding does not impact concrete’s load carrying capacity to the same degree as asphalt’s 7000 lbs load Quantifying the loss of strength after saturation… Soaked vs. Unsoaked CBR Laboratory study Soaking lowers CBR value Loss of strength typically between 20-50% depending on clay and silt content. FDR Results after Saturation Florida field study, US 441 Approx. 40-60% reduction in subgrade modulus (varies) Long recovery time (year(s)) ~3 years loss of pavement life Source: Comparison Between Soaked and Unsoaked CBR, Sathawara Jigar K & Prof. A.K.Patel; International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974 Source: Decision Support Criteria for Flood Inundated Roadways: A Case Study, A. Gundla, Ph.D., E. Offei, Ph.D. G. Wang, Ph.D., P.E. C.Holzschuher, P.E. and B. Choubane, Ph.D., P.E., Presented at the 2020 TRB Annual Mtg 10 Hurricane Florence (2018) Much of the damage can occur during relief and rescue… Hurricane Harvey (2017) [Image: Google Images] … and continue for months! Further exacerbating the pavement damage while weakened [Source: Amy Wedel, FCPA] 11 Making Pavement Resilient to Inundation….? [Image: Google Images] Design Stiffer Pavement Systems… Stiffer Pavements are less impacted by subgrade strength loss and recover faster (stiffer = concrete, cement stabilized bases, increased asphalt thickness) P e rf o rm a n ce Time (years) Rigid System Flexible System Early Rehab Time the road is submerged / not passable 1) Lower drop in performance (Both Short and long term) 2) Quicker opening 3) Shorter recovery time Design Life 4) Less Secondary impacts (less dependence on subgrade / base strength) 12 Modify Design Standards… Stiffen the pavement system and/or make less susceptible to moisture related strength loss Modify soils Stiffen the base Stiffen pavement [Source: RMS 11.050 v3.0 2018] What we learned from Hurricane Katrina Submerged pavement were weaker than ‘dry’ pavement Asphalt pavements Overall strength loss ≈ 2” of new asphalt concrete Damage occurred regardless of the length of time the pavement was submerged Concrete Pavements Little relative loss of strength Resilient modulus(Mr) is similar for ‘dry’ and submerged pavements Impact of Hurricane Katrina on Roadways in the New Orleans Area, Technical Assistance Report No. 07-2TA Kevin Gaspard, Mark Martinez, Zhongjie Zhang, and Zhong Wu; LTRC Pavement Research Group, March 2007 13 [Source: Resilient Pavement Structures in Texas, Andrew Wimsatt, Ph.D., P.E., Texas A&M Transportation Institute and Lisa Lukefahr, P.E., TCPA] Opened roadway shortly after Hurricane Harvey I-610 to I-45 11” CRCP UBOL & 14” CRCP (Const = 1995-2000) Design= 43M ESALS, Carried = 92M ESALS Southmore to Yellowstone 9” CRCP (Const = 1983 & 1984) Design = 7M ESALS, Carried = 22M ESALS Both sections have been flooded at least three times since original construction Houston Experience… pavement opened immediately! Australian Experience is Similar Rigid pavement performs the best at any probability of flooding, and flooding effect is not critical A pavement’s strength may be enhanced by: Strengthening with an overlay Layer Stabilization Converting the road into a rigid or composite pavement through granular layers’ stabilization [Source: Estimating Pavement’s Flood Resilience; Misbah U. Khan, CPEng; Mahmoud Mesbah, Ph.D.; Luis Ferreira, Ph.D.; and David J. Williams, Ph.D.; American Society of Civil Engineer's Journal of Transportation Engineering, Part B Pavements, 2017] “It is settled that a rigid pavement is the more flood-resilient.”(p- 5) 14 What about our existing network…? [Image: Google Images] “Hardening” techniques for existing roadways… (Concrete) Overlays Full Depth Reclamation (FDR) 15 Concrete overlay increases both the height and the structural strength of the roadway 7000 lbs load. 7000 lbs load. pressure ~ 15 - 20 psi Asphalt Base Subbase Subgrade Pressure ~3 - 7 psi at the top of the Asphalt layer Base & subgrade pressures are even lower Concrete Asphalt Base Subbase Subgrade Road Elevation raised the height of the overlay Concrete Overlay as a Resilient Hardening Solution Concrete Overlay Adoption Growing… 0% 2% 4% 6% 8% 10% 12% 14% Prior to 2000 2000-2004 2005-2009 2010-2014 2015-2019 2.0% 2.0% 4.3% 11.3% 12.4% O ve rla ys a s Pe rc en ta ge o f To ta l C on cr et e Pa vi ng , S Y SH-121 Colorado US 69 Oklahoma Concrete overlays included in FHWA’s EDC6 16 Concrete Overlays as an Airfield Resilience Solution Reconstruction and Rehabilitation of Runways at JFK The rehabilitation will provide aircraft a solid concrete runway that is more RESILIENT than asphalt and will increase the useful life of runway by four times” [Source: Port Authority of NY & NJ Press Release, April 2019] Moisture infiltrates base • Through high water table • Capillary action • Causing softening, lower strength, and reduced modulus FDR reduces permeability • Helps keep moisture out • Maintains high level of strength and stiffness even when saturated High water table Un-stabilized Granular Base FDR w/ Cement- Stabilized Base 100 psi 15 psi 100 psi 4 psi FDR as a Resilience Hardening Solution Increases rigidity, reduces permeability, & reduces moisture susceptibility The stabilized base can be topped with either asphalt or CONCRETE surface 17 So… what to do? Where do we start? Can’t address it all… New roadways: Assess inundation potential (updated maps) Design stiffer pavement sections (soils, bases, pavement) Existing roadways: When rehab is needed… assess inundation potential Use resilient hardening solutions (overlay, FDR) Start with evacuation routes, strahnet, NHS… [Image: Google Images] Priority of both Congress and Administration Resilience is prominent in both House and Senate draft bills Biden’s American Jobs Plan “modernize 20,000 miles of highways, roads, and main streets, not only “fixing them first” but “fixing them right,” with safety, resilience, and all users in mind.” Must be ready to respond to their challenge… [Image: Google Images] 18 Fundamentally… Resilience is about good engineering… Recognizing that the service environment of our pavements is changing… Adapting our designs to accommodate Stiffer & and less moisture sensitive structures… Starting with our most critical pavement assets [Image: Google Images] Thanks to Greg Dean and Jim Mack Thank You! www.acpa.org 19 | |
| Understanding the Value of Competition | 👤 Jeremy Gregory 👤 Leif Wathne | Concrete Pavement Technology Tuesday Webinar | 2021 |
| 2021-04-09 | 4/9/2021 1 The Effects of Inter-Industry Competition in the Paving Sector Jeremy Gregory, Omar Swei, Travis Reed Miller, Mehdi Akbarian, Randolph Kirchain Concrete Pavement Technology Center American Concrete Paving Association April 6, 2021 Slide 2 Infrastructure spending is at an all-time low Slide 3 How do we do more with less? Competition among product substitutes could lower prices Substitute: A product or service that satisfies the need of a consumer that another product or service fulfills Slide 4 Inter-industry competition could lower paving prices Does the presence of competition between material substitutes impact pavement material prices? vs 4/9/2021 2 Slide 5 The pavement sector makes for an interesting case study due to the presence of two forms of competition • Intra-Industry Competition: Between firms that pave with the same material • Inter-Industry Competition: Between firms that pave with material substitutes • Focus of this study: Characterize the effect of increased inter-industry competition in the paving sector Slide 6 Intra – industry • Typical indicator – number of bidders for a given job Inter – industry • Number of firms or participants • Market concentration – Department of Justice uses this for monopolies • Market Share How would you measure competition or competitiveness? Slide 7 To characterize the effects of competition in the paving sector we conducted a statistical analysis of 10 years of bids • Oman BidTABS database – Bids, not actual costs • Includes most highway works projects – Some large and PPP projects excluded • We analyze competitive bid data: – Spread out over 10 years (2005-2014) – Across 47 states (excludes HI, NJ, and AK) – 298k pay items, 164k jobs, filtered down to 30,000 data points that are relevant to mainline paving Details on method: Swei et al, 2020 Slide 8 55% 100% • Project size (quantity) • State market size (annual spending) • Price adjustment clauses (asphalt only) • Number of bidders (intra-industry competition) • Dominant market share (% spending on AC; inter-industry competition) 10-Year Average Percent Spending on AC Parameters of interest in Oman BidTabs data 4/9/2021 3 Slide 9 Statistical model shows large impact of inter-industry competition 60 65 70 75 80 Project Size State Market Size Price Adjustment Clause Number of Bidders Dominant Market Share Asphalt Unit-Price ($/ton) 120 140 160 180 200 220 Project Size State Market Size Number of Bidders Dominant Market Share Concrete Unit-Price ($/CY) Intra-industry competition Inter-industry competition Intra-industry competition Inter-industry competition Asphalt only Slide 10 Lower unit-prices for bid items are correlated with increased concrete spending Impact of competition on costs estimated using statistical model Slide 11 Increased competition can translate into more paving 0 500 1,000 1,500 2,000 Current 5% 10% 15% 20% 25% Thousands % S p en t on C on cr e te Annual paving tonnage for a state with a $100M budget Asphalt Tons Concrete Tons 6.5% increase in paving tonnage Assume asphalt price of $65/ton and concrete price of $175/CY Slide 12 Next step: explore mechanism of competition’s impact on prices Understand correlation vs. causation, just like medical studies Correlation between and Smoking Lung Cancer Exercise Mental Health Healthy Diet Life Expectancy What is the mechanism? 4/9/2021 4 Thank you http://cshub.mit.edu/ cshub@mit.edu 4/9/2021 1 Leif G. Wathne, P.E. American Concrete Pavement Association Understanding the Value of Competition [Part 2] “Technology Tuesday” Webinar April 6th, 2021 Passes the gut-check, and verified by the most comprehensive and rigorous scientific analysis ever undertaken on this subject ● Extends the purchasing power of our highway dollar. ● Including asphalt and concrete not only lowers pavement costs, it also improves quality, and spurs innovation. ● Healthy industries can INVEST in training, people and technology MIT: Inter-Industry Competition Lowers Pavement Costs! P So… What’s the Problem? ● Competition is probably the single-most overlooked aspect of getting the most from our pavement investments…!?! ● Most agencies are NOT adequately capitalizing on the benefits of competition between paving industries NOTE: A few states do, and use a healthy two-pavement system to their advantage… Rooted in Self- Reinforcing Analyses • Sole project-by-project focus can cause you to inadvertently miss the bigger opportunity… (i.e. miss the forest for the trees) • Stewardship involves a program of projects… and stepping back allows for a better perspective 4/9/2021 2 Fictional State of Missitucky… • Slowly shifted to a one-pavement system over a few decades • Potential driver: First cost decision-making… • Systematic deselection has essentially led to elimination of concrete pavement lettings and the industry with it… • PTS Process? Based largely on LCCA. “Data Driven”. • Cost inputs for LCCA? No slip form jobs to draw from. Slab replacement? Repair jobs? Ramps? Approach slabs? Such costs are vastly inflated! • No meaningful concrete pavement cost data for LCCA..! • Tried implementing ADAB. Concrete cost inputs still not competitive (LCCA, design, mobilization, equipment, training, supply chain etc.). BUT, asphalt unit bid prices did drop…. for those select few projects. [Image: Google Images] So…. the analysis continues to reinforce decision-making that allows only one industry to flourish! A starving concrete pavement industry is being asked to compete with a mature and dominant asphalt pavement industry that have dozens if not hundreds of projects to bid on year after year…? The pavement costs reflected in this process does not reflect the price Missitucky should be paying… FOR EITHER CONCRETE OR ASPHALT! Lulled into a false sense that they are somehow saving $s Fictional State of Missitucky Of course, this is nothing new… • AASH(T)O knew this over 60 years ago and warned agencies about it in a document written SPECIFICALLY to reinstall faith in the interstate highway program! • Covers a lot of information… including PTS, aiming “to assure the public of full value for their highway dollar.” http://aasho.acpa.org 1960 AAS(T)HO Guide ● In section on cost comparisons (LCCA): “doubt as to the validity [of such analysis] arises in the case where on[e] type of pavement has been given monopoly status by the long-term exclusion of a competitive type.” i.e. cost data is not meaningful ● In section discussing competition, they write “…It is desirable that monopoly situations be avoided, and that improvement in products and methods be encouraged through continued and healthy competition among industries involved in the production of paving materials.” ● Highway officials recognized the importance of establishing and maintaining competing industries. 4/9/2021 3 Having Multiple Bidders on Projects Isn’t Enough… Paving Project Asphalt Contractors • Contractor 1 • Contractor 2 • etc Asphalt Material Suppliers Contractor Competition Limits competition at the supplier level, which can limit effectiveness First Level 2nd Level Paving Project Asphalt Contractors • Contractor 1 • Contractor 2 • etc Asphalt Material Suppliers Concrete Contractors • Contractor 1 • Contractor 2 • Contractor 3 • Contractor 4 • etc Concrete/Cement Material Suppliers Industry Competition Assures competition happens between both contractors and suppliers 3% Impact lowering bid prices 14% Impact lowering bid prices WHAT DOES ALL THIS MEAN? ● Inter-industry competition is foundational to meaningful cost analyses (i.e. LCCA)! ● And by extension… any stewardship program, including ADAB, mix-of-fixes, planning, asset management, etc. [Image: Google Images] Acknowledge that they are a monopsony… and leverage that opportunity! Fundamentally, send a clear signal to both paving industries – serious about marshalling benefits of competition. Programmatic view! Industry will respond (both concrete and asphalt) Must be confident that the state is committed to the health of both industries… involves investment in training, education, equipment, research, etc. All is in the best interest of Missitucky! How to get there…? What can Missitucky do? Several Paths to Spur and Maintain Inter-Industry Competition… Announce letting of a program of concrete projects (as done w/ HMA) • Multiple projects each year over several years signals a sustained commitment • Limits “buying” of jobs… • Can also focus on regions/locations with single bidder lettings • Example: Florida 4/9/2021 4 Another Path to Spur and Maintain Inter-Industry Competition… Maintain healthy industries by balancing quantities (e.g. square yards to tons, $s) • Used successfully be agencies who recognize its in their best interest to have more than one industry • Can smooth the peaks and valleys for each industry to enhance certainty and stability, contributing to consistent competitive pricing and quality • Generates lowest unit prices for both concrete and asphalt pavement • Example: Iowa, Wisconsin… Another Means to Spur and Maintain Inter-Industry competition… Commit to a program of alternate bid projects (ADAB) • Can be effective tool IF done in accordance with FHWA ADAB guidance (T5040.39) and is sustained! • Design equivalence, LCCA bid adjustments no price escalation clauses, equivalent quantity measures, etc. • Example: Pennsylvania, Kentucky, Louisiana, West Virginia… How to get there? ● No single way… but only with two healthy industries will agencies be able to maximize the purchasing power of highway dollars! ● An agency can employ LCCA, ADAB, AM, etc., but will never know what they SHOULD be paying for pavement without inter- industry competition! ● An aging network, growing needs and constrained resources demand a rethinking of how we stretch and steward investment ● Reason why competition is foundational to American way of doing business… it pays dividends! ● Involves a programmatic approach to a healthy two pavement system (i.e. diversify) ● Have to recognize the ‘forest’! ● Must send clear signal to both industries ● NOT about one being better than the other ● Diversify concrete solutions portfolio across all applications (Mix of Fixes) ● Benefit from competition in multiple markets (highways, county roads, streets, airfields) across solutions (minor rehab, major rehab, overlays, reconstruct, new construction) How to get there? 4/9/2021 5 ● Involves a programmatic approach to a healthy two pavement system (i.e. diversify) ● Have to recognize the ‘forest’! ● Must send clear signal to both industries ● Diversify concrete solutions portfolio across all applications (Mix of Fixes) ● Benefit from competition in multiple markets (highways, county roads, streets, airfields) across solutions (minor rehab, major rehab, overlays, reconstruct, new construction) How to get there? C O M P E T I T I O N L C Quality Inno-vationValue C A Planning The value of inter- industry competition is that it enables our stewardship tools like LCCA, ADAB, planning, mix-of- fixes, and asset management to function properly! Understanding the Value… Particularly Important… INFRASTRUCTURE? In the face of massive infrastructure investment. $2 trillion, $3 trillion? Reauth. Must apply lessons learned from the past! Cannot afford public and Congress to lose confidence in program administration “…assure the public of full value for their highway dollar…” “… through continued and healthy competition among industries involved in the production of paving materials.” Ensuring inter-industry competition is a critical component good stewardship! www.acpa.org Questions? Competition Webinar – Questions and Answers The questions submitted during the webinar follow with answers that our speakers have provided. Key resources available include: 1. As a DOT Engineer, can you please share a couple of questions that we could ask our leaders to encourage competition? This is not typically in my scope but I understand its importance. a. What could possibly be the downside to embracing another pavement industry to check and compete with the well-entrenched and dominant asphalt paving industry? b. Why would we not take advantage of ALL the tools available to us to ensure that the taxpayers get the best bang from the highway dollar? c. Is maintaining the status quo the most equitable and cost-efficient approach – given the growing needs, aging roadway network and shrinking resources? 2. Can you share any best practices with AD/AB that enable my DOT to put out projects in this format without doubling the effort? Several colleagues are under the impression that providing design for two systems takes twice as much time. I am certain there are things we can do to address this but don't know where to start. a. FHWA has published a Technical Advisory TA 5040.39 that constitutes best practice for use of ADAB for pavement type selection. It is important to underscore that use of ADAB can be an effective way to make cost-efficient pavement-type selections, provided the process is done in accordance with these FHWA guidelines. Important requirements in those guidelines include; use of equivalent designs (e.g. AASHTOWare pavement ME); use of LCCA bid adjustments; no commodity price adjustments; and use of equivalent materials quantity measures (i.e. SY). b. Several states have used ADAB with some success (e.g. PA, KY, LA, WV), but the process can be contentious at times. Also, regional market dynamics regarding ownership of aggregate sources will impact the effectiveness of ADAB. c. LADOTD published information more than 10 years ago that clearly illustrated that the cost benefits associated with lowered bid prices via ADAB far outweighed the increase design costs associated with producing two pavement designs. Their ROI was 1000 to 1. 3. Can you share with us how you work with senior leaders of DOT's or agencies to help provide understanding to this issue? We see this all the time at the field level, but are pretty certain that a few levels up are not familiar with this issue. Thanks a. The benefits of competition have been shared with DOT leaders in a variety of ways. We have attempted to increase the visibility of this issue at AASHTO via our Alliance for Pavement Competition (www.competitionpaves.org ). Numerous presentation and papers on the issue have been shared at local paving workshops. In select states we have also presented this to senior leadership directly at industry/agency meetings, and in some cases to DOT oversight bodies or even legislators in some cases where local industry so desires. Fundamentally, the message delivered to policy makers is: i. We know from experience that there are no engineering reasons why concrete pavement cannot be part of any agency’s program. ii. We need to take advantage of ALL the tools available to us to ensure that the taxpayers get the best bang from the highway dollar. iii. And we now know from the most scientifically rigorous study ever undertaken on the subject (by the top engineering school in the word) that the introduction of a competing pavement solution in markets where asphalt has a monopoly is an important step toward that end. 4. Great presentation Gentlemen! Who takes the lead on this issue? How do we get FHWA to show leadership and require this work to be done in each state? How do we get AASHTO to counsel their member states on this topic that they agreed upon 60 years ago? a. Terrific question! We are working on both those items as an industry. We initiated a comprehensive federal regulatory and legislative review arguing that existing federal policy in fact requires states to consider alternative combinations of materials. In a complementary effort we helped establish the Alliance for Pavement Competition, an ad-hoc alliance of three associations dedicated to the benefits of inter-industry competition to expand the concrete pavement market. This Alliance participated in AASHTO meetings, in an effort to showcase the benefits of competition and the significant financial opportunities that many agencies are in effect forgoing. The on-going effort has raised the visibility of this issue considerably and brought it into prominent view for federal and state policy makers and lawmakers. It will most certainly require a sustained effort! 5. In my state of Misstucky, how can we get contractors back in the state when they have left? We like to use in state labor/contracting when we can. Part of our issue is that we don't have any instate contractors doing large scale concrete work. a. Fundamentally, Missitucky DOT needs to send a clear signal to industry (both asphalt and concrete) that they are serious about marshaling the benefits of http://www.competitionpaves.org/ competition between industries. Industry needs to be confident that Missitucky is committed to the health of both industries, before they are willing to take the necessary steps (and make the necessary investments) to be competitive. No industry is going to invest resources (equipment, training, education, etc.) unless there is some certainty that the DOT is going to let paving jobs moving forward. 6. With a focus on asphalt vs. concrete, how does competition play out with JRCP vs. CRCP and RCC, etc.? a. Great question. To truly marshal the benefits of interindustry competition you need to leverage competition up the supply chain. Competition between JPCP and CRCP for example only really engages competition at the contractor level. If you bring in HMA, you are no longer just engaging contractors in compietion, but you are also engaging cement and bitumen suppliers in competition. MIT’s research in this arena suggests that contractor-level competition has a 3% impact on lowering bid prices while inter-industry competition has a 14% impact on lowering bid process. Competition Webinar – Questions and Answers | |
| Advancements in Our Knowledge and Action to Control ASR | 👤 Larry Sutter 👤 Patricia Baer 👤 Jim Casilio | Concrete Pavement Technology Tuesday Webinar | 2021 |
| 2021-03-09 | 3/17/2021 1 Guidelines for Identifying and Controlling Alkali Aggregate Reactions Larry Sutter Ph.D., P.E., F.ASTM, F.ACI Materials Science & Engineering Michigan Technological University Background • Alkali-Aggregate Reactivity (AAR) is a common durability issue for concrete transportation structures • Alkali-Silica Reaction (ASR) most common – manifests in 5-15 years • A chemical reaction between alkalis in the pore solution and reactive silica in the aggregate resulting in the formation of an expansive gel and the degradation of the aggregate particle • Map cracking over entire slab area and accompanying expansion-related distresses (joint closure, spalling, blowups). • Mitigation - Use of non-susceptible aggregates, addition of pozzolans to mixture, limiting total alkalis in concrete, minimizing exposure to moisture, addition of lithium compounds Background • Alkali-Aggregate Reactivity (AAR) is a common durability issue for concrete transportation structures • Alkali-Carbonate Reaction (ACR) not very common – manifests in 5-10 years; usually faster than ASR • Expansive reaction between alkalis in pore solution and certain dolomitic limestone aggregates causing dedolomitization and brucite formation • Map cracking over entire slab area and accompanying pressure-related distresses (spalling, blowups), less or no sign of gel. • Cannot be mitigated - avoid use of susceptible aggregates ASR Distress 3/17/2021 2 Stanton’s Bridge (ca. 1930) Alkali-Aggregate Reactivity (AAR) Facts Book. Thomas, M.D.A., Fournier, B., Folliard, K.J. Fort Constitution, Battery Farnsworth, Portsmouth Harbor New Castle, New Hampshire • Fort was built in 1897 using natural cement from Rosendale, New York, excavated coarse aggregate from the outcropping it is built into and local beach sand • Total 7000 yd3 of concrete placed • “Embarrassment” to the CoE due to poor workmanship and “leaking” • Abandoned in 1917 3/17/2021 3 Stanton 1940 • Stanton found the expansion of mortar bars was influenced by: • The alkali content of the cement • The type and amount of the reactive silica in the aggregate • The availability of moisture • Temperature • Other findings • Expansion was negligible when the alkali content of the cement was below 0.60% Na2Oe • Expansion could be reduced by using pozzolans ASR Fundamentals • Required ingredients – All are required • Source of alkalis • Reactive aggregate • Water • Can be mitigated in most cases with SCMs (pozzolans or slag cement) or limiting the alkali loading • Much research has been done to understand ASR • State-of-the-Art knowledge summarized in two available guide documents • Some differences between the two documents but both based on the same research • Summarized in recent MAP Brief https://intrans.iastate.edu/app/uploads/2020/12/MAPbriefWinter2020.pdf Guide Documents 3/17/2021 4 How to Use the Guides? General Principles • Alkali Loading not Alkali Content • Stanton’s research (1940’s research) leads to the concept of ”low alkali cement” which is NOT the important factor • What matters is the total alkali in the concrete or alkali loading (2008 research) • Depends on • Alkali content of cement • Amount of cement • Alkali content of other constituents General Principles • Alkali Loading not Alkali Content wt. % Na2Oeq = (wt. % Na2O) + (0.658 x wt. % K2O) Alkali Loading of Cement lb/yd3 [kg/m3] = Na2Oeq x cement content lb/yd3 [kg/m3] Limit fly ash to 4.0 wt. % Na2Oeq [4.5 wt. % Na2Oeq in AASHTO R 80] General Principles • Two approaches provided in the Guide documents to establish ASR mitigation measures • Performance Requirements • Based on experience • Based on testing • Prescriptive Requirements 3/17/2021 5 Performance Approach Performance Requirements • Determine aggregate reactivity • Field History • ASTM C1260 (AASHTO T 303) • 14-day mortar bar expansion • ASTM C1293 • 1-year concrete prism expansion Performance Requirements • Determine aggregate reactivity • Field History • ASTM C1260 (AASHTO T 303) • 14-day mortar bar expansion • ASTM C1293 • 1-year concrete prism expansion Performance Requirements • Determine aggregate reactivity • Field History • ASTM C1260 (AASHTO T 303) • 14-day mortar bar expansion • ASTM C1293 • 1-year concrete prism expansion 3/17/2021 6 Performance Requirements • Determine aggregate reactivity • Field History • ASTM C1260 (AASHTO T 303) • 14-day mortar bar expansion • ASTM C1293 • 1-year concrete prism expansion Performance Requirements • Determine aggregate reactivity • Field History • ASTM C1260 (AASHTO T 303) • 14-day mortar bar expansion • ASTM C1293 • 1-year concrete prism expansion Performance Requirements • Determine aggregate reactivity • Field History • ASTM C1260 (AASHTO T 303) • 14-day mortar bar expansion • ASTM C1293 • 1-year concrete prism expansion Performance Requirements • Determine aggregate reactivity • Field History • ASTM C1260 (AASHTO T 303) • 14-day mortar bar expansion • ASTM C1293 • 1-year concrete prism expansion 3/17/2021 7 Performance Requirements • Establish the correlation between ASTM C1260 (AASHTO T 303) and ASTM C1293 for any aggregate source before relying on ASTM C1260 (AASHTO T 303) alone or using ASTM C1567 Performance Requirements • Select Preventative Measures • Replace cement with SCMs in varying amounts • ASTM C1567 • 14-day mortar bar expansion [≤0.10% @ 14 days] • Requires correlation between ASTM C1260 [AASHTO T 303] and ASTM C1293 • ASTM C1293 • 2-year concrete prism expansion [≤0.04% @ 2 years] Prescriptive Approach Prescriptive Requirements • Determine aggregate reactivity (R0 – R3) • Determine the Level of ASR Risk (Level 1 – 6) • Determine Structure Class (SC1 – SC4) • Determine Level of Prevention (V – ZZ) 3/17/2021 8 Prescriptive Requirements • Determine aggregate reactivity (R0 – R3) • Determine the Level of ASR Risk (Level 1 – 6) • Determine Structure Class (SC1 – SC4) • Determine Level of Prevention (V – ZZ) Prescriptive Requirements • Determine aggregate reactivity (R0 – R3) • Determine the Level of ASR Risk (Level 1 – 6) • Determine Structure Class (SC1 – SC4) • Determine Level of Prevention (V – ZZ) Prescriptive Requirements • Determine aggregate reactivity (R0 – R3) • Determine the Level of ASR Risk (Level 1 – 6) • Determine Structure Class (SC1 – SC4) • Determine Level of Prevention (V – ZZ) Prescriptive Requirements • Determine aggregate reactivity (R0 – R3) • Determine the Level of ASR Risk (Level 1 – 6) • Determine Structure Class (SC1 – SC4) • Determine Level of Prevention (V – ZZ) 3/17/2021 9 Prescriptive Requirements • Select Preventative Measures • Based on Alkali Loading • Based on use of SCMs Prescriptive Requirements • Select Preventative Measures • Based on Alkali Loading • Based on use of SCMs Prescriptive Requirements • Select Preventative Measures • Based on Alkali Loading • Based on use of SCMs Summary • Key Point: Alkali loading vs. alkali content • Two approaches to prevention • Performance • Prescriptive • All cases – need to know the aggregate reactivity • Use tests as they were designed – modifications skew results • Preventative measures include avoiding the aggregate but when not practicable, limit the alkali loading, use SCMs, or both • Cannot test for the effect of limiting alkali loading 3/17/2021 10 Questions at the End of the Webinar or Feel free to contact me llsutter@mtu.edu 3/17/2021 1 PennDOT: Implementing AASHTO R 80 P A T R I C I A B A E R P E N N D O T B U R E A U O F P R O J E C T D E L I V E R Y C O N S T R U C T I O N A N D M A T E R I A L S D I V I S I O N History: In 1990, cores were taken from I-84. ◦ The pavement was 12 years old and exhibited cracking and centerline deterioration. ◦ Earliest discovery of ASR on a Department owned pavement. In 1991 Department tested several aggregates Results showed a potential for highly reactive aggregates A testing program was discussed with the aggregate industry Started testing all aggregates in 1992 Tested aggregate using AASHTO T 303 Results: 464 aggregates – 75% had expansion test results over 0.10% linear expansion Background of situation that prompted the recent change: Significant ASR deterioration identified in pavement structures ◦ Districts 4, 6 and 8 (to date) ◦ Mix designs contained aggregates which were not identified as ‘reactive’, concrete placed after 1992. ◦ One Example (AASHTO T-303 expansion values) ◦ FA Type A: 0.08% ◦ CA #57: 0.01% ◦ Other Districts have reported preventive maintenance; overlays on concrete pavements less than 10 years old where distress likely was attributable to ASR however no forensic investigation was performed prior to repair and reconstruction. What we did: Who’s been involved in the process – Pro-team Short Term solution – Standard Special Provision Long Term solution ◦ AASHTO R 80 ◦ Review of the prescriptive approach ◦ Basis for future specification developments 3/17/2021 2 Pro-team Pro-team developed ◦ September 5th, 2013 ‘kick off meeting’ Industry (PACA – ACPA – CABA/PPA) ◦ PennDOT Central Office, BOMO and District staff ◦ FHWA ◦ Lead ASR researchers made available ◦ Dr. Michael Thomas – Univ. of New Brunswick participated in the first meeting ◦ Dr. Rogers – University Lavalle, Quebec – ASTM C-1293 evaluation assistance for 3rd party testing using Spratt aggregate Stop Gap Measure - What was considered? Risk of continuing with our current aggregate testing and ASR remediation is considered too high ◦ Need to protect future assets! Most of our aggregates are already considered reactive and when used, remediation required. Inability to identify aggregates solely via petrographic examination as ‘reactive’ or ‘non-reactive’ Impacts to industry (SCM availability) Decision – Mitigate all mixtures Consider all aggregates as reactive until the latest research and remediation strategies can be implemented ◦ Stop Gap Measure ◦ Will require more SCM’s for use by industry ◦ Survey conducted of flyash and GGBFS producers ◦ Industry indicated they have sufficient SCM’s available for this interim measure. This was short term while all aggregate sources were tested. Aggregate Evaluation Letter drafted for Type A aggregate sources Will allow for their choice of four independent labs ◦ National Ready Mix Concrete Association ◦ Concrete Testing Laboratory ◦ American Engineering Technology ◦ Bowser-Morner Coordination with independent labs to make sure everyone was testing the same. Provided guidance on sample sizes, coordination with District and sample custody Sources advised that failure to perform testing would result in loss of use in cement concrete when further specification revisions made 3/17/2021 3 Aggregate Evaluation(continued) Conduct concrete prism testing (ASTM C1293) on aggregates. ◦ Industry and PennDOT to perform testing initially on aggregate sources with T-303 expansions less than or equal to 0.15% a first phase of implementation. ◦ The rest of the sources were tested the following year. The Department purchased a warm room to begin evaluation of aggregates. We took random samples of aggregates sent to the private labs to conduct in house evaluations also. The testing went well with the independent labs. AASHTO R 80: Protocol for Alkali Aggregate Reactivity ◦ ASR and ACR ◦ Selecting preventive measures for ASR reactive aggregates ◦ Two approaches for ASR prevention: ◦ Prescriptive approach – Involves a number of factors and decision-based methods. This was used for our specification. ◦ Performance approach – Based on laboratory testing of the aggregates, SCM’s or lithium nitrates used to determine the amount required to control deleterious expansion. ◦ Involves a 2-year duration concrete prism test ◦ Several sources have opted to do this after getting their initial test results (ASTM C 1293) ◦ Looking at field performance as possible approach to how an aggregate performs PennDOT Specification: All fine and coarse aggregates for use in concrete were tested according to ASTM C 1293 New sources that want to be used in concrete will be tested according to AASHTO T 303 and ASTM C 1293. ◦ The Department has purchased an additional warm rooms. We have the capacity to test 100 samples. ◦ The AASHTO T 303 test result will be used for mitigation requirements until the ASTM C 1293 is finished ◦ Any new source with an expansion that indicates the aggregate is non-reactive (R0) will initially be listed with an expansion of 0.11% (R1) requiring ASR mitigation until ASTM C 1293 is completed. A source may opt to do mixture qualification to determine the amount of pozzolan, metakaolin or lithium needed to mitigate. ◦ This is a two year test (ASTM C 1293). ◦ If the expansion of the concrete prism is less than 0.04% after two years, the preventive measure will be deemed effective with the reactive aggregate(s) PennDOT Specification: Prescriptive Approach: The Pro-Team made some minor changes to the tables in R 80 1. Classification of Aggregate Reactivity : Aggregate Reactivity Class Description of Aggregate Reactivity 1-Year Expansion in ASTM C-1293 (percent) 14-d Expansion in AASHTO T-303 (percent) R0 Non-reactive ≤ 0.04 ≤ 0.10 R1 Moderately reactive >0.04, ≤ 0.12 >0.10, ≤ 0.30 R2 Highly Reactive >0.12, ≤0.24 >0.30, ≤0.45 R3 Very Highly Reactive >0.24 >0.45 3/17/2021 4 PennDOT Specification: 2. Level of ASR Risk: PennDOT Specification Level of ASR Risk: R 80 R0 R1 R2 R3 Risk Level 1 Risk Level 2 Risk Level 3 Risk Level 4 PennDOT Specification: 3. Determining the Level of Prevention: PennDOT Specification Classification of Structure Determining the Level of Prevention: R 80 Level of ASR Risk S1 S2 S3 Risk Level 1 V V V Risk Level 2 V W X Risk Level 3 W X Y Risk Level 4 X Y Z PennDOT Specification: 4. Structure Classification: R 80 PennDOT Specification: 4. Structure classification: PennDOT Specification Structure Class Consequences Acceptability of ASR Structure/Asset type Publication 408 Sections S1 Safety and future maintenance consequences small or negligible Some deterioration from ASR may be tolerated Temporary structures. Inside buildings. Structures or assets that will never be exposed to water 627, 620, 621, 624, 627, 628 643, 644, 859, 874, 930, 932, 934, 952, 953, 1005 S2 Some minor safety, future maintenance consequences if major deterioration were to occur Moderate risk of ASR acceptable Sidewalks, curbs and gutters, inlet tops, concrete barrier and parapet. Typically structures with service lives of less than 40 years 303, 501, 505, 506, 516, 518, 523, 524, 525, 528, 540, 545, 605,607, 615, 618, 622, 623, 630, 633, 640, 641, 658, 667, 673, 674, 675, 676, 678, 714, 875, 852, 875, 910, 948, 951, 1025, 1001, 1040, 1042, 1043, 1086, 1201, 1210, 1230, Miscellaneous Precast Concrete S3 Significant safety and future maintenance or replacement consequences if major deterioration were to occur Minimal risk of ASR acceptable All other structures. Service lives of 40 to 75 years anticipated. 530, 1001, 1006, 1031, 1032, 1040, 1080, 1085, 1107, MSE walls, Concrete Bridge components and Arch Structures 3/17/2021 5 PennDOT Specification: 5. Minimum Levels of Supplementary Cementitious Materials: PennDOT Specification Table G: Type of SCM (1) Alkali Level of SCM (%Na2Oe) (2) (3) Level V (4) Level W Level X Level Y Level Z (5) (11) Class F or C flyash (6) ≤ 3.0 - 15 20 25 35 Class F or C flyash (6) >3.0, ≤ 4.5 - 20 25 30 40 GGBFS ≤ 1.0 - 25 35 50 65 Silica Fume (7) (8) (9) (10) ≤ 1.0 - 1.2 LBA 1.5 x LBA 1.8 x LBA 2.4 x LBA PennDOT Specification: Example #1 – using draft specification Step #1: Using a coarse aggregate with a reactivity of 0.18% and a fine aggregate with a reactivity of 0.03% ◦ According to Table C: ◦ The coarse aggregate is a R2 reactivity class. ◦ The fine aggregate is non reactive or R0. ◦ For mix designs use the highest reactivity level of any aggregates used. Aggregate Reactivity Class Description of Aggregate Reactivity 1-Year Expansion in ASTM C-1293 (percent) 14-d Expansion in AASHTO T-303 (percent) R0 Non-reactive ≤ 0.04 ≤ 0.10 R1 Moderately reactive >0.04, ≤ 0.12 >0.10, ≤ 0.30 R2 Highly Reactive >0.12, ≤0.24 >0.30, ≤0.45 R3 Very Highly Reactive >0.24 >0.45 Example #1 continued Step #2: The next step is to figure out the level of ASR risk ◦ According to Table D: Aggregate Reactivity Class ◦ This aggregate would be at a Risk Level 3 R0 R1 R2 R3 Risk Level 1 Risk Level 2 Risk Level 3 Risk Level 4 3/17/2021 6 Example #1 continued Step #3: Determine Level of prevention. The structure classification needs to be know in order to determine the level of prevention. ◦ See Table F: If this mix design was for concrete paving under section 506, then the structure class would be S2. If this mix design was for LLCP- long life concrete pavement under section 530, then the structure class would be S3. Structure Class Consequences Acceptability of ASR Structure/Asset type Publication 408 Sections S1 Safety and future maintenance consequences small or negligible Some deterioration from ASR may be tolerated Temporary structures. Inside buildings. Structures or assets that will never be exposed to water 627, 620, 621, 624, 627, 628 643, 644, 859, 874, 930, 932, 934, 952, 953, 1005 S2 Some minor safety, future maintenance consequences if major deterioration were to occur Moderate risk of ASR acceptable Sidewalks, curbs and gutters, inlet tops, concrete barrier and parapet. Typically structures with service lives of less than 40 years 303, 501, 505, 506, 516, 518, 523, 524, 525, 528, 540, 545, 605,607, 615, 618, 622, 623, 630, 633, 640, 641, 658, 667, 673, 674, 675, 676, 678, 714, 875, 852, 875, 910, 948, 951, 1025, 1001, 1040, 1042, 1043, 1086, 1201, 1210, 1230, Miscellaneous Precast Concrete S3 Significant safety and future maintenance or replacement consequences if major deterioration were to occur Minimal risk of ASR acceptable All other structures. Service lives of 40 to 75 years anticipated. 530, 1001, 1006, 1031, 1032, 1040, 1080, 1085, 1107, MSE walls, Concrete Bridge components and Arch Structures Example #1 continued Step #4: Let’s say the design is for concrete pavement (RPS – section 506) ◦ The Structure Classification would be S2 ◦ From Table E – Determining the level of prevention Classification of Structure ◦ With a Risk Level of 3 and a S2 classification, this mix needs a prevention level X Level of ASR Risk S1 S2 S3 Risk Level 1 V V V Risk Level 2 V W X Risk Level 3 W X Y Risk Level 4 X Y Z Example #1 continued Step #5: ◦ Let’s say we are going to pozzolan to mitigate for ASR. ◦ See Table G for the minimum replacement levels ◦ The mix needs a Level X replacement so the pozzolan replacement levels would be: ◦ 20% for a Class F or C flyash with an alkali level of 3.0% or less ◦ 25% for a Class F or C flyash with an alkali level greater than 3.0% or less than or equal to 4.5% ◦ 35% for GGBFS ◦ 1.5 x LBA for Silica Fume but not less than 7% Type of SCM (1) Alkali Level of SCM (% Na2Oe) (2) (3) Level V (4) Level W Level X Level Y Level Z (5) (11) Class F or C flyash (6) ≤ 3.0 - 15 20 25 35 Class F or C flyash (6) >3.0, ≤ 4.5 - 20 25 30 40 GGBFS ≤ 1.0 - 25 35 50 65 Silica Fume (7) (8) (9) (10) ≤ 1.0 - 1.2 LBA 1.5 x LBA 1.8 x LBA 2.4 x LBA Example #2 – using draft specification Step #1: Using a coarse aggregate with a reactivity of 0.10% and fine aggregate with a reactivity of 0.06% ◦ According to Table C: ◦ Both aggregates are a R1 reactivity class. Aggregate Reactivity Class Description of Aggregate Reactivity 1-Year Expansion in ASTM C-1293 (percent) 14-d Expansion in AASHTO T-303 (percent) R0 Non-reactive ≤ 0.04 ≤ 0.10 R1 Moderately reactive >0.04, ≤ 0.12 >0.10, ≤ 0.30 R2 Highly Reactive >0.12, ≤0.24 >0.30, ≤0.45 R3 Very Highly Reactive >0.24 >0.45 3/17/2021 7 Example #2 continued Step #2: The next step is to figure out the level of ASR risk ◦ According to Table D: Aggregate Reactivity Class ◦ This aggregate would be at a Risk Level 2 R0 R1 R2 R3 Risk Level 1 Risk Level 2 Risk Level 3 Risk Level 4 Example #2 continued Step #3: Determine Level of prevention. The structure classification needs to be know in order to determine the level of prevention. ◦ See Table F: If this mix design was for concrete paving under section 506, then the structure class would be S2. If this mix design was for LLCP- long life concrete pavement under section 530, then the structure class would be S3. Structure Class Consequences Acceptability of ASR Structure/Asset type Publication 408 Sections S1 Safety and future maintenance consequences small or negligible Some deterioration from ASR may be tolerated Temporary structures. Inside buildings. Structures or assets that will never be exposed to water 627, 620, 621, 624, 627, 628 643, 644, 859, 874, 930, 932, 934, 952, 953, 1005 S2 Some minor safety, future maintenance consequences if major deterioration were to occur Moderate risk of ASR acceptable Sidewalks, curbs and gutters, inlet tops, concrete barrier and parapet. Typically structures with service lives of less than 40 years 303, 501, 505, 506, 516, 518, 523, 524, 525, 528, 540, 545, 605,607, 615, 618, 622, 623, 630, 633, 640, 641, 658, 667, 673, 674, 675, 676, 678, 714, 875, 852, 875, 910, 948, 951, 1025, 1001, 1040, 1042, 1043, 1086, 1201, 1210, 1230, Miscellaneous Precast Concrete S3 Significant safety and future maintenance or replacement consequences if major deterioration were to occur Minimal risk of ASR acceptable All other structures. Service lives of 40 to 75 years anticipated. 530, 1001, 1006, 1031, 1032, 1040, 1080, 1085, 1107, MSE walls, Concrete Bridge components and Arch Structures Example #2 continued Step #4: Let’s say the design is for long life concrete pavement (section 530) ◦ The Structure Classification would be S ◦ From Table E – Determining the level of prevention Classification of Structure ◦ With a Risk Level of 2 and a S3 classification, this mix needs a prevention level X Level of ASR Risk S1 S2 S3 Risk Level 1 V V V Risk Level 2 V W X Risk Level 3 W X Y Risk Level 4 X Y Z Example #2 continued Step #5: ◦ Let’s say we are going to use a pozzolan to mitigate for ASR. ◦ See Table G for the minimum replacement levels ◦ The mix needs a Level X replacement so the pozzolan replacement levels would be: ◦ 20% for a Class F or C flyash with an alkali level of 3.0% or less ◦ 25% for a Class F or C flyash with an alkali level greater than 3.0% or less than or equal to 4.5% ◦ 35% for GGBFS ◦ 1.5 x LBA for Silica Fume but not less than 7% Type of SCM (1) Alkali Level of SCM (% Na2Oe) (2) (3) Level V (4) Level W Level X Level Y Level Z (5) (11) Class F or C flyash (6) ≤ 3.0 - 15 20 25 35 Class F or C flyash (6) >3.0, ≤ 4.5 - 20 25 30 40 GGBFS ≤ 1.0 - 25 35 50 65 Silica Fume (7) (8) (9) (10) ≤ 1.0 - 1.2 LBA 1.5 x LBA 1.8 x LBA 2.4 x LBA 3/17/2021 8 ASTM C 1293 Results as of August 2017: Currently, 36% of our aggregates are reactive compared to 75% prior to starting the ASTM C 1293 testing Reactivity Level Number of Aggregates R0 240 R1 99 R2 33 R3 2 Issues: Pilot projects were implemented on sidewalks and sections of pavement. ◦ Mitigations levels of X, Y and Z were placed (using flyash and slag cement) ◦ No noticeable differences on the pavement ◦ Premature wearing of the hand finished sidewalks were noticed ◦ Issues noticed on some sidewalks not involved with the pilot projects ◦ Investigation determined that it was a lack of proper curing ◦ Department is making some changes to address this issue ◦ Classify sidewalks as S1 instead of S2 in our specification ◦ Program to certify concrete finishers and train construction inspection staff ◦ Sidewalk specification is being drafted Next Steps: Developed a five year cycle for testing Currently in the first year of the next cycle of testing Department and Industry are still evaluating and looking at new test methods that are being developed. Continue Review of on-going research (mini-concrete prism test, alternate SCM’s etc.). Identify additional ASR affected assets and document using AASHTO ASR inventory tool. Contact Information: Patricia Baer ◦ PennDOT Materials and Testing Lab ◦ Email: patrbaer@pa.gov www.pacaweb.org www.specifyconcrete.org Initial Industry Concerns Aggregate and Concrete Producers of PA An Increase in levels of mitigation would bring: An Increase in Scaling Strength Gain Issues Reduction in Aggregate Availability PennDOT / Industry Proteam www.pacaweb.org www.specifyconcrete.org Pennsylvania geology www.pacaweb.org www.specifyconcrete.org We are a Limestone State www.pacaweb.org www.specifyconcrete.org PA Results C1293 vs C1260 www.pacaweb.org www.specifyconcrete.org We are a Limestone State www.pacaweb.org www.specifyconcrete.org SR 119 South of Greensburg ASR Workplan Two Projects Rich Jucha, P.E. ACPA-PA SR 662 Fleetwood www.pacaweb.org www.specifyconcrete.org Three Levels of Mitigation SCM Level W Level X Level Z Class F Flyash 15% 25% 35% Slag Cement 25% 50% 65% www.pacaweb.org www.specifyconcrete.org Strength Gains / Sidewalk Scaling www.pacaweb.org www.specifyconcrete.org Scaling A great quote: This is not a finisher problem. This is not a producer problem. This is not a specifier problem. This is an industry problem! www.pacaweb.org www.specifyconcrete.org Reducing Scaling of Concrete Surfaces A STIC Initiative State Transportation Innovation Council Construction and Materials TAG 1. Finisher certification: ACI Flat Work Finisher or NRMCA exterior concrete finisher 2. A Training Module for Construction Insp. (Concrete QIC working on a sidewalk specification) www.pacaweb.org www.specifyconcrete.org Finisher certification: ACI Flat Work Finisher or NRMCA exterior concrete finisher Clearance Transmittal Issued Into effect April 2022 www.pacaweb.org www.specifyconcrete.org Not just a concern on sidewalks www.pacaweb.org www.specifyconcrete.org What we gained and learned We now mitigate smarter Aggregate Availability New cost of mitigation Reduced side effects (scaling & strength gain) Mix design preparation and approval It is not that hard !! Get everyone at the table from the beginning www.pacaweb.org www.specifyconcrete.org Education is the Key ! Aggregate and Concrete Producers Mix Design Aggregate Classification What does it mean Mix design approval Specification revision Assign proper service life Adjust Acceptance time 56 days Training and Expectations of Field Inspection Personnel www.pacaweb.org www.specifyconcrete.org Education is the Key! Construction Personnel: Get the information to those who need it. The Finishers Critical need for curing to produce durable concrete Strength Gain Expectations www.pacaweb.org www.specifyconcrete.org Limitations and Expectations For Pennsylvania AASHTO R80 provided a timely improvement C1293 provided us benefits over C1260 but it is limited!! Our current test methods do not match most expectations ASTM C1260 ASTM C1293 Long Term Exposure Blocks www.pacaweb.org www.specifyconcrete.org Keep all at the table while ASR Knowledge Continues to Advance Use of Field History R80 and C1778 Advantages for Producers Bridge the disconnect A more complete understanding of their material Advantage for Specifiers /Owners Reduce the cost of over mitigation in $ and side effects Improved Aggregate Availability www.pacaweb.org www.specifyconcrete.org Keep all at the table while ASR Knowledge Continues to Advance Research on New Test Methods and Materials FHWA T-Fast Method Terry Arnold, FHWA Accelerated Concrete Cylinder Test Anol Mukhopadhyay, Texas Transportation Institute April 2021 ASSHTO Publication Alternative Concrete Pozzolans for Transportation Infrastructure Farshad Rajabipour, Penn State www.pacaweb.org www.specifyconcrete.org We will be glad to help Dr. Lawrence Sutter, Ph.D., P.E. Michigan Technology University llsutter@mtu.edu Patricia Baer Pennsylvania Department of Transportation patrbaer@pa.gov James Casilio, P.E. Pennsylvania Aggregates and Concrete Association jimc@pacaweb.org Binder1.pdf slides-pt 2 slides pt 3 | |
| Portland Cement Concrete PCC Paving Inspection | 👤 John Hart 👤 Jerod Gross | Concrete Lunch & Learn | Winter 2020–2021 |
| 2021-03-09 | PCC Paving Inspection March 5, 2021 John M. Hart PCC Field Engineer Bureau of Construction and Materials – Iowa DOT Jerod Gross Senior Project Manager Snyder & Associates, Inc. Topics • Traffic Control and Safety • Plant • Grade (through curing) • Protection • Sawing & Sealing • Closeout Traffic Control • Drive the work zone in day and night • Review skids, complaints, crashes • Communicate deficiencies to Contractor/Inspector (ongoing) • Be timely in repairs and adjustments • Document Safety • Proper gear for visibility • Leave yourself an out • Be aware of backing vehicles • Don’t assume operators see you • Don’t walk under spreader belt • Trip hazards (string line, dowel baskets, grade) • Limit haul road dust • Be aware of project and user traffic Safety • Safely sample • Check in • Be aware of flow • Acknowledgement with operators • Follow rules of Contractor • Production vehicles have ROW Plant • Loader operator critical to consistency • Minimize segregation • Avoid high cone shapes • Work different areas • Uniform moisture • Stable drainable base • Draw from areas of known moisture • Limit contamination • Mud on tires • Digging into base • Comingle Aggregate Stockpiles Plant Mixing • Impact • Uniformity • Air content • Central plant • Minimum 60 seconds • Do not exceed rated capacity • Ready mix • Do not exceed rated capacity • Certified in working order • 60 to 90 revolutions Iowa DOT: 2001.21 SUDAS: 7010 3.01 Iowa DOT 2301.03, E, PV-101 SUDAS Sect. 7010 3.02, E Grade Dowel Baskets • Correct number and placement of pins • Up to 3 tie wires may remain uncut • Proper coating and no damage Grade Dowel Baskets • Inspect level and alignment across joint • Sight down grade • Locate joint for sawing • Adjust as needed to match side roads, cross-overs, etc… • Proper alignment ensures working joint Grade Subgrade/base • Wet when dry • Pay special attention when hot, low humidity, and windy • Do not over wet after rain Iowa DOT 2109.03 SUDAS 7010 3.02 B Grade Delivery • Proper time (minutes) • Dump - 30 without retarder • Dump - 60 with retarder • Ready mix - 90 • Continuous mixing • Reasonably close to paver • Continuous steady supply • Ensure dumps are getting cleaned out • Consider retarder Iowa DOT: 2301.02, D, & 2001.21 SUDAS: 1.05 & 3.01, A Grade Additions • Ready mix only • Mix at least 30 revolutions • Ensure total water does not exceed maximum water Iowa DOT: Articles 2301.02 C SUDAS: 7010 3.01 A Grade Testing - Slump • Iowa DOT • Not required on slip form • Non slip form ½” to 4 inch • SUDAS • ½” to 2 ½” machine finish • ½” to 4 “ hand finish • Minimum frequencies • Non-complying test • Clearly communicate results • If possible stop incorporating • Pull ready mix truck off and spin • Test each truck until complying Iowa DOT: 2301.02 B, IM 204, IM 317 SUDAS: 7010 2.02 B, Table 7010.02, IM 317 Grade Testing – Air Content • Calibrate, correlate, and have backup air meters • Minimum frequencies • Iowa DOT and SUDAS • Acceptance is prior to consolidation • 8.0% +/- 2% slip form • 7.0% +/- 1.5% non slip form Iowa DOT: 2301.02 B, IM 204, IM 318 SUDAS: 7010 2.02 B 2, Table 7010.02, IM 318 Target Anticipated Loss Grade Testing – Air Content • Intent is to have 6.0% after consolidation • Loss should be checked • Once per day 1st 3 days • Once per week thereafter • Communicate with finishers • Engineer may adjust loss • Contractor should work towards target when < 7.0% or > 9.0% Iowa DOT: 2301.02 B, CM 9.63 SUDAS: 7010 2.02 B 2 P av er Non‐ complying verification test Test immediately behind paver, air is between 5% and 8% Last verification test Non‐complying concrete limits Test every load in front of paver until two consecutive complying tests Each load is tested and evaluated for compliance Do not incorporate loads below the lower target by more than 0.5% or above the upper target by more than 1.0% P av er Non‐ complying verification test Test immediately behind paver, air is between 5% and 8% Last verification Non‐complying concrete limits Test every load in front of paver until two consecutive complying tests Each load is tested and evaluated for compliance Do not incorporate loads below the lower target by more than 0.5% or above the upper target by more than 1.0% Non‐complying concrete limits When verification test is more than 0.5% above or below the target, coring may be considered Test immediately behind paver, air is below 5% or above 8% Grade Placement • Close to paver • Avoid damaging or contaminating subgrade/base • Maintain constant supply and head for best smoothness • Belt placer and spreader aid in providing consistent head of concrete • Pile from a belt placer should be bell-curved • Segregation may be occurring if the pile is skewed Grade Consolidation • Avoid excessive vibration • Frequency should match mix workability and paver speed in range of 4,000 to 8,000 VPMs • Monitor vibration • Twice per day manually • Electronically for DOT projects over 50,000 yds^2 Iowa DOT: 2301.03, A, CM 9.64, IM 384 SUDAS: 7010 3.01, B Grade Finishing • Remove some imperfections but avoid over finishing • Do not “bless the slab” when finishing • Check smoothness with straight edge • Avoid over wetting burlap • Excessive surface paste indicates • To much water • Over vibration • Excessive finishing Iowa DOT: 2301.03, A, & H, CM 9.14 & 9.41 SUDAS: 7010 3.02, H Grade Dimensional Checks • Periodically check • Pavement width • Edge slump • ½” or less when no abutting pavement • ¼” or less when abutting pavement • Cross-slope prior to finishing • Thickness - observe contractor probing • Immediately communicate issues Iowa DOT: 2301.03, A & H, CM 9.44 & 9.53 SUDAS: 7010 3.07.D Grade Tie Bars • Depth should be approximately T/2 • Reasonably level • Perpendicular joint tying • Approximately 18 inches from transverse joint • Visual for construction joints • NDT or probing during construction for contraction joints Grade Micro Texture • Adequate contact area • Burlap drag produces better texture and smoothness with lower noise levels • Made moist not drenching constantly • Keep clean Iowa DOT: 2301.03 H, CM 9.42 SUDAS: 7010 3.02, H 5 Grade Macro Texture • Longitudinal or transverse depending on application • Shallow less noise than deep • Adjust tine angle and length for desired depth (keep consistent) • Minimize positive texture by keeping tines straight and clean • Don’t stop the tine rake in down position • Some hand work areas can be excluded Grade SUDAS Microtexture: Turf or Burlap Drag Macrotexture: (when specified) Iowa DOT Microtexture: Turf or Burlap Drag Macrotexture when speed limit is greater than 35 mph. (Table 2301.03-1) Grade Curing • Material meets specification and lot number • Well agitated • Apply as close to paver as possible but no more than 30 minutes after finishing • Even and complete coverage “white paper” • Adjust for wind • Edge covered as well • Application rate of at least 0.067 gal per yd^2 Iowa DOT: 2301.03 K, 4105 SUDAS: 7010 3.02 I Cold Weather Protection • Burlap cover can accelerate curing process or protect during cold weather • Monitor forecast temperature to determine if protection is necessary Protection: SUDAS & Iowa DOT : DOT Table 2301.03- 2 Min. temp needed to start: 34ºF and rising Temp for stopping: 38ºF or less and falling Min. mix temp: 40ºF Hot Weather Protection • If rate of evaporation is 0.3 psf per hour or greater, discontinue placement of concrete. • ACPA Evaporation Rate Calculator • HIPERPAV Rain Damage 29 Cover it and leave alone Do not finish rain water into the surface Diamond grind to re-establish texture SUDAS – discretion of Engineer Iowa DOT - 3 levels of rain damage Rain Damage – Iowa DOT 30 Case 1 Case 2 Case 3 Texture is absent from practically all of surface area. Surface appearance may have a "sandy" appearance or may be "pock" marked from the rain droplets. An occasional edge repair may be required due to excess edge slump or from edge rounding. Small areas along edge may have coarser particles of fine aggregate exposed. Surfaces finished in the rain or after a rain are also included in Case I. This includes any manipulation of the pavement surface including mopping of the surface to attempt to remove rainwater or retexturing while rainwater is present. Surface mortar has been practically all removed to an extent that coarse particles of the coarse aggregate fraction are visible. Considerable erosion of edges has occurred, but not to an extent that pavement width is affected. Intermittent edge repair may be required as well as some surface patching of slight troughs or depressions that may have formed in pavement surface due to flowing water. Texture is totally absent from the surface and cement mortar has been eroded to an extent that coarser particles of the fine aggregate fraction are generally exposed. Some slight troughs or depressions are apparent, exposing coarse aggregate particles, but this damage is confined to a limited area or randomly spread intermittently throughout damaged area. Some edge repairs may be required to restore eroded edges. Surface mortar that was removed by rain water, but later replaced or supplemented with plastic concrete is included in Case II since a cold joint or sand lens with minimal portland cement paste contact may have been inadvertently incorporated into the slab. Credit: John Hart, Iowa DOT 95% payment – can improve pay with grinding/grooving 90% payment – can improve pay with grinding/grooving 85% payment Conventional saw on longitudinal joint Conventional Saws • Saw 8-12 hours after paving • Diamond blades Residue from early entry sawing Early Entry Saws • Transverse and Longitudinal Joints • ¼” and 1/8” width • Saw within 3 hours • Lighter and quieter than conventional saws • Skid plate Blowout at edge of slabPull up of sawcut before edge of slab Sawcut at Edge • Iowa DOT Const. Manual Sec 9.21 • Prevents spalls or blow outs • Prevents sealant from running out of slab edge Late sawing crack Late Sawcut • Sawing must be continuous regardless of weather • Sawing discontinued if crack develops ahead of saw • Article 2301.03, N defines repair for random transverse cracks • Appendix 9-6 Iowa DOT Construction Manual – Recommended Repairs for PCC Cracking Sawcut Depth Iowa DOT: Article 2301.03, N Road Standard PV-101 Construction Manual 9.21, Appendix 9-6 SUDAS: 7010 3.02, J • Road Standard PV-101 (Iowa DOT & SUDAS) defines all joints • Check saw depth and width daily • Inadequate depths may lead to cracking Air blast of joint prior to sealing Joint Sealing Iowa DOT: Article 2301.03, P & Section 4136 Road Standard PV-101 Construction Manual 9.22 and 9.23 SUDAS: 7010 3.02, K • Joint sealer spec DOT Section 4136 • Flush residue within 3 hours of wet saw • Blow residue within 3 hours of dry saw • Moisture and oil free compressed air Installing hot pour sealant Joint Check Worksheet Joint Sealing • Place when air temperature is 40 degrees F or higher • Seal when joint surface is dry • Iowa DOT joint worksheet – PCC Field Inspection manual Steel MIT T2 Scan - Tie Bars and Dowel Bars • NDT or probing during construction for contraction joints • Placed on longitudinal joints • Perpendicular to centerline • Approximately 18 inches from transverse joint California profilograph Smoothness Iowa DOT: Sections 2316 & 2317 I.M. 341 SUDAS: 7010 3.08, reference 2316 • 10’ straightedge – mark areas > ¼”, repair per Iowa DOT 2316 to max 1/8” • Profilometer or inertial profiler • Evaluate within 48 hours after paving • Contractor measures, Owner reviews results Inertial profiler Nine-point core length measuring device Thickness Iowa DOT > 3500 SY MIT scan, April 2021 < 3500 SY probing, April 2021 SUDAS - Iowa DOT I.M. 346 & 347 – Process to identify core locations and measuring thickness/ thickness index MIT T2 Scan Iowa DOT: Articles 2301.04 and 2301.05 I.M. 346, 347 SUDAS: 7010 3.08, D Pay Factors / Price Adjustments SUDAS Air Content Smoothness Thickness Tables 7010.03 7010.04 7010.05 Iowa DOT Air Content Water / Cement Vibrator Frequency Certified Plant Inspection Late Curing Smoothness 2317.05 Primary/Interstate 2316 All others Thickness > 3500 SY MIT scan, April 2021 < 3500 SY probing, April 2021 Pre-Pour Conference • Chain of Command / Responsibilities • Approved Mix Design & Source • Batch Plant Operation / Certification • Paving Schedule Prime Subs • Paving Survey • Hot/cold Weather Protection • Water truck to wet the subgrade/subbase & haul road • Backup Saws • Sampling and Testing Communicate with the contractor when questionable quality/work is observed Compliance • If work is not in compliance with the plans and specs • Inspector notify the Project Manager • Iowa DOT non-compliance Form 830245 • Can result in price adjustment • Const. Manual 2.53 Inspector Checklist • Pre-pour • Pre-pour meeting • Grade & haul road • Steel • Stringline • Equipment • Paving • Wetting the grade • Concrete Delivery Delivery time Water content Mixing • Vibration • Concrete testing Air content Slump Strength Temperature • Pavement verification • Edge slump • Geometry • Steel • Yield • Texture • Station marking • Curing • Sawing • Sealing • Documentation • Post Paving • Joints • Texture • Smoothness Iowa DOT PCC Paving Field Inspection https://iowadot.gov/training/ttcp/training_manuals/PCCField.pdf Resources Section 7010: Portland Cement Concrete Pavement Section 2301 Portland Cement Concrete Pavement Iowa DOT Construction Manual Questions Jerod Gross Senior Project Manager Snyder & Associates, Inc. jgross@snyder-associates.com 515-669-7644 John Hart PCC Field Engineer Office of Construction and Materials, Iowa DOT John.Hart@iowadot.us 515-290-2867 | |
| Real-Time Control of Curing/Research on Productivity in the Concrete Paving Industry | 👤 Dan Zollinger 👤 Omar Swei | New and Evolving Technologies Webinar | 2021 |
| 2021-03-05 | Real Time Curing Control and Construction Productivity Research Q&A Report ‐ 3/5/2021 1. Question to Dan Zollinger. Can we get some examples of variation in curing compound application rate based on In the examples shown in the presentation for Texas, California, and Illinois, the rates were nearly the same (180 sq ft per gallon), yet the EI histories were very different. 2. Is there a way to design/place/cure concrete such that controlled cracks will form between a uniform series of point penetrations (i.e. say a pattern of 1/2" holes)? You mean as a form of crack control? Probably, especially if it is done in conjunction with the method of curing. 3. Expertise‐ did you consider this? Considering there are less and less young people that want to make this their This is one of our key interests as part of this work. Through our early conversations with contractors, one point that has come up is that the labor turnover rate has changed drastically over the last several decades. If we can access historical data as part of our study, we’ll be able to answer how are changes in the labor workforce affecting productivity growth Maybe it’s a matter of how much someone would like to understand a given situation and solutions to solve it. 4. Were there any results from the monitoring done in El Paso's extreme weather environment? Or recommendations? I made a full report for Sundt (if I am not mistaken the government received a copy as well) on the results of the monitoring work carried out there in December. Unfortunately, it was too late to really help them eliminate the cracking issues they had experienced over the last 2 years. The report indicated that the weather conditions were highly variable, and the curing requirements needed to change accordingly to keep up with it. Let me know if you would like a copy, 5. Do you have any advice for curing exposed aggregate concrete roadway? We may not be able to use a curing compound because we are trying to match work that was done between 1931 and 1954. Any suggestions would be This would be a good application for lithium since it will penetrate the medium and not leave a residue. There are also other alternatives that might work as well such as covered curing. You might be surprised how well this would work out. The point being, this type of instrumentation would be very useful in working out a suitable method of curing. 6. Where can you buy the Petra device? The device is not commercially available but soon will be; contact me for more info if you would like to pursue something ‐ we'll figure out how to get a setup for you. 7. How does a GPR help to assess curing? Are you measuring differences in the dielectric and correlating that to low humidity areas to say certain areas are bad? GPR gets us the surface dielectric from point to point and the trend in dielectric with time is related to the EI computed from the base station. Essentially, the correlation is updated every time a GPR scan is done, say every hour. EI is the main parameter to assess the quality of the cure. What's nice about all this is how easy it is to do. 8. Will this research be able to look at "quality improvements?" For example, I may have minimal change in how many SY of pavement I can place in a day with given labor, equipment, etc., but now my road may last 40 years vs 20 years before. Will this be captured or evaluated? . . . .my road will last 40 years vs . . . The answer is yes, both in design and durability. It will have a major impact on fatigue cracking because it will all but eliminate climatic induce cracking damage which has been problematic from site to site and season to season. Joint faulting will become much less to do improved flatness in and around the joints and edges. Seemingly small items will add up to make a huge difference. With the improvements in the performance models we know about, all these features (continued) That is the goal of our work. Our hypothesis and early findings suggest that the decline in productivity may, in part, be a function of the measurement of output. Productivity measures the following ratio: output/input. Ideally, we should measure output in productivity studies as really an outcome. A mile of paved surface provides a service to users. If that pavement can last twice as long (holding constant the amount of inputs), then this improvement should be reflected in the measurement of productivity. If we can track changing pavement design standards, QC/QA programs, and other 9. What are your thoughts regarding a new curing technology for concrete pavements called internal curing (ASTM C1761)? ARA (Applied Research Associates ‐ Champaign, IL) and work done by Dr. Jason Weiss (Purdue/ Oregon State University) on the benefits of internal curing (full‐depth curing). Internal curing is a great technology, but it is another "static" method of curing that works in some circumstances and won't in others. In other words, it's like any other curing method in that it needs to be managed in addition to be evaluated as to the extra costs to apply it versus other less costly options to accomplish the same objective. Internal curing basically attacks the problem from the bottom up and that impacts the capability of balancing set in the slab versus the energy needed to crack the joints. In my opinion, there is still a need to monitor concrete that is being cured 10. The hardest thing to get the contractor to do is consistency in application of curing compound. They almost always apply it too lightly or not at all at spotty locations. I wish there was a way to stress the importance of a uniform final One purpose of the GPR will be to assess uniformity; but, as I allude to in the presentation, I think spraying equipment will need to change in order to make significant improvements. I am referring to single nozzle application as a possible 11. Dan, do you think that the climate zone map and Thornthwaite Moisture Index map need to be recalculated and redrawn/updated to reflect recent climate change trends and, if so, might these redrawn maps impact pavement Interesting question; I understand that the '0' index line moves around from year to year ‐ sometimes to the west and sometimes to the east. Really, the main idea is to realize that some parts of the country are 'dry' while others are 'wet' and that our specifications would reflect this climatic effect. 12. Please describe the crack meter photo. It has some similarity to a maturity meter but records WS, solar, ambient RH and temp, plus dry bulb and dew point temp below the concrete surface at two positions (which helps us to also infer the RH and temperature profiles in the slab). The meter is positioned on the slab to facilitate the collection of that type of data. 13. Do you recommend application of no shrink admixture? The answer to this question may lie in the no shrink technology being used but depends on the how the shrinkage or the temperature induce strain varies with the EI and whether or not a critical combination would develop under field conditions. From what I have seen, these types of admixtures do a good job of mitigating crack potential. The EI would perhaps help define the circumstances of where this type of technology would serve the customer very well and others 14. Please explain more the relation between EI and crack potential and saw window. Thanks. I didn't have the time to explain much on this topic, but it all begins with establishing the EI ‐ shrinkage strain relationship. (I do this regularly on projects that I monitor for quality.) From that relationship, we can estimate the strains associated with the temperature and humidity profiles in the slab (which are also measured by the base station) and tie that back to the amount of warping and curling which leads us to an estimate of the induced stress field in the slab. A comparison to the strength profile over time leads to an assessment of the cracking potential but we do also need to know something | |
| Sustainability and How the Industry Is Reducing Its Environmental Impact | 👤 Lori Tiefenthaler 👤 Jay Whitt | Concrete Lunch & Learn | Winter 2020–2021 |
| 2021-02-24 | Sustainability and How the Industry is Reducing it’s Environmental Impact By Lori Tiefenthaler and Jay Whitt Leading the Way to Carbon Neutrality Evolution of Sustainability – Developing Expertise Products and Technology Discussion ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt3 Why do we collectively care about Sustainability? S U S T A I N A B I L I T Y ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt4 Lehigh Hanson is part of the HeidelbergCement Group one of the worldwide market leaders in the building materials sector HeidelbergCement >50 countries >3,000 locations >54,000 employees World leader in the vertical integration # 1 worldwide in aggregates: • 600 production sites for sand, gravel and crushed rock (200+ Lehigh Hanson) # 2 worldwide in cement • 160 cement plants/grinding mills (20+ Lehigh Hanson) # 3 worldwide in ready-mixed concrete • 1.700 ready mixed concrete plants (200 Lehigh Hanson) ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt5 Products and Technology: Developing Sustainable Solutions in Our Markets It is difficult to have same offering in each market; however we strive to serve all of our areas with at least one sustainable cement. User of recycled materials (Circular Economy): • Slag • Fly Ash Blended Cements – EcoCem Low-carbon cement types: • Portland Limestone Cement (IL) - EcoCemPLC • Composite Cements (IT) - EcoCemPLUS • Slag and Portland (IS) • Fly Ash and Portland (IP) Lehigh Cement: Cement and Slag facilities - including JVs Cement’s environmental impacts are typically at least 80% of Concrete’s carbon footprint https://www.lehighhanson.com/sites/lehigh-cement-company?utm_source=GlobSum&utm_medium=booth&utm_campaign=UBLehigh&utm_term=1220 ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt6 Leading the Way to Carbon Neutrality Science Based Targets Initiative Our goal is to realize the vision of carbon-neutral concrete at the latest by 2050 2019 2030 2050 -30% reduction 1990 baseline 2025 ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt7 HeidelbergCement 2030 Commitments “We adhere to international human rights, anti-corruption and labour standards and co-operate pro-actively in an open and transparent manner with all our stakeholders.” Ensuring Compliance and Creating Transparency “We are committed to supporting the social and economic development of our neighbouring communities and ensure transparent communication to all our stakeholders.” Being a Good Neighbour “We conserve our natural reserves by continuously increasing the use of alternative resources as substitutes for natural raw materials.” Enabling the Circular Economy “We are committed to fulfilling our share of the global responsibility to keep temperature rise below 2°C, and we will continue to reduce our impacts on air, land and water.” Reducing our Environmental Footprint “We are committed to continuously enhancing the occupational health and safety conditions of our employees, contractors, and third parties.” Achieving Excellence in Occupational Health and Safety “We will ensure sustainable profitability through the effective management of all processes and resources and the continuing innovation of products and services.” Driving Economic Strength and Innovation “We are committed to fulfilling our share of the global responsibility to keep temperature rise below 2⁰ Celsius, and we will continue to reduce our impacts on air, land and water.” https://www.lehighhanson.com/about/sustainability?utm_source=GlobSum&utm_medium=pres&utm_campaign=webSD&utm_term=1220 ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt8 Our Industry is developing a roadmap S U S T A I N A B I L I T Y ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt9 Why PLC? 2030 Sustainability Commitments Lehigh Wants to Be A Leader in Sustainability We have aligned our Sustainability Commitments with the UN Sustainable Development Goals (SDG) enacted in 2015 by the UN General Assembly, which have been adopted by all 193 member states. Their aim is to end extreme poverty, fight injustice and to protect our planet with 17 goals set out for 2030. − For Lehigh: 30% Reduction in Carbon Emissions by 2030 PLC is an immediate strategy that can be implemented to tackle carbon emissions; it’s something that we can do NOW. − Increasing CO2 efficiencies at cement plants (Mitchell’s K4, etc.) Production and use of PLC is a proactive step that can be taken to promote GREEN BUILDING. − Lower “Global Warming Potential” value for use in EPD’s (Environmental Product Declaration) with PLC ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt10 Cement/Concrete Products and Technology: Sustainable Solutions At least 80% of HeidelbergCement’s Research and Development Investments are Sustainability Driven Reduction of clinker content in cement and concrete Alternative cementitious systems Levers for Lower Carbon Concrete Use of fly ash other recycled fines in cement production Use of SCMs: slag cement for basements and massive construction pours ALTERNATIVE RAW MATERIALS Biomass (zero emissions) Other fuels waste oil, tires RDF ALTERNATIVE FUELS sewage sludge Wood, paper, carton animal meal, animal fat animal bone meal Heatcrete® is a special concrete with high thermal conductivity for energy storage. ENERGY STORAGE & TRANSMISSION Powercrete® increases the efficiency of underground power cables with its high thermal conductivity. https://www.lehighhanson.com/products/cement/tx-active?utm_source=GlobSum&utm_medium=booth&utm_campaign=TXActpg&utm_term=1220 ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt11 LEED (1998-present) • Rating system • Credit driven • 75% Operational (water/Energy efficiency) • Materials (10%) Global Warming • Climate Change • Paris Agreement (2016) • GHG emissions • GWP in kg of CO2 eq • Cement Industry 5-8% global emissions – due to resilience necessity Operational Carbon Emissions Embodied Carbon Emissions Sustainability Evolution – Developing Expertise Environmental Product Declaration (2015) • Product/Plant EPD • Embodied Carbon Accounting • Reducing GWP kg of CO2 • Low Carbon Concrete • Setting Baselines Transparency ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt12 Environmental Product Declaration (EPD) “a transparent, verified report used to communicate the environmental impact (e.g., resource use, energy, emissions) associated with the manufacture or production of construction materials…” What are the Benefits of EPD’s Provide verifiable and transparent information on life-cycle environmental impact data for materials or products Allow meaningful comparisons of the environmental performance of materials Identify areas for environmental performance improvement, encouraging industry efficiency T R A N S P A R E N T R E P O R T I N G O F E N V I R O N M E N T A L I M P A C T S - E P D Source: FHWA https://www.fhwa.dot.gov/pavem ent/sustainability/hif19087.pdf https://www.fhwa.dot.gov/pavement/sustainability/hif19087.pdf https://www.fhwa.dot.gov/pavement/sustainability/hif19087.pdf ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt13 Environmental Product Declarations (EPD) – What’s Included to Make Them Includes 72 mixes; 6 categories; 2500-8000 PSI Updated Cement Industry average in Q1 2021 will have a PLC 2019 <13% GWP than 2014 T R A N S P A R E N T R E P O R T I N G O F E N V I R O N M E N T A L I M P A C T S - E P D ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt14 Page 2 of 3 What is on an EPD T R A N S P A R E N T R E P O R T I N G O F E N V I R O N M E N T A L I M P A C T S - E P D ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt15 Products and Technology: Using Portland Limestone Cement (PLC or Type IL) Benefits of Using Type IL Concrete Producers Contractors/Customers Public Reduced Energy impact from cement Improved Consistency and workability Fewer CO2 Emissions Lower Global Warming Potential (GWP) > Durability More Durable Concrete with SCMs Better Chemical Control Particle packing optimized Cleaner Air Synergies with SCMs Lower Carbon Concrete Concrete has Lifetime CO2 Uptake EcoCem®PLC is a blended portland cement with up to 15% limestone and as much as 10% less embodied carbon. Link: www.concretejustgotgreener.com 2 0 1 0 https://www.lehighhanson.com/products/cement/EcoCemPLC?utm_source=GlobSum&utm_medium=booth&utm_campaign=EcoCempg&utm_term=1220 http://www.concretejustgotgreener.com/ ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt16 The primary advantage is that it allows for a reduction in CO2, typically up to 10% PLC is a simple, straight forward switch in your operation; essentially “plug n play” Pull OPC powder out of your mix, and replace it with PLC PLC provides you an opportunity to “Go Green” and increase your sustainability without spending money on capital investments for specialized systems at your ready mixed concrete plants Caption Calibri Light 10 pt. P O R T L A N D L I M E S T O N E C E M E N T R E S O U R C E S Advantages of PLC What does PLC do for me? https://www.greenercement.com/ https://www.greenercement.com/ ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt17 PLC or Type IL: Current Status • Lehigh Cement - Seattle market reaching 100% conversion to PLC • Department of Transportation in 32+ States have now approved the use of PLC or Type IL cement. IDOT 2013-14 FAA US Army Corps of Engineers • Many Cities and Counties are adopting PLC into their local specifications • Engineers and Architects have begun adding ASTM C 595 to their specifications • PLC is being used on many high profile projects, where reducing carbon footprint is part of their goal • Performance concrete rather than specified concrete is bringing additional value to the owner and contractor • Combining PLC with recycled products is leading the way in sustainable design. https://www.greenercement.com/ https://www.lehighhanson.com/products/cement/EcoCemPLC?utm_source=GlobSum&utm_medium=booth&utm_campaign=EcoCempg&utm_term=1220 ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt18 Links to PLC fact sheets, Research Reports and for the Architects, Engineers and Specifiers, there is a link to “How to Specify PLC”. Portland Cement Association: https://www.greenercement.com/ https://www.greenercement.com/ To understand how PLC works, we need to look at how it’s made. What is a PLC? ‒ Type IL blended cement in ASTM C595/AASHTO M240 ‒ Allowed 5% to 15% limestone by mass ‒ Typically made from the same clinker as C150 cement; PLC just has ~6% more limestone. ‒ Designed for equivalent performance. ~ 5-10% additional limestone added to the Finish Mill, replacing clinker at 1:1. Ground Finer for equivalent performance Optimized Sulfate for Set Control ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt20 The LS occupies the finest part of the cement Particle Size Distribution (PSD) spectrum Keys to PLC Performance ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt21 RE-Carbonation benefits quantifiable through EPDs • HeidelberCement: significant carbonation R & D • HeidlbergCement Research Labs: Products and Technology: Re-Carbonation Ready - Embodied Carbon Emission Reduction Accounting Soon iLab in Bergamo, Italy Global Cement and Concrete Association good source on this topic https://www.sciencedirect.com/science/article/pii/S0008884619301929#! https://www.linkedin.com/pulse/re-carbonation-important-chapter-concrete-carbon-circular-minson/?trackingId=CbmCynbIWZsADd1kiIJkdQ%3D%3D ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt22 S U S T A I N A B I L I T Y Sustainable Concrete Pavements – Whole Life Carbon Accounting Life Cycle Assessment (LCA) – Use-phase impacts are often dominant (energy, CO2 etc.) Pavement Vehicle Interaction (PVI) – roughness, texture and deflection (stiffness) Useful tool for agencies to reduce GHG emission. Increasing the stiffness using 10% resurfacing in the network per year 18% reduction of GHG emissions from the pavement network, or 440 Mt CO2eq, over a 50-years. (AzariJafari et al.) Albedo – Mitigating Urban Heat Island and Climate Change Reflective pavements could lower air temperatures by more than 2.5oF, and offset CO2 equivalent of 4 million cars per year Carbon Uptake – can offset 5.4% of GHG emissions associated with clinker production! 5.8 Million metric tons CO2 can be sequestered by US pavement network (AzariJafari et al.) ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt23 Lehigh Project and Case Studies using EcoCemPLC™ P O R T L A N D L I M E S T O N E C E M E N T P R O J E C T S ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt24 P L C P R O J E C T S First Iowa DOT PLC Pavement Project - 2013 Concrete was a Ternary Mixture: Iowa DOT QMC Mix Design Type IL(10) Cement and 20% Class C Fly Ash 19,270 yd3 Concrete 4,274 Tons Type IL(10) Cement Pavement: 10 ½ inch Doweled Pavement 4 Miles, 2 East Bound Lanes w/ Turn Lanes Placed in 12 days: May 24-June 19, 2013 ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt25 P L C P R O J E C T S Central Iowa Expo Center: Boone IA Concrete Mix Information: Iowa DOT QMC Mix Design Type IL(10) and 20% Class C Fly Ash 2,536 yd3 Concrete 553 Tons Type IL(10) Cement Pavement: 6 inch Plain Pavement 19 Mile Haul from Concrete Plant! Placed: June 21-28, 2013 ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt26 P L C P R O J E C T S Lehigh Plant – Leeds, Alabama 2009-10 Creek Relocation – 26,800 CY Soil Stabilization, Creek Lining, Tunnel Under Plant 2010 New Cement Silo – 5,100 CY Slip Formed – 5100 CY (40% Slag) Intricate Structural Design ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt27 P L C P R O J E C T S City of Leeds, AL Streets 2013 & 15 Streets – 500 CY (20% F-ash) City of Leeds Paving – 400 CY ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt28 P L C P R O J E C T S City of Leeds, AL Streets ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt29 P L C P R O J E C T S Indiana First PLC Pavement Project - Patching Project: completed Sept. 2020 Project location: I-65 Columbus, IN Comments from the project: Plastic properties of the concrete were very consistent and stable Expected project duration was 5-6 Saturdays; due to the performance of the PLC concrete, the project was completed in 3 Saturdays. ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt30 P L C P R O J E C T S Indiana First PLC Pavement Project - Patching Project: completed Sept. 2020 Project location: I-65 Columbus, IN Patch Concrete: 284 Cubic Yards Concrete Patch Mix design - typically patching mix Replaced ordinary cement with PLC (like for like) Specs: 625psi flex in 3days (typically 550psi) Concrete Test Results: 425 flex psi spec to open to traffic; with maturity, this was attained in 12-15 hrs. The 3d flex spec was 625 psi; the average for the project was 730 psi in 3 days. ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt31 Indiana First PLC Pavement Project - Patching P L C P R O J E C T S Flowable fill: 68 yards First time DOT was using a higher performance flowable mixture Flowable Fill: 8 hour DCP blow count (typically a 3 day spec – 30 blows). New mix met in ~2.5 hrs ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt33 Resources for You ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt34 Portland Cement Association: https://www.greenercement.com/ The Site Contains a CO2 Calculator – How much CO2 can you save by using PLC on a project? There is an Option for Lane Miles as Well. https://www.greenercement.com/ ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt35 P O R T L A N D L I M E S T O N E C E M E N T R E S O U R C E S ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt36 P O R T L A N D L I M E S T O N E C E M E N T R E S O U R C E S A Green Cement | PLC | Portland Limestone Cement - YouTube https://www.youtube.com/watch?v=dizQpwTMPEo https://www.youtube.com/watch?v=dizQpwTMPEo ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt37 P O R T L A N D L I M E S T O N E C E M E N T R E S O U R C E S ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt38 Specifying PLC P O R T L A N D L I M E S T O N E C E M E N T R E S O U R C E S ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt39 Increase Your Knowledge https://www.fhwa.dot.gov/pavement/sustainability/ Greenercement.com – Portland Limestone Cement CSHubMIT – YouTube – MIT Concrete Sustainability Hub Public Videos Home | Concrete Sustainability Hub (mit.edu) – Website with research Briefs https://buildwithstrength.com/education/ - National Ready Mix Concrete Association Educations – On demand videos carbonleadershipforum.org – Carbon Leadership Forum buildingtransparency.org – CLF’s tool for viewing EPDs gccassociation.org – Global Cement and Concrete Association nrmca.org/association-resources/sustainability/epd-program - NRMCA Home - Build With Strength : A Coalition of the National Ready Mixed Concrete Association linkedin.com/groups/1807540/ - Women in Concrete Alliance https://www.linkedin.com/company/lehigh-hanson/mycompany/ Lehigh Hanson Linked In - #knowledgeIsStrength Environmental Product Declarations (EPDs) - Lehigh Hanson, Inc. - Lehigh Hanson and Industry Wide EPDs Resources for Information and Learning on Concrete Sustainability and Transparency C O N S T R U C T I O N S U S T A I N A B I L I T Y R E S O U R C E S https://www.fhwa.dot.gov/pavement/sustainability/hif19087.p df https://www.greenercement.com/acceptance https://www.greenercement.com/acceptance https://www.youtube.com/user/cshubMIT https://cshub.mit.edu/ https://buildwithstrength.com/education/ https://carbonleadershipforum.org/ https://www.buildingtransparency.org/en/ https://gccassociation.org/ https://www.nrmca.org/association-resources/sustainability/epd-program/ https://buildwithstrength.com/ https://www.linkedin.com/groups/1807540/ https://www.linkedin.com/company/lehigh-hanson/mycompany/ https://www.lehighhanson.com/resources/epds ICPA – CP Tech Center Webinar Sustainability by Lehigh Hanson | 2.19.2021 | Lori Tiefenthaler and Jay Whitt40 Thank You! Questions? Jay Whitt – jay.whitt@lehighhanson.com Lori Tiefenthaler - lori.tiefenthaler@lehighhanson.com https://www.lehighhanson.com/about/sustainability?utm_source=GlobSum&utm_medium=pres&utm_campaign=webSD&utm_term=1220 mailto:jay.whitt@lehighhanson.com mailto:lori.tiefenthaler@lehighhanson.com Slide Number 1 Slide Number 2 Why do we collectively care about Sustainability? Lehigh Hanson is part of the HeidelbergCement Group �one of the worldwide market leaders in the building materials sector Products and Technology: Developing Sustainable Solutions in Our Markets Leading the Way to Carbon Neutrality Slide Number 7 Our Industry is developing a roadmap Why PLC? 2030 Sustainability Commitments Cement/Concrete Products and Technology: Sustainable Solutions�At least 80% of HeidelbergCement’s Research and Development Investments are Sustainability Driven Sustainability Evolution – Developing Expertise Environmental Product Declaration (EPD) Environmental Product Declarations (EPD) – What’s Included to Make Them Slide Number 14 Products and Technology: Using Portland Limestone Cement �(PLC or Type IL) Advantages of PLC PLC or Type IL: Current Status Slide Number 18 Slide Number 19 Slide Number 20 Products and Technology:�Re-Carbonation Ready - Embodied Carbon Emission Reduction Accounting Soon Sustainable Concrete Pavements – Whole Life Carbon Accounting Lehigh Project and Case Studies using EcoCemPLC™ First Iowa DOT PLC Pavement Project - 2013 Central Iowa Expo Center: Boone IA Lehigh Plant – Leeds, Alabama City of Leeds, AL Streets City of Leeds, AL Streets Indiana First PLC Pavement Project - Patching Indiana First PLC Pavement Project - Patching Indiana First PLC Pavement Project - Patching Resources for You Portland Cement Association: https://www.greenercement.com/ Slide Number 35 Slide Number 36 Slide Number 37 Specifying PLC Increase Your Knowledge Slide Number 40 | |
| Troubleshooting Concrete Projects | 👤 Jerod Gross | Concrete Lunch & Learn | Winter 2020–2021 |
| 2021-02-19 | Troubleshooting: Concrete Projects February 5, 2021 Jerod Gross, PE, LEED AP Representing the CP Tech Center https://cptechcenter.org/events/concrete-lunch-and-learn/ Winter 2020-2021 Concrete Lunch & Learn Webinars • December 11, 2020 - PEM and Reduced-Cement Pavement Mixes in Iowa, Dan King, ICPA & Todd Hansen, Iowa DOT Reduced-cement concrete pavement mixes used in Iowa and how this fits into the Performance-Engineered Mixtures (PEM) program and testing regime. • January 8 - PCC Overlays – Fabric and Fiber, Tom Cackler, Ingios Geotechnics & Dan King, ICPA Discussion on new technologies for concrete overlays, including fiber-reinforced concrete and geotextile fabric interlayers, and their applications on recent Iowa projects. • January 22 - Subgrade & Subbase: Iowa DOT Research and Next Steps, Melissa Serio, Iowa DOT Hear how the Iowa DOT is working to improve design and testing of subgrade and subbase layers for concrete pavements. • February 5 - Troubleshooting: Concrete Projects, Jerod Gross, Snyder & Associates, Inc. Tips, tricks and advice for sorting through common problems during concrete pavement construction. • February 19 - Concrete Industry and the Environment – Sustainability and How Concrete is Reducing its Environmental Impact, Lori Tiefenthaler, Lehigh Hanson Learn how the cement and concrete industries are moving forward in the 21st century to adapt to environmental needs and reduce their carbon footprint. • March 5 - Construction Inspection – Just in Time Inspection Refresher, John Hart, Iowa DOT & Jerod Gross, Snyder & Associates, Inc. Whether you will be building or inspecting, gear up for a new year of concrete pavement construction with a refresher on best practices. 2 https://cptechcenter.org/events/concrete-lunch-and-learn/ https://cptechcenter.org/performance-engineered-mixtures-pem/ Is a Concrete Crack a Failure? All concrete cracks during curing and shrinkage We control the cracks with sawcuts Tight (non-working) cracks can remain 3 Not All Cracks are Created Equal Many times, cracks have no detrimental effect on long-term pavement performance. Map cracking and other near surface cracking usually does not impact pavement life. Cracks that extend full-depth of the slab must be either “non-working” or repaired. 4 Duke Cares … Duke wants good concrete Lets go through some Troubleshooting items 5 Too Early Opening The early test drive….it happens What do you do about tracks in the pavement? 6 Too Early Opening Shallow scarring/surface depressions are correctable Most do not harm the integrity of the pavement 7 Too Early Opening Large depressions and edge damage need replacement 8 Too Early Opening “-man drives through fresh cement” 9 Too Early Opening Shallow depressions can be corrected with diamond grinding Deeper ruts should be repaired • Partial-depth • Full-depth 10 What’s wrong here? Ensure bars are horizontal Cure the pavement 11 Longitudinal Cracking Excessive pavement width Be careful with gutter joints Sawcut 12 Gutterline joint Longitudinal Cracking Excessive panel width in transition area 13 Longitudinal Joint Gutterline joint Longitudinal Cracking Excessive panel width in transition area 14 Longitudinal Cracking 15 Excessive panel width in transition area Longitudinal Cracking 16 Excessive panel width in transition area Longitudinal Cracking 17 Excessive panel width in transition area Longitudinal Cracking Transition gutterline jointing 18 Longitudinal Cracking •Use of gutter joints not recommended for T < 9” •Thinner pavements may not crack at gutter joint, causing longitudinal cracks at mid-panel •Saw depth must be T/3 Longitudinal Spacing 6.5’ -12.5’ for T < than 9“ 14.5’ max. for T > 9” 19 SUDAS 5G-2 Joint Layout 20 SUDAS 5G-2 Urban Joint Layout Jointing transition areas Chapter 5G-3 Third-Point Jointing Quarter-Point Jointing (Eccentric and Concentric Widening) 21 Jointing Tips http://wikipave.org/index.php?title=Joint_Layout OR Google: ACPA Wikipave joint layout Rules for Joint Layout 22 http://wikipave.org/index.php?title=Joint_Layout Jointing Tips ACPA Wikipave - Joint Layout http://wikipave.org/index.php?title=Joint_Layout 23 Jointing Tricks • Longitudinal joint termination (dead end joints) • Core hole 24 Jointing Tricks • Longitudinal joint termination (dead end joints) • Add tie bars Optional tie bars to hold potential crack tight FHWA Technical Advisory Concrete Pavement Joints T 5040.30, Jan. 2019 25 Snow Crackers 26 Snow Crackers • Longitudinal crack from frost heave is the likely culprit • New pavement • Recommended to remove all snow or no removal at all 27 Snow Crackers • New pavement • Curb wasn’t backfilled at the time, added moisture • Frost heave 28 ACPA Snow Crackers • New pavement • Radial cracking 29 ACPA Snow Crackers • New pavement • Radial cracking 30 ACPA Cracking from Settlement / Poor Support 31 Corner Cracking Pavement too thin & saturated subgrade 32 Tie Bar Displacement 33 Tie Bar Displacement • Verify steel at joint • Sawcut and remove exposed steel • Surface patch • Install tie bars by cross-stitching 34 What happened? If it happens: Do Nothing Diamond grind Surface sealers Plastic Shrinkage 35 Preparation: Watch the weather Apply adequate cure quickly What happened? Sawcut to shallow Check sawcut depth 36 Joint Sawing • Check saw cut • Check saw depth • Maintain blades and equipment • Tighten and replace blades • Skid plate on early entry saw • If longitudinal isn’t deep enough, may have time to re-saw 37 ACPA Combined Shrinkage and Curling Stresses If the sum of stresses exceeds established strength, cracks can develop. www.hiperpav.com 38 http://www.hiperpav.com/ What Happened? 39 Partial Depth Repair Joint not restored properly Expansion & contraction Patch de-bonded Construction – Partial Depth Repairs 35 Critical to Restore the Joint • Better results with compressive relief material (board) • Saw to full depth of patch only if board cannot provide complete separation of patch material on both sides of joint (Iowa DOT) • SUDAS requires board Chapter 5 - Concrete Pavement Preservation Guide Construction – Partial Depth Repairs 35 Chapter 5 - Concrete Pavement Preservation Guide Duke Cares … • Duke wants good concrete… • Low water/cementitious material ratio • w/cm 0.40 – 0.42 • Good air distribution • Target 8%, 0.008 in. spacing • Supplementary Cementitious Materials SCMs (fly ash, slag) • Durable & well graded aggregates • No Magnesium Chlorides • Adequate curing 42 Duke Cares … • If one or more parameter is off, we have risk for material related distress 43 Don’t Add Water Like This 44 No, No, No Ensure Uniform and Adequate Cure 45 Paint it White! Aggregate Stockpile Management Contamination - mud balls On the tires Dig too deep In the aggregate 46 Repairs for PCC Cracking 47 Iowa DOT Construction Manual Appx 9-6 Plastic Shrinkage Cracking 48 Do Nothing Diamond Grind Surface sealer Transverse Cracking (mid-panel) 49 Saw/route and seal crack if undoweled* Full-depth repair if doweled Transverse Cracking (<5’ from joint) Sawed too late 50 Saw/route and seal the crack if undoweled Full-depth repair if doweled 51 Transverse Cracking (<5’ from joint) Spalled Transverse Joint 52 Partial-depth repair Longitudinal Cracking (<1’ from joint) 53 Saw/route and seal the crack or cross- stitch the crack Epoxy sawed joint if uncracked 54 Longitudinal Cracking (> 5’ from joint) Saw too late or not deep enough Cross-stitch the crack* *If working crack Controlling Popouts 55 Lightweight materials sneak around from the grout box if head is too low Good example of keeping enough material in front of paver Controlling Popouts 56 May result from insufficient material in front of paver Mitchell County, Iowa 57 Boxouts 58 Protect new pavement when removing forms from boxouts Rain Damage 59 Cover it and leave alone Do not finish rain water into the surface Diamond grind to re-establish texture 3 levels of rain damage – Iowa DOT Rain Damage 60 Case 1 Case 2 Case 3 Texture is absent from practically all of surface area. Surface appearance may have a "sandy" appearance or may be "pock" marked from the rain droplets. An occasional edge repair may be required due to excess edge slump or from edge rounding. Small areas along edge may have coarser particles of fine aggregate exposed. Surfaces finished in the rain or after a rain are also included in Case I. This includes any manipulation of the pavement surface including mopping of the surface to attempt to remove rainwater or retexturing while rainwater is present. Surface mortar has been practically all removed to an extent that coarse particles of the coarse aggregate fraction are visible. Considerable erosion of edges has occurred, but not to an extent that pavement width is affected. Intermittent edge repair may be required as well as some surface patching of slight troughs or depressions that may have formed in pavement surface due to flowing water. Texture is totally absent from the surface and cement mortar has been eroded to an extent that coarser particles of the fine aggregate fraction are generally exposed. Some slight troughs or depressions are apparent, exposing coarse aggregate particles, but this damage is confined to a limited area or randomly spread intermittently throughout damaged area. Some edge repairs may be required to restore eroded edges. Surface mortar that was removed by rain water, but later replaced or supplemented with plastic concrete is included in Case II since a cold joint or sand lens with minimal portland cement paste contact may have been inadvertently incorporated into the slab. Credit: John Hart, Iowa DOT 95% payment 90% payment 85% payment RESOURCES 61 • Iowa DOT PCC Paving Field Inspection https://iowadot.gov/training/ttcp/training_manuals/PCCField.pdf • ACPA WikiPave • SUDAS Section 7010 • Iowa DOT Section 2301 • CP Tech Center cptechcenter.org https://iowadot.gov/training/ttcp/training_manuals/PCCField.pdf Thank you Jerod Gross, PE, LEED AP jgross@snyder-associates.com 515-669-7644 Troubleshooting: Concrete Projects�February 5, 2021 Slide Number 2 Is a Concrete Crack a Failure? Not All Cracks are Created Equal Duke Cares … Too Early Opening Too Early Opening Too Early Opening Too Early Opening Too Early Opening What’s wrong here? Longitudinal Cracking Longitudinal Cracking Longitudinal Cracking Longitudinal Cracking Longitudinal Cracking Longitudinal Cracking Longitudinal Cracking Longitudinal Cracking � Joint Layout� Urban Joint Layout Jointing Tips Jointing Tips� Jointing Tricks� Jointing Tricks� Snow Crackers Snow Crackers Snow Crackers Snow Crackers Snow Crackers Slide Number 31 Slide Number 32 Tie Bar Displacement Tie Bar Displacement What happened? What happened? Joint Sawing Combined Shrinkage and �Curling Stresses What Happened? Construction – Partial Depth Repairs Construction – Partial Depth Repairs Duke Cares … Duke Cares … Don’t Add Water Like This Ensure Uniform and Adequate Cure Aggregate Stockpile Management Repairs for PCC Cracking Plastic Shrinkage Cracking Transverse Cracking (mid-panel) Slide Number 50 Slide Number 51 Spalled Transverse Joint Longitudinal Cracking (<1’ from joint) Slide Number 54 Slide Number 55 Slide Number 56 Mitchell County, Iowa Slide Number 58 Slide Number 59 Slide Number 60 RESOURCES Slide Number 62 | |
| Understanding the application/benefit of fiber reinforcement in concrete | 👤 Jeff Roesler | Concrete Pavement Technology Tuesday Webinar | 2021 |
| 2021-02-17 | Benefit and Application of Fiber Reinforcement in Concrete Pavement Jeffery Roesler, Ph.D., P.E. University of Illinois Urbana Champaign February 9, 2021 CPTech Center 2021 Webinar Series Slide 1 Acknowledgements Amanda Bordelon, Ph.D., P.E. (Utah Valley University) Armen Amirkhanian, Ph.D., P.E., (University of Alabama) Alexander Brand, Ph.D. (Virginia Tech) Partial Funding /oversight for this project provided by: TTCC/Fiber Reinforced Concrete OverlayProject Reinforced Concrete for Pavement Technical Advisory Committee National Concrete Consortium National Concrete Pavement Technology Center (Iowa State) Peter Taylor, Steve Tritsch, etc. Snyder and Associates, Inc. Jerod Gross, Dale Harrington 3 Presentation Overview FRC pavement resources General overview of macrofibers in concrete pavements Macrofibers types available Effect on fresh and hardened properties Test methods to specify macrofibers Construction best practices & guidelines Applications of FRC to concrete pavements 4 4 (a) (b) Driveway Rehabilitation (2003) 5lb/cy of Synthetic Macrofibers FRC Pavement Overlay Report: T.O.C. 1 Introduction 2 Report Objective 3 FRC Pavement Background 4 Types and Characteristics of Fibers 5 Behavior of FRC Materials for Concrete Pavements 6 Concrete Pavement Design Methodology with FRC Materials 7 Construction Modifications with FRC Pavement Overlays 8 FRC Test Methods 9 Example of FRC Overlay Specifications 10 Miscellaneous Topics on FRC Overlays 11 Summary of FRC Overlays for Pavements References Appendix A of Residual Strength Estimator Software for FRC Concrete Overlay 6 Chapter Topic https://intrans.iastate.edu/app/uploads/2019/04/FRC_overlays_tech_ovw_w_cvr.pdf Fiber Reinforce Concrete Overlay Tech Brief Tech Brief FRC for Pavement Overlays (8 pages) https://intrans.iastate.edu/app/uploads/2019/10/MAPbriefMarch2019.pdf Fiber types, mixture proportions, properties, slab performance, structural design, construction, testing, residual strength 7 0 1 2 3 4 5 6 0 0.5 1 1.5 2 2.5 3 Beam Deflection (mm) .35% Hooked End Steel Fiber .50% Crimped Steel Fiber .32% Synthetic Fiber .48% Synthetic Fiber Plain ASTM C1609 12 Concrete Overlay Guide, Third Edition (4th edition soon) Contents Overview of Overlays Overlay types and uses Evaluations & Selections Six Overlay Summaries Design Section Misc. Design Details Overlay Materials Section Work Zones under Traffic Overlay Construction Accelerated Construction Specification Considerations Repairs of Overlays http://www.cptechcenter.org/technical library/documents/Overlays_3rd_edition.pdf Guide to Concrete Overlays of Asphalt Parking Lots (2012) Contents: Parking Lot Features Existing Pavement Condition Concrete Overlay Design Jointing Parking lot details Materials Construction Fibers What is new with FIBERS? 1. New fiber technologies being developed New synthetic fibers (shape, length, surface texture) Materials 2. New admixtures and new mixing techniques to aid dispersion of fibers Plasticizer admixtures Batching process improvements 3. Pavement design tools Thickness, slab size, crack width, crack deteriorate rates 4. Economically viable Volume fractions often < 0.5% to keep initial cost low 10 Fiber Types (Sizes) Micro Fibers Material: Synthetic, natural or glass fibers Dosage: 0.05 to 0.2% by volume 0.75 to 3 lb/cy Fiber dimensions: Diameter < 0.012 inch Length < 0.5 inch MACRO FIBERS Material: Synthetic or steel Dosage: 0.2 to 0.5% by volume 3 to 8 lb/cy (synthetic) or 25 to 75 lb/cy (steel) Fiber dimensions: Diameter > 0.012 inch Length 0.5 to 2.5 inches 11 Benefits & Challenges of FRC Pavements FRC in rigid pavements since 1970s U.S. Army (airfield) tests (Parker 1974) Vf =1 to 2% steel fibers with higher cement content FRC benefits from past studies: Improve cracking resistance & load carrying capacity of slabs Reduce slab thickness (30% to 50%) based Increase allowable joint spacing in design based Reduce or limit crack widths and crack deterioration rates Less joint spalling in pavements Challenges: Several premature slab failures in field (Rollings 1993) Dosage amount and type of fiber chosen on experience Structural Design benefit was NOT effectively standardized 12 Concrete Properties with Fiber Reinforcement (for Vf< 1.0% typical in pavements) FRC does not increase tensile or compressive strength of plain concrete FRC does not increase or decrease flexural strength or splitting strength of plain concrete beams FRC does increase concrete toughness/strain capacity 13 Fiber Bridging Mechanism Fiber bridging zone Non-linear fracture process zone Aggregate bridging zone Micro-crack zoneTraction-free macro-crack How does FRC effect mixture properties? (Hardened Properties) Strength (tensile, compressive, flexural) Should see no different between plain and FRC If you see a reduction, may have honeycombing or fiber clumping/balling/compaction issues Drying shrinkage Free shrinkage tests do not show any change Restrained shrinkage tests should be significantly longer lasting or lower strains at cracking Fatigue (flexural) stress ratio FRC mixture will provide similar to longer number of fatigue cycles at failure (increased endurance limit) 16 Monotonic Load Deflection of FRC Slab Plain vs Synthetic Macrofibers 0 25 50 75 100 125 150 175 200 225 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Average Interior Maximum Surface Deflection (mm) L o ad ( k N ) Plain 0.48% Synthetic Macro Fiber 0.32% Synthetic Macro Fiber 17 Plain Effect of Macrofibers on Concrete Slab Flexural Capacity Macrofiber addition improve flexural cracking load over plain concrete slab. Increase in FRC slab capacity over plain concrete slab Synthetic Macrofiber#1 (0.48%) 32% Synthetic Macrofiber#1 (0.32%) 25% Hooked Steel Macrofiber (0.35%) 31% Crimped Steel Macrofiber (0.50%) 55%* *higher concrete strength 18 How does FRC effect mixture properties? (Fresh Properties) Slump/workability Expect a decrease with addition of fibers (less slump, harder to work with) Can counteract this with water reducers or mixture adjustments (add more paste, reduce aggregate size) Air content You may see some change due to fibers Can counteract with adjustments to air entraining admixture Unit weight or other properties No significant difference 20 How to specify macrofibers in concrete pavement? Specific FRC mixture must: Be tested according to ASTM C1609 12 Achieve a minimum f150 residual strength value (design target) Be tested at a certain age (e.g., 7 or 28 days) Be a certain specimen size (e.g., beam) 22 ASTM C1609 12 testing a 6x6x18 in3 flexural beam Flexural Performance of FRC ASTM C1609 12 Beams: 6 in x 6 in (15x15cm) Span (L): 18 in (45cm) L/150 = 0.12 in (3 mm) 23 ASTM C1609 12 MOR = · = · , = · · · Flexural Beam Results 150x150x550mm 0 1 2 3 4 5 6 0 0.5 1 1.5 2 2.5 3 Beam Deflection (mm) .35% Hooked End Steel Fiber .50% Crimped Steel Fiber .32% Synthetic Fiber .48% Synthetic Fiber Plain 24 2bd PL MOR = · Flexural and Residual Strength Values* Flexural Strength MOR psi [MPa] f150 psi [MPa] R150 (%) Plain Concrete 686 [4.73] 0 0.0 0.32% Synthetic 680 [4.69] 126 [0.87] 18.0 0.48% Synthetic 699 [4.82] 225 [1.55] 32.0 0.35% Hook Steel 679 [4.68] 234 [1.61] 34.5 0. 50% Crimp Steel 766 [5.28] 184 [1.27] 24.0 *Actual values measuring according to ASTM C1609 07 (different roller assembly) 25 Examples of parameters that effect f150 values f150 value psi [MPa] Mixture Fiber type Age tested days Fiber volume % of total concrete volume Fiber dosage amount lb/cy [kg/m3] 90 [0.65] Mix 1 Synthetic Fiber Option 1 14 0.27% 4.1 [ 2.4] 155 [1.05] Mix 1 Synthetic Fiber Option 1 28 0.38% 5.8 [ 3.4] 160 [1.10] Mix 1 Synthetic Fiber Option 2 28 0.27% 4.1 [ 2.5] 160 [1.10] Mix 2 Synthetic Fiber Option 3 28 0.50% 7.6 [ 4.5] 175 [1.21] Mix 2 Steel Fiber 28 0.19% 25.1 [14.9] 225 [1.10] Mix 1 Synthetic Fiber Option 2 28 0.38% 5.8[ 3.5] 26 Pavement Design methodology with FRC Design methods and codes British Concrete Society (TR34) floors Bonded Concrete Overlay of Asphalt (BCOA) IDOT Chapter 53 (2008) BCOA (Bordelon and Roesler 2012) Pitt BCOA ME (Vandenbossche et al 2013) OptiPave 2.0 (Covarrubias et al. 2011) Short slab technology Software to select fiber performance (type/quantity) Provides recommended f150 and MOR to be used in above design methods Slide 27 Modified Strength Equations MOR = plain concrete flexural strength f150 = residual strength = effective flexural strength of FRC If you use a mix with = 1.0 MPa (for example) And your ASTM C78 testMOR = 5.0 MPa (at 28 days) Altoubat et al. (2007) Bordelon and Roesler(2012) 28 Illinois Structural Design of BCOA (2007 09) Effect of Macro fibers on Slab Thickness Design 0 1 2 3 4 5 6 1E+04 1E+05 1E+06 1E+07 ESALs R150,3 = 0% R150,3 = 15% R150,3 = 20% R150,3 = 25% 29 Bordelon et al. (2008) f150 = 0 psi f150 = 112 psi f150 = 150 psi f150 = 187 psi Residual Strength Estimator Software: FRC Overlays 31https://intrans.iastate.edu/app/uploads/2019/03/Residual Strength Estimator for FRC Overlays April 19 2019_public.xlsx Residual Strength Estimator for Fiber-Reinforced Concrete Overlays Design Input Choices Type of Overlay Road Millions of ESALS in Design Life Asphalt Pre-Condition* *refer to Tech Report to example estimates of asphalt pre-condition Desired New Concrete Thickness Remaining HMA Thickness after Milling Overlay Slab Size Desired Performance Enhancements (this will generate a higher residual strength, but not included in effective flexural strength) Plain Unreinforced Concrete Flexural Strength (MOR ) psi based on 28 day Four Point Bending (ASTM C78 or ASTM C1609) Design Suggestions/Warnings: Recommended Residual Strength (f 150) Use value within this range for the Material Specification: 125 to 175 psi (target value from ASTM C1609 test results of FRC) Effective Flexural Strength (f eff) Replace the MOR from the Pavement Design Software with this value: 650 psi Developed by Amanda Bordelon, Ph.D., P.E. and Jeffery Roesler, Ph.D., P.E. Version 1.1, April 19 2019 3 to 4.5 inches HMA remaining 6ft joint spacing basic FRC overlay Instructions: Run an overlay design software to determine the design inputs. Select design choices from the drop-down menus below to narrow down the recommended performance requirement of FRC for the proposed overlay pavement. Determine the effective flexural strength to input into overlay design software instead of design concrete flexural strength. Prepare specifications to achieve design residual strength of FRC material. Local Road/Street 0.01 to 5.0 million ESALs Fair 4.5 to 6 inch PCC thickness 550 NOTE: Actual fiber dosage rates are dependent on fiber type, fiber dimensions, concrete mixing/placement technique, cement content and fiber content or volume fraction. The intended fiber and dosage rate should be verified by ASTM C1609 test method. These recommended values are based off of previous field and laboratory testing of fibers used in concrete overlay pavements. Refer to the Tech Guide or Tech Report for more details. 0 100 200 300 400 500 600 0 0.06 0.12 Mid-span deflection (inches) MOR f150 #1 Construction Challenge Fiber Balling Batching/mixing Trial concrete mixture should be made first At < 0.5% volume fraction of fibers, typically no need to change batching/mixing Slump loss may occur. Fiber Balling may occur if: Fibers added too quickly Fiber volume too high Fibers already clumped (in delivery bags) Mixer inefficient or worn blades Mixture too stiff Concrete mixed too long after fibers added Mix sequencing fibers added to mixer before other ingredients If Mix adjustment required: Add water reducer or Paste content. 32 Pavement Joints with FRC For thinner overlays, slab sizes are reduced and more saw cut joints required. Saw cut timing and depth is critical for maintaining narrow joints and good LTE. Cut contraction joints as early as possible (after final set); may need to cut every 4 to 20 slabs to relieve early stresses If fibers appear to be pulling out or raveling joint at early sawing, wait 30 min. and try again. Transverse joints are typically cut at 1/4 of depth or at least 1 inch Longitudinal joints are typically cut at 1/3 of depth Schedule extra saws for smaller panel sizes Fibers are not a substitute for dowel bars Similar to tie bars in behavior 33No fibers Macrofiber Reinforcement Benefits: Concrete Pavements Increase in structural capacity of slab Can reduce required slab thickness for pavement/overlays Maintain crack/joint widths Non uniform (variable) support condition Tie longitudinal/transverse contraction joints Avoid slab migration Extend overlay serviceability Reduce deterioration rates after initial cracking slab deflect and displace more easily Thin concrete overlays deteriorate more rapidly under traffic Consider Macrofibers for every concrete overlay 6 in. and use 6ft panels when possible 34 Illinois (USA) Concrete Overlay Survey 19 Projects Visited (2012) King & Roesler (2014) & NCHRP 01 61 (2021) 35 Chicago, IL: Western Avenue Bus Pads (2003) Project consisted of a number of stops alongWestern Avenue (5 were surveyed) 10ft x 100ft sections, 3.3ft x 4ft joint spacing 4 in thick inlay, high fiber dosage of 7.5 to 8.5 lb/yd3 Considered a bonded/unbonded hybrid project, as the conditions of the underlying layer varied project to project Western Ave. and Iowa 2012 36 Kane County, IL: North Lorang Road (2004) 4.25 thick concrete overlay of 3 of HMA over aggregate base 4 lb/yd3 synthetic macro fibers Square 5 ft x 5 ft panels Project built to serve a quarry: average of 30 trucks/day (peak of 280/day) 2012 37 E 15 Parking Lot (2006) UIUC campus FRC UTW Project 65mm AC 8 cm Thick slab 1.2 x 1.2m Joint spacing 1.8kg/m3 or 0.2% Fibers Fly ash Asphalt Before During Paving Sawcutting Amount (lb/yd3) Coarse Agg 1903 Fine Agg 1214 Cement 428 Water 219 Fly Ash 133 Strux Fibers 3 Admixture Daracem 19 Material Final X sect 2007 McKinley Parking Lot at Univ. of Illinois 39 McKinley Parking Lot (6 years old) 2013 40 Richland County, IL: County Highway 9 (2010) 5.5 in. PCC overlay of a ? HMA surface x square panels 4 lb/yd3 structural synthetic fibers 2012 41 Hamilton County, IL (Sept. 16, 2014) FRC UTW (4-in) Existing Asphalt Concrete (3-in) Cement Treated Soil (8-in.) Natural Soil 4 lb/cy of macro fibers 42 Built in 2013 Built in 9/2014 Built in 9/2014 43 Montevideo,Uruguay (2010) Punta Arenas, Chile (2010) FRC Pavements with smaller panel sizes Uruguay (2011) Ruta 24 (Madera) Bonded Concrete Overlay of Asphalt Slab thickness = 14 cm Slab size = 1.8x1.8m Synthetic fibers = 2.5 kg/m3 Ruta 24 (2016) 1.8m x 1.8m Espesor Tráfico Año de Construcción Ruta 60 Ch Camino La Pólvora (Valparaíso), Chile 23 cm (9 in) con fibra 189.000.000 EE 2016 Fibras sintéticas 1 MPa Resistencia Residual https://www.youtube.com/watch?v=It 2vbBQokQ&t=19s Ruta 60 Ch Camino La Pólvora (Valparaíso), Chile I 72 Unbonded Concrete Overlay (2015) 6 inch concrete slab thickness Asphalt or geotextile interlayer 8 inch existing CRCP Slab sizes 1.80x1.80m 4lb/cy Macrofibers I 72 Unbonded Concrete Overlay (2020) Commercial Airport Loadings Airport Bonded Concrete Overlay Paving w/ Fibers Chicago O Hare Airport (2013) edge isolation joint FRC vs. Steel Reinforced (bars) Rockford, IL Airport Prestressed FRC Taxiway Constructed 1993 Photo: 2012 Prestressed Concrete Pavement 1200 ft Section, 7in thick FRC Commercial Concrete Floors Table 4.2 (ACI 360) Rated capacity = 2.5t to 20t 1t to 10t payload Can have payload = 30t results in thick slabs Specification Suggestions for FRC Pavements ASTM 1116 of fibers allowed Type I (ASTM A820), Type II glass (ASTM C1666), Type III synthetic (ASTM D7508), etc. Fiber geometry (diameter & length) Batching and mixing process for macro fibers in concrete Residual strength (f150) C1609 12 e.g., quantity of fiber must achieve f150=125 psi Max and min. fiber dosage (lb/cy) Fiber balling (max) & variability in f150 (min) 58 Concrete Pavements w/ Macrofibers Summary Many successful projects (parking lots, overlays, bus stops, commercial floors, airports, full depth repairs) Macrofibers increase slab capacity Many acceptable macrofibers (synthetic and steel) Residual strength test (ASTM C1609 12) is acceptable method Design tools exist now! Construction mixing and dispersion 59 Questions & Further Information Contact Speakers: Jeffery Roesler, Ph.D., P.E., University of Illinois Urbana Champaign jroesler@Illinois.edu 60 Useful Resources for Concrete Overlays NCHRP 01 61 of BCOA (2018 20) National Concrete Pavement Technology Center at Iowa State University http://www.cptechcenter.org/research/research initiatives/overlays/ Guide to Concrete Overlays (3rd edition), 2014 Guide to Concrete Overlays of Asphalt Parking Lots, 2012 Guide to Design of Concrete Overlays, 2012 Illinois Center for Transportation at the University of Illinois Urbana Champaign http://ict.illinois.edu/research/publications/ Design and Concrete Material Requirements for Ultra Thin Whitetopping, 2008 Structural Performance of Ultra Thin Whitetopping on Illinois Roadways and Parking Lots, 2014 BCOA ME at the University of Pittsburgh http://www.engineering.pitt.edu/Vandenbossche/BCOA ME/ 61 Fibers Webinar – Questions and Answers 2/9/2021 The questions submitted during the webinar follow with answers that our speakers have provided. Key fiber resources for concrete pavements available include: 1. https://intrans.iastate.edu/app/uploads/2019/04/FRC_overlays_tech_ovw_w_cvr.pdf 2. https://intrans.iastate.edu/app/uploads/2019/10/MAPbriefMarch2019.pdf 3. https://intrans.iastate.edu/app/uploads/2019/03/Residual-Strength-Estimator-for-FRC- Overlays-April-19-2019_public.xlsx 1. Do steel fibers tend to get magnetized during the batching process? Florida I have not seen literature whether the batching process magnetizes the steel fibers. Without the presence of an extremely high magnetic field and steel at elevated temperatures, there is no reason to expect magnetization of the fibers during the batching. Ironically, we have recently been testing in the lab the electromagnetic response of steel fibers in concrete, specifically their magnetic properties. We have noticed different magnetic properties based on the manufacture/type of steel fibers. Steel fibers may be somewhat magnetized during the manufacturing process especially above the Curie temperature and in the presence of a strong magnetic field 2. We had tried using steel fibers in concrete but they tended to create balls during the batching. Can you discuss any solutions? Florida Yes, this is not surprising. Most projects struggle initially with fiber balling especially as the volume fraction increases. Like any mix design adjustment when a new additive is introduced, it takes time to determine what the right adjustment should be. It could be changing the batching procedure of the fiber, it could be type of fiber is more prone to balling (higher aspect ratios), it could be rate of fiber introduction into the drum, and it could also be the paste content or slump of the mixture. This particularly topic is covered extensively in the above references since it is one of the most common questions and concerns. 3. Is there any significant chemical reactions of steel fibers in concrete pavements? Pennsylvania In general, there is no chemical reaction between steel and cement paste similar to reinforcing steel and concrete. Fibers have various shapes and textures to promote pullout resistance through mechanical means. The only reaction that fibers can have is superficial corrosion of individual fibers on the surface of the concrete, which are exposed to the elements (oxygen, water, chlorides). https://intrans.iastate.edu/app/uploads/2019/04/FRC_overlays_tech_ovw_w_cvr.pdf https://intrans.iastate.edu/app/uploads/2019/10/MAPbriefMarch2019.pdf https://intrans.iastate.edu/app/uploads/2019/03/Residual-Strength-Estimator-for-FRC-Overlays-April-19-2019_public.xlsx https://intrans.iastate.edu/app/uploads/2019/03/Residual-Strength-Estimator-for-FRC-Overlays-April-19-2019_public.xlsx 4. Are fibers more effective in concrete pavements than asphalt pavements? Pennsylvania This is a very good question and I will offer some thoughts on this. We have >40 years of experience with fiber reinforced concrete and very little experience with fibers in asphalt pavements. I believe in the past 15 years we have really improved the use of fibers in concrete in terms of design, construction, and expected behavior of a particular engineered fiber. We no longer have to base decisions on an engineer’s experience only but we have design codes, standardized testing, field performance sites, and more theoretical understanding of failure mechanisms. For asphalt, we are seeing more fibers in the market for applications and I do receive calls from engineers about how can fibers improve flexible pavements and whether the performance claims made by manufacturers are true. We know that adding macrofibers to concrete increases the cracking resistance of the plain concrete and we can take advantage of that in the design and long-term serviceability of the concrete pavement. For flexible pavements, the first set of questions would be (a) what is the purpose of the fibers? (b) what failure mechanism am I trying to alter with fibers? (c) how does the temperature and fiber properties (geometry, surface texture, tensile capacity, and elastic modulus) affect the mechanism I am targeting? In my opinion, if I was using fibers in asphalt pavement today I would need to decide if I am primarily targeting rutting, fatigue cracking, block cracking, or thermal cracking. These failure mechanisms would likely require different types of fibers (e.g., modulus, aspect ratios) and no single fiber could work for all mechanisms but I am sure some fibers are a good balance. Note, rutting occurs at higher temperatures and therefore, longer fibers with lower modulus may work better whereas for fatigue, fibers may need to be of shorter length and higher modulus. Ultimately, a hybrid mixture of fibers may be the solution for tackling rutting potential and fatigue crack development. You will have the same mixing questions with asphalt and fibers that you have for concrete and how much should I add per ton of asphalt. Furthermore, you will need appropriate performance tests to determine the right dosage for a particular design strategy. Finally, the batching and mixing temperature of asphalt can alter or be detrimental to certain polymer fibers. 5. Can methacrylate be used at a later time with macro fiber reinforced concrete pavement? Arizona I am assuming this is for sealing cracks or the surface of the concrete. I have not heard of this being an issue in the past and a quick literature review didn’t find any case studies or findings of negative reactions of methacrylate with concrete fibers. 6. How do you test the amount of fiber in FRC concrete? New Jersey See the reference documents suggested at the beginning of this response. The tech brief and full report above go into great details how to test the amount of fiber to add to improve flexural capacity of concrete slabs. ASTM C1609-12 is the most recommended standard to characterize the residual strength of FRC for pavement in US. 7. How does FRC affect concrete's permeability? New Jersey Assuming normal paving concrete without any ‘cracks’, then macrofibers should not affect the concrete’s permeability. 8. How does the cost of FRC compare with non-FRC concrete pavements? New Jersey This depends on the amount of fibers per cubic yard and specific fiber brand (type). In general, one can expect 15% to 20% increase in concrete material cost with fibers but this will vary with volume fraction and project location. 9. What is the maximum slab thickness for FRC concrete? New Jersey This would depend on the structural design of the pavement which includes the environmental conditions, load levels, and slab geometry. As shown in the presentation, FRC is used in airports where loads can be 5 to 6 times higher per wheel load than highways so there is no maximum thickness concept for FRC like for plain concrete. The thickness of a slab can be reduced with fibers, which depends on the aforementioned factors and residual strength the fibers provide to the concrete. 10. What options would you recommend that work as well as FRC? New Jersey There are multiple ways to reduce the slab thickness or increase slab performance. Fibers are one option to increase the slab flexural capacity. Short slabs with the same thickness will also increase slab capacity. Strong foundation layers can improve performance. Avoiding loads along the edge will also reduce the required slab thickness. 11. Do you recommend a minimum trial batch size to determine fiber disbursement issues? Michigan Yes, this is an excellent and possibly essential step given each mix design is somewhat unique and different fiber types have different water demands. This is recommended in the resources provided above. There are many ways to improve disbursement of fibers such as better batching techniques, chemical admixtures, etc., but project engineer/contractor must determine what works best for a particular project, materials, and ready-mix supplier. A trial batch is an essential part to a successful project to avoid large volume of FRC at the job site with inadequate fiber distribution. There is no universal mix design for FRC given the project objectives determine the mix workability and needs for constructability. 12. How deep are the joints? Quebec Joints need to be cut as deep as traditional plain concrete and as soon as possible to avoid the concrete gaining too much tensile strength and being more resistance to crack propagation at the contraction joints. Late sawing may not produce random cracks in the slab but could produce more dominant joints that open very wide given some contraction may not actually crack. This has been seen in the field before especially for larger panel sizes. 13. How are the fibers loaded into the central mix drum? Do they manually dump pre- weighed bags on the main conveyor or is it automated? Pennsylvania This depends on the type of fiber and how the manufacturer packages the fibers. There is no one-way to introduce the fibers and ready mix producers and contractors must work with fiber suppliers for best practices. Some fibers come in water soluble bags that can be added on the conveyor belt to the drum. Some fibers can be augured into the drum, and other systems can blow fibers into the drum. The same principles go for transit mixing trucks which require some experience on best way to introduce and achieve disbursement. 14. What is the cost per cy for a typical 4 lb. dosage? Pennsylvania This will depend on the fiber brand (quality), location (shipping), and volume supplied for a project but an estimate could be $3 to $5/lb. 15. Why has ACI 330 not adopted this methodology for incorporating fibers into thickness design? Or perhaps ACPA? Colorado I am not exactly sure why ACI 330 has not incorporated this yet into their design recommendations but I am not engaged in that committee to know the details. I know engineers on this committee and I know they are aware of how to do and have even implemented these design concepts with fibers in other software. For example, there is design software for exterior slabs utilize these concepts for FRC design (e.g., Opti- Pave 2.0 and discontinued program called BCOA by ACPA). I actually assisted ACPA in implementing this into their BCOA App store approximately 10 years ago with Robert Rodden. It has subsequently been added to Pitt BCOA-ME and ACPA Pavement Designer allows certain concrete pavement designs to be made with fibers. 16. Should I use non-shrink admixture in addition to fibers in order to decrease possibility of shrinkage cracking? Maryland You can do this especially if your objective is to design extended joint slab systems. For normal joint spacing with fibers or even short-jointed slabs used for concrete overlays such as BCOA or unbonded systems, very low shrinkage mixtures can prevent regularly spaced contraction joint activation. There are other reasons to design lower shrinkage such as reduced curling and debonding if it is a bonded overlay. Shrinkage reducing admixtures may be added for similar cost to a mixture as macrofiber so it must make economic sense for the design to combined fibers + shrinkage reducing admixture. 17. Do you experience any corrosion with steel fibers? Illinois In general, corrosion of steel fibers has not been a significant issue even though it is a very common question that I receive during presentations. Steel fibers have been successfully applied on industrial and airports pavement projects for 30 years without major reports of corrosion. There are no large continuous circuits setup with small discrete fibers so if corrosion does occur it is very localized (unlike steel reinforcing bars). I have seen a few projects where the fibers on the very top of the surface over time corrode individually and pop out, which at worse just looks bad but no structural issues. If there are high chlorides at wider joints and it is the main mechanism for load transfer then there may be instances of corrosion causing loss in joint capacity (not much of this reported). Given there are not huge number of FRC pavements for roads (with steel fibers) that have been reviewed on a regular basis, this issue does not seem to have evidence of being an issue with any frequency. In my experience, the vast majority of steel fibers are typically applied to interior slab systems where corrosion is not an issue at all. 18. Slide 32 notes an increase in paste content if mix adjustment is needed. Could an increase in mortar content, not just paste content, be as beneficial so increasing cement is not necessarily required? South Carolina Yes this is a possible suggestion that could work but it would depend on the type of sand, coarse aggregate, and combined gradation and the existing volume of paste in the mix. 19. What is the approximate cost of adding fibers to the mix? Iowa This depends on the pavement application but 15% to 20% for typical concrete pavement applications. 20. Do the fibers effect the surface finish? Arkansas Macrofibers can affect the surface finish to a degree and it depends on the type of fibers and application. Floor slabs are power troweled which produces a very smooth surface without seeing the fibers. For pavements, tining and texturing can cause some of the fibers to protrude from the surface. These fibers wear-off pretty quickly under traffic and UV radiation especially for polymeric. Manufacturers have specifically designed lower flexural modulus fibers with the express purpose of better finishing if appearance is of key importance. 21. Do the fibers still allow a crack to develop at contraction joints? Arkansas Fiber joints do activate but they may be delayed depending on the joint spacing chosen and restraint offered by base friction coupled with the magnitude of temperature/moisture contraction. Additionally, FRC joint sawcuts must be at least similar depth to plain concrete and more care should be used in cutting joints as soon as possible to increase the probability that the joints activate early versus later when the concrete gains strength and fibers offer high resistance to crack propagation at the joint. 22. When designing with Macro-Fibers in Spec. commercial world, we typically have to get the "powder content" around 600#, does the extra powder offset itself with the fiber in regards to shrinkage? Pennsylvania This is difficult to answer exactly and not sure if I am answering Mark’s question. Exterior pavements don’t undergo the same magnitude of moisture curling that indoor slabs suffer at times where shrinkage can be a major problem in flatness and joint performance. Moisture curling can be a problem in exterior pavement and shrinkage can be an issue but most mixtures for pavements have total cementitious of 500 to 575 lb/cy. Additionally, most pavements are slip-formed whereas commercial floors are typically pumped with a higher slump. Sufficient paste or powder content is one factor for a successful mixture but gradation of the aggregates and types of aggregate will also impact the required cementitious content, water, and any further admixtures. Adding too much powder to achieve workability may produce unacceptable shrinkage for a project requirement. 23. Does fiber-balling look similar with synthetic vs. steel fibers, i.e. do synthetic and steel fibers have the same probability to develop balling, or does one seem to mix and separate better than the other? Illinois I am not sure the probability differences but both can ball up if fibers are not charged to the mixing drum at proper time; if mix design is too dry; or insufficient energy is used to mix the concrete. In my experience, synthetic fibers have produced smaller fiber balls of several inches whereas I have seen much large fiber balls with steel fibers, e.g., > 6 inches. Note, balling also depends on type of fiber, its aspect ratio, and how it is packaged. 24. What is the thinnest concrete overlay? Any special type of concrete needed with, say1/2 in thick overlay? Indiana The thinnest concrete pavement overlay I am aware of is 5 cm or 2 inches. This is very uncommon but possible. 25. Joints seem to be on top of wheel path in slide 59. Did you see any distresses because of this? Texas This slide has 6ft panels which is the best size to use for short-jointed slabs and keeps the wheel path (1.5 to 2 ft off slab edge) of any longitudinal joint. Slab sizes of 4 ft panels will more easily have wheel paths over one of the longitudinal joints especially the inside axle. These slab sizes have shown to create premature failures with heavy axle loads, poor surface drainage, and higher pavement deflections. 26. Please let me know how to access long-term performance data if you have it. Texas There a few studies on longer term performance of FRC overlays (See reference reports which were written with this in mind. See also King and Roesler 2013, Gross et al 2017, and NCHRP 1-61 to be published in March 2021, which has performance review). You can also access the National Concrete Overlay explorer which has a list of projects with fibers. 27. Have you used human hair as fiber reinforced concrete? Human hair is strong in tension, non-degradable and is available in abundance. Have you done any research or any information? California There are multiple issues with use of human hair fibers. The main issue with human hair is its aspect ratio, which is extremely high. High aspect ratios will have significant fiber balling problems which cannot be resolved unless a very small volume fraction is added. Typically for macrofibers, the aspect ratio needs to be around 60 to 90 for most pavement applications. The performance of fibers is also much more than just the tensile capacity of the fiber and long fibers which bond to concrete will fracture even with high tensile capacity. For example, use of carbon fibers of high aspect ratio or Kevlar have not been successful for pavement applications because of high aspect ratio available which leads to severe fiber balling and fracture during crack growth. 28. We had a thin overlay with fibers a few years ago - we experienced some minor delamination & spalling. I assume due to mix not being uniformly distributed. Fiber balling? Indiana I am not sure what type of overlay this was (bonded or unbonded on asphalt or concrete?). Fiber balling issues would pretty noticeable in the field survey if it was causing distress since you would see the clumps of fibers either embedded in concrete causing spalling or on surface. Fiber balling is one of the key issues seen in construction problems and just needs careful attention by contractor and field engineer to make sure process is in place for adequate disbursement. Engineers can’t assume by adding 4lb/cy of macrofibers to a typically good mix without any process changes that this will produce a well distributed fiber system. 29. Comment: Michigan DOT's new detail for edge drain outlets will now be a cast-in- place 4-inch thick slab, 3' x 3' min., with 4 lb/cyd macrosynthetic fibers. Old standard is a precast bullet / end section. Michigan Sounds like a great idea and application. I know precast companies have been using macrofibers for >10 years for septic tanks, pipes, burial vaults, etc. quite successfully and this is a great application for macrofibers. 30. Is there design criteria for adding fibers to cement treated soil? Washington This is a good question and there is a benefit but more work is needed in this area (See example paper by LaHucik et al. 2016, Cement-Treated Bases Containing Reclaimed Asphalt Pavement, Quarry By-Products, and Fibers). There are other papers on benefits of fibers with different types of soils especially sands. 31. Your focus has been on using fibers to increase slab capacity, what about their use to enhance joint load transfer? Can they replace dowel bars? Minnesota There have been a few studies on effect of fibers on load transfer as you know. This is covered in the summary report provided at the beginning of this document. In general, there is not sufficient evidence, in my opinion, to change the pavement design because of fibers effects on concrete contraction joints. There is a small increase in load transfer with macrofibers and decrease in the rate of deterioration of fiber reinforced concrete contraction joint based on the few studies. However, I don’t believe there is sufficient performance evidence or research to replace dowel bars with macrofibers. At this point, fibers can be linked more closely with tie bars, i.e., keep cracks tight, which indirectly improves aggregate interlock. Fibers don’t offer the bending and shear resistance that dowel bars provide. 32. Wearing surface as it relates to skid resistance? Missouri I am not aware of increased friction properties for macrofibers and would not expect increased friction. Several studies have shown increased abrasion resistance particularly with steel fiber addition for concrete slabs on grade as well as other concrete products with steel fibers. 33. Did you find the relationship between energy for dispersion of fibers with different L/D and in different dosages of fibers for different paste amount and W/C in concrete? Iran I have not personally done testing like this, and I am not sure if the literature has a specific study like this. I expect that there will be a dispersion energy relationship like this for fiber L/D, fiber volume fraction, paste viscosity, and paste volume. Fibers Webinar – Questions and Answers 2/9/2021 | |
| Subgrades and Subbases: Iowa DOT Research and Next Steps | 👤 Melissa Serio | Concrete Lunch & Learn | Winter 2020–2021 |
| 2021-01-28 | Center for Earthworks Engineering Research Subgrades & Subbases: Iowa DOT Research and Next Steps VIC APLT E-Construction Center for Earthworks Engineering Research Outline • Overview of challenge facing the DOT • Background & results of research projects – STIC project – AID project • Overview of DOT Implementation Plan • Closing comments and questions Center for Earthworks Engineering Research Challenge facing the DOT • The primary system includes 24,534 lane miles of pavement. • Value to replace is over $14 billion • Half of the system’s original pavement is more than 55 years old. • 29% (6,792 miles) is 70+ years old Center for Earthworks Engineering Research Challenge facing the DOT • Current situation with funding. • Need to extend pavement life. • How? • Improve material performance • Improve foundations • Continually improve construction quality Center for Earthworks Engineering Research Research Projects • 2017 & 2018, STIC (State Transportation Innovation Council) Incentive Program: $100k • 2019 & 2020, AID (Accelerated Innovation Deployment) Demonstration Program: $700k Center for Earthworks Engineering Research IOWA STATE UNIVERSITY Civil, Construction & Environmental Engineering Center for Earthworks Engineering Research Roller Mapping of Modulus Center for Earthworks Engineering Research Different typical foundation layer support conditions were evaluated at the 10 project sites. Project 1 Project 2 Project 3 Project 4 Project 5 Project 6 Project 7 Project 8 Project 9 Project 10 Granular Subbase – Cr. Limestone Granular Subbase – Recycled PCC Modified Subbase – Cr. Limestone Modified Subbase – Recycled PCC Select Subgrade Special Backfill – Recycled Asphalt 8.4 to 10.9 in. 9.7 to 11.0 in. 10.0 to 11.1 in. 23.4 to 24.0 in. 24 in. 24 in. 24 in. Embankment Cut/Fill 24 in. 24 in. 24 in. 12 in. 24 in. 7.5 to 9.6 in. 6.0 to 10.3 in. 6.0 in. 24 in. 21 to 23 in. Project 1 Project 2 Project 3 Project 4 Project 5 Project 6 Project 7 Project 8 Project 9 Project 10 Granular Subbase – Cr. Limestone Granular Subbase – Recycled PCC Modified Subbase – Cr. Limestone Modified Subbase – Recycled PCC Select Subgrade Special Backfill – Recycled Asphalt 8.4 to 10.9 in. 9.7 to 11.0 in. 10.0 to 11.1 in. 23.4 to 24.0 in. 24 in. 24 in. 24 in. Embankment Cut/Fill 24 in. 24 in. 24 in. 12 in. 24 in. 7.5 to 9.6 in. 6.0 to 10.3 in. 6.0 in. 24 in. 21 to 23 in. Center for Earthworks Engineering Research 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 A v e ra g e D e fo rm a ti o n , d (i n .) Applied Stress (psi) k = 284 pci k = 39 pci k = 150 pci Design Target Modulus is the most critical foundation input parameter in pavement design, and field verification of this value is important! Test Results from I-80, Polk County 12 in. Modified Subbase over Select Subgrade Center for Earthworks Engineering Research KEY Outcomes of this project are: Mr values are variable across the state and within each project site. Cv between 5% and 80% at each site. k-values across the site varied between 35 and 300 pci. 11 out of 14 tests showed < 150 pci. Sites with 2 ft of special backfill material provided higher Mr values than other sites. Typical values provided in the ME Design Guide based on soil classification are not reliable. Center for Earthworks Engineering Research KEY Outcomes of this project are: K values over granular or modified were lower than those directly on underlying subgrade material. dp from static PLT varied between 0.05 and 0.4 in., with 11 out of the 14 tests > 0.05 in. critical limit. FE analysis showed that the two most important factors to reduce bending stresses in the pavement layer are pavement thickness and dp . Center for Earthworks Engineering Research AID Project Objectives • Continuation of APLT testing and incorporation of VIC technology • Understand results obtained from current requirements – Measure modulus of foundation layers that are built with current specification requirements • Shadow test with VIC and APLT technology Center for Earthworks Engineering Research AID Project Objectives, Cont. • Develop e-Construction system that allows near real time use of data • Develop Implementation Plan – Identify improvements to current specifications (materials and construction requirements) – Identify changes to current pavement design procedures Center for Earthworks Engineering Research AID TWG Members Iowa DOT • Newman Abuissa • Ben Behnami • Chris Brakke • Vanessa Goetz • John Hart • David Heer • Dean Herbst • Hugh Holak • Stephen Megivern • Kevin Merryman • Brian Moore • Wes Musgrove • Jeffrey Schmitt • Melissa Serio • Dustin Skogerboe Industry Stakeholders • Dan King (ICPA) • Ryan Kipp (CJ Moyna) • Adam Kos (CJ Moyna) • Brian Manatt (Manatts) • Greg Mulder (ICPA) • Ron Otto (AGC Iowa) • Cork Peterson (PCI US) • Scott Dockstader (APAI) • Steve Streb (Streb Construction) • Tim Tometich (Manatts) FHWA • Micah Loesch • Lisa McDaniel Academia • Prof. Bora Cetin (Michigan State University) Ingios • Tom Cackler • Bruce Cunningham • Brendan Fitzpatrick • Kera Gieselman • LaDon Jones • Craig Swanson • Colby VanNimwegen • Pavana Vennapusa • David White Center for Earthworks Engineering Research 2019 2020 Center for Earthworks Engineering Research 2019-2020 Scope for Mapping Verification 2020: No. of Projects Sites: 9 No. of Maps Performed: 134 No. of APLT Performed: 78 2019: No. of Projects Sites: 6 No. of Maps Performed: 38 No. of APLT Performed: 59 Center for Earthworks Engineering Research GPS Run Data Data is processed by COMP-Score Pro 3D to create maps & application data COMP-Score CONNECT E-construction Data Flow & Processing Center for Earthworks Engineering Research COMP-Score calibration of k-values on-site provides high confidence in the modulus mapping outputs. 50 75 100 125 150 175 200 225 50 75 100 125 150 175 200 225 A c tu a l V IC -k u 1 [p s i/ in .] Pred. VIC-ku1 [psi/in.] Linear Fit 90% Prediction Limits 90% Confidence Intervals 50 100 150 200 250 300 50 100 150 200 250 300 A c tu a l V IC -k u 1 [p s i/ in .] Pred. VIC-ku1 [psi/in.] Linear Fit 90% Prediction Limits 90% Confidence Intervals Regression Statistics N 9 R² 0.998 R²(adj.) 0.996 RMSE 4.0 Regression Statistics N 14 R² 0.944 R² adjusted 0.927 RMSE 9.1 Subbase/Special Backfill Select Subgrade Center for Earthworks Engineering Research Blackhawk County, US20 Project (08/27/2019) Special Backfill Granular Subbase Center for Earthworks Engineering Research IOWA STATE UNIVERSITY Civil, Construction & Environmental Engineering Hamilton County, I35/Hwy175 Ramps Select Subgrade (TOP) and Modified Subbase (BOTTOM) Center for Earthworks Engineering Research Hamilton County, I35/Hwy175 (09/03/2019) Special Backfill Modified Subbase Subgrade Center for Earthworks Engineering Research Jasper County, I-80 (06/18/2020) 24 in. Subgrade Treatment Modified Subbase 24 in. Subgrade Treatment Special Backfill Subgrade Geogrid Subgrade (No treatment) Subgrade Treatment 24 in. Subgrade Treatment Modified Subbase 24 in. Subgrade Treatment Special Backfill Subgrade Geogrid Center for Earthworks Engineering Research Jasper County, I-80 (06/18/2020) 0.0 6.0 12.0 18.0 24.0 30.0 36.0 0.1 1.0 10.0 100.0 D e p th ( in c h e s ) California Bearing Ratio, CBR (%) PT3 PT1 PT3 PT1 24 in. Subgrade Treatment Modified Subbase 24 in. Subgrade Treatment Special Backfill Subgrade Geogrid Center for Earthworks Engineering Research Blackhawk County, US20 (09/05/2019) – Modified Subbase Delta k-value Map Center for Earthworks Engineering Research Reliability, R = 95% St. Dev., So = 0.29 PCC Layer Thickness, D = 11 in. Elastic Modulus of PCC, Ec = 5 million psi Initial Serviceability Index, po = 4.2 Terminal Serviceability Index, pt = 2.5 Joint Coefficient, J = 3.2 Coefficient of drainage, Cd = 1.25 Modulus of Rupture, Sc = 600 psi Design Life = 40 years Design ESALs = 21.8 million Loss of Support, LOS = 0 Design Life – delta (No LOS) Blackhawk County, US20 (09/05/2019) – Modified Subbase Delta Design Life Map 1 Center for Earthworks Engineering Research Design Life – delta (LOS = 2) Blackhawk County, US20 (09/05/2019) – Modified Subbase Reliability, R = 95% St. Dev., So = 0.29 PCC Layer Thickness, D = 11 in. Elastic Modulus of PCC, Ec = 5 million psi Initial Serviceability Index, po = 4.2 Terminal Serviceability Index, pt = 2.5 Joint Coefficient, J = 3.2 Coefficient of drainage, Cd = 1.25 Modulus of Rupture, Sc = 600 psi Design Life = 40 years Design ESALs = 21.8 million Loss of Support, LOS = 2 Delta Design Life Map 2 Center for Earthworks Engineering Research Des Moines County, US61 (10/23/2019 – FALL) Select Subgrade Center for Earthworks Engineering Research Des Moines County, US61 (05/16/2020 – Spring) Select Subgrade Center for Earthworks Engineering Research IOWA STATE UNIVERSITY Civil, Construction & Environmental Engineering Dubuque County, US52 Modified Subbase Center for Earthworks Engineering Research Compacted Subgrade (No Cement Modification) PT4 PT3 Dubuque County, US52 (08/12/2020) – Cement Modified Subgrade 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 A v e ra g e D e fo rm a ti o n ( in .) Applied Stress (psi) Center for Earthworks Engineering Research US61, Des Moines County (06/16/2020) Granular Subbase – Crushed Limestone How does current compaction specification on Granular Subbase affect Drainage Vs. Stiffness Center for Earthworks Engineering Research Summary of Vu Meter Test Results from multiple project sites 4 7 2 3 2 1 3 1 1 2 3 2 2 2 1 10 100 1000 US61, Des Moines County [Crushed Limestone] US30, Tama County [Crushed Limestone] US13, Linn County [Recycled Concrete] US52, Dubuque County [Mixture of Recycled PCC & RAP] US20, Dubuque County [Crushed Limestone] V u M e te r - A v e ra g e T im e f o r D ra in a g e ( s e c ) 1 to 5 Passes 8 Passes 12 to 24 Passes Number on each bar represents the number of tests GRANULAR SUBBASE (4121) MODIFIED SUBBASE (4123) 30 to 120 seconds for "Good" drainage (per, John Hart, PCC Field Engineer, Iowa DOT) Center for Earthworks Engineering Research Secondary Roads Evaluation using COMP- ScoreTM RT Segments Mapped ~21 miles Center for Earthworks Engineering Research Mapping Length: 21 miles Mapping Duration: 6 hours Number of Data Points: 38,729 Center for Earthworks Engineering Research 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 R e s il ie n t M o d u lu s ( p s i) Distance (miles) U S3 0/ W A ve . W A ve ./ 34 0t h St . X A ve ./ 34 0t h S t. H w y E6 6/ X A ve . R ai l R o ad S o u th o f H w y E6 6 38 0 th S t. /X A ve . B ri d ge o n 3 80 th S t. 38 0t h S t. /W A ve . 39 0t h S t. /W A ve . 39 0t h S t. /U U A ve ./ 38 0t h S t. 38 0t h S t. /T A ve . T A ve ./ 38 5t h S t. 38 5t h St ./ S A ve S A ve ./ 40 0t h S t. T A ve ./ 40 0t h S t. T A ve ./ 38 5t h S t. U A ve ./ U U A ve . U U A ve ./ 38 0t h St . Analysis underway to assess % of roadway needing repair, with options for repair (remove/replace or thicker gravel layer or stabilization options) Reference Target Composite Modulus Value [9,000 psi] Center for Earthworks Engineering Research Compaction reports are a key component of what COMP-Score™ CONNECT delivers. A Modulus Map displays performance of compaction quality across 100% of the area measured. Center for Earthworks Engineering Research Compaction reports are a key component of what COMP-Score™ CONNECT delivers. Quality analysis metrics give the viewer a quick glance at how the mapping performed against established targets. Center for Earthworks Engineering Research Pilot Projects - 2021 • Boone County, IA 17 – Grading – Approx. 0.5 miles N. of US 30 north and east approx. 3 miles – January 20, 2021 letting • Black Hawk County, US 20 – PCC Pavement – Replace – US 63 to IA 21 in Waterloo (EB / WB) – February 16, 2021 letting Center for Earthworks Engineering Research Pilot Projects - 2021 • Special Provision: Modulus Verification Using Roller Mapping of Pavement Foundation Layers – Equipment Requirements – Training Requirements – Mapping Requirements – MOM & BOP Center for Earthworks Engineering Research Overview of Implementation Plan • 5 Year Plan (2021 – 2025) to transition from pilot projects to full implementation • Plan is to have each RCE Office get project experience • DOT considering having Ingios map completed grading projects in 2021 to support development of paving plans. • Potential for county applications developed parallel with DOT implementation Center for Earthworks Engineering Research Overview of Implementation Plan Anticipated DOT Project Applications • 2021 - 2 projects • 2022 - 5 projects • 2023 – ~10 projects • 2024 – ~20 projects • 2025 – Statewide implementation as standard Center for Earthworks Engineering Research Overview of Implementation Plan • Develop SPs for use in future years • Develop training program to possibly integrate into DOT existing web-based curriculum • Develop LCCA models • Identify other DOTs interested in technology partnership Center for Earthworks Engineering Research Closing Comments • Additional questions/discussion? • Thank you for attending! Melissa Serio Earthwork Field Engineer Construction & Materials Bureau, Iowa DOT Melissa.serio@iowadot.us Ph. 515/239-1280 mailto:Melissa.serio@iowadot.us | |
| Dowel Bar Retrofit (DBR) and Diamond Grinding Best Practices | 👤 John Roberts 👤 Joe Echelle | Concrete Pavement Technology Tuesday Webinar | 2021 |
| 2021-01-12 | Dowel Bar Retrofit and Diamond Grinding Best Practices John Roberts Executive Director International Grooving & Grinding Association January 12, 2021 Pavement Preservation Philosophy Keeping good roads in Good Condition! PCCP Preservation Techniques Subsurface rehabilitation Partial-depth repair Cross-stitching longitudinal cracks/joints Dowel bar retrofit (AKA Load Transfer Restoration) Full-depth repair Diamond grinding Joint & crack resealing Dowel Bar Retrofit (DBR) Purpose of Dowel Bar Retrofit Reestablish load-transfer across joints or cracks Load-transfer is a part of its load to its neighboring slab Used in JRC and JPC pavements to limit future faulting Load Transfer = 100% (Good) L= x U= 0 Load Transfer = 0% (Poor) L= x U= x Where is DBR Utilized Interstate Highways Secondary Roads County Roads City Streets Industrial Facilities Joint Faulting DBR Used to Fix Transverse Crack WSDOT DBR Research Since 1992, WSDOT has retrofitted well over 300 Lane-mi in excess of 700,000 bars Average age of pavement prior to DBR was 32 yrs. DBR provides superior performance providing in excess of 20 years additional life Many 30 and 40 year PCCPs successfully retrofitted for additional pavement life at a fraction of the cost of reconstruction Pavement Age vs. DBR Placement IGGA DBR Project Database Includes individual project data including: Project Location Project Date Number of bars installed Over 7.5 million bars installed in the US since 1992 DBR Usage in the USA International Grooving and Grinding Association 12 Dowel Bar Retrofit Operations Consists of 4 main operations: 1. Cutting the slots 2. Preparing the slots 3. Preparing and placing the dowel bars 4. Backfilling the slots Cutting the Slots Diamond saw slot cutter Cuts multiple slots in a single pass. Cuts form the edges of the slots Fins are removed later Saws cut between 3 to 8 slots in a single pass Dowel Slot Alignment Correctly Aligned Dowel Slots Incorrectly Aligned Dowel Slots Centerline Must always be parallel to centerline Must be cut so at least one-half of dowel can be on each side of the joint or crack Misaligned Slots Proper Alignment is Critical Joint Contraction Joint Expansion Slot Creation Slot Cutting with Milling Machine International Grooving and Grinding Association 21 Retrofitted Dowel Bar Varies END VIEW As required Compressible insert EndcapChair Joint or crack Mid-depth of slab SIDE VIEW Fig. 8.3 on p. 8.7 International Grooving and Grinding Association 23 Removing the Concrete Fins Use 15 to 30 lb pneumatic hammers Chip out in large pieces Pop with hammer at end of fin Pop with hammer along saw cut Flattening the Slot Bottom Remove burrs and bumps from base with small bush hammer Allows the dowel to sit level and properly aligned. Cleaning and Caulking the Slots Slot cleanliness is essential Sandblast (Waterblast) first Remove debris with compressed air Check for dust with hand Caulk the joint / crack within the slot Caulk bottom and sides Prevents patch material from entering joint or crack Sand/Water Blasting Caulking the Slots Dowel Bar Requirements Typical bar diameter: 1.5 inches Minimum length: 15 inches Need at least 6 inches on each side of the joint or crack Epoxy Coated Lubricated with some type of bond breaker Preparing the Dowels Add joint former Styrofoam Fiber board Attach non-metallic expansion caps Attach non-metallic chairs (sized for slot) Placing the Dowels Ensure that legs of chairs fit tightly against slot walls Push assembly to base of slot Center reformer on the joint or crack Plan and side view of inserted dowel Joint/Crack 2 3/8 2 5/8 in Slot Width 18 in Dowel 1 ½ in dia. Expansion Cap Chair Joint Reformer Mid-depth Backfill Materials Basic requirement Thermal properties be similar to concrete. Must bond to the existing concrete Should be fast setting Should have little or no shrinkage Must consistently develop enough strength to allow traffic on it in a short time. Only use materials designed for the rigors of DBR Check www.IGGA.net for recommended materials Backfill Placement Repair Material Finishing International Grooving and Grinding Association 36 Seal The Joints! International Grooving and Grinding Association 37 But only after diamond grinding! DBR Followed by Diamond Grinding Diamond Grinding Increasingly Specifiers are utilizing diamond saw cut surface textures to reduce roughness, reduce noise and increase friction on pavements, bridges and runways. Advantages of Saw-Cut Textures Costs are competitive and stable over time; Enhances smoothness, surface friction and safety Can be accomplished during off-peak hours with short lane closures Texturing of one lane does not require grinding of the adjacent lane Does not affect overhead clearances underneath bridges, signs or tunnels Blends patching and other surface irregularities into a consistent, identical surface Pavement Problems Addressed Faulting at joints and cracks Built-in or construction roughness Polished concrete surface Wheel-path rutting Permanent upward slab warping Inadequate transverse slope Unacceptable noise level What is Diamond Grinding? Removal of thin surface layer of pavement using closely spaced diamond saw blades Results in smooth, level pavement surface Provides a longitudinal texture with desirable friction and low noise characteristics Blades and Spacers Saw Blade Segment Saw Blade Core 0.105 (2.7 mm) Spacer 0.110 (2.8 mm) 0.125 0.125 (3.2 mm ) Typical Conventional Diamond Grinding (CDG) Blade Configuration Land Area 0.090 (2.3 mm) Diamond Grinding Equipment Conventional Diamond Ground Surface Purpose of Blade Spacers Spacers are Used to Separate the Cutting Blades to Allow for Cooling of the Blade and Removal of Cutting Debris They also stabilize the blades Spacer width determines the land area and controls unwanted fin development 60 Blades vs 52 Blades per Foot International Grooving and Grinding Association 48 Aggregate Hardness Map International Grooving and Grinding Association 49 Impact vs Abrasion International Grooving and Grinding Association 50 Uniform Repeatable Texture International Grooving and Grinding Association 51 Milled Surfaces Diamond impregnated carbide milling heads ARE NOT a substitute for diamond grinding. It is still simply roto-milling and an impact process! Diamond Grinding can provide a significant improvement over the pre-grind profile! I - 635 WB Lanes K1, K2 K3 & K4 152 61 0 50 100 150 200 250 Before Average Average After Average Average Before Grinding 698 Bumps After Grinding 29 Bumps Before Grinding After Grinding Safety, Surface Texture and Friction Increased macro-texture of diamond ground pavement surface provides for improved drainage of water at tire-pavement interface Longitudinal texture provides directional stability and reduces hydroplaning (side-force friction). between tire and pavement surface In Wisconsin, overall accident rates for ground surfaces were 40% less than for un-ground surfaces over a 6-year period, 57% in wet weather conditions Unacceptable Noise Level NCPTC Noise Catalogue Research conducted by the National Concrete Pavement Technology Center shows diamond grinding as the most quiet PCCP surface texture commonly used. DBR Followed by Diamond Grinding Factors For Success Using DBR & DG Selection of proper candidate projects and contractors Proper dowel design and layout Cutting and preparation of dowel bar slots Proper placement of dowels Selection of appropriate backfill material Careful material placement and curing Clear and concise expectations and specifications for DG Proper grinding equipment and qualified operators Appropriate blade spacing Knowledgeable inspection and clear communication International Grooving and Grinding Association 58 Visit Us on the Web International Grooving and Grinding Association at igga.net 59 DBR Webinar – Questions and Answers (1/12/21) The questions submitted during the webinar follow with answers that our speakers have provided. 1. Any specific material for the caulking process? JR – No the materials used in the caulking process vary from state to state and specification to specification. Some states require silicon caulk while others will allow the use of spackling compound. The key is to ensure that the gap is filled without placing the material so wide beyond the joint reservoir that it reduces bonding surface for the concrete backfill. 2. Are all dowels placed at mid-depth of the slab? What is the typical spacing of dowels? JR – The typical configuration of the dowels by most Agencies places the bar at mid depth of the slab, spaced at 12 inches on center. The outer bars are spaced at least 12 inches from pavement edge and perhaps more from the centerline joint to ensure no contact with tie steel. That said research has shown that placing the bar somewhat higher than mid depth does not negatively impact the load transfer efficiency of the DBR. See the following report. Performance Testing of Experimental DBR D 3. Can DBR be completed 'over' the existing dowel bars? JR – No. If you have faulting on a slab that already has mechanical load transfer (dowel bars), you need to do a thorough investigation to see why and how much dowel bar socketing is taking place. It is likely caused by a poor base, undersized dowels, corroded dowels or weak concrete. Some states have in the past placed DBRs in between existing bars with some success but in cases like this it is likely that a full depth repair in these locations is a better investment of one’s money. 4. Can we place the expansion cap on only one side? Why do we need the cap on both sides? JR – Yes you can but having the cap on both sides provides insurance with little cost. Additionally, the cap and chair assembly typically come as a set from the manufacturer and it only takes a second to install and therefore it has become a common practice. 5. Can you achieve success with diamond grinding only the dowel bar retrofit areas not not the entire length of the slab? JR – Theoretically yes but the dollar cost benefit typically does not favor this approach. Feathering in and out of an area takes time and expertise, whereas a continuous grind allows the operator to set into the cut and obtain maximum speed down the roadway only requiring minimal adjustment now and again making the sq yd cost much cheaper. Additionally, the driving public will better appreciate the ride, aesthetic and tonal aspects of a continuous grind far more than a “patch-work quilt” approach. JE - Our spec allows a max of 5/8” of grinding. The grinders on our projects do have some areas that are missed since the high spots would need to be ground more than 5/8”. We’ve had some areas where the panels were curled and only the middle was ground. 6. Can you provide a definition for fins? JR – Fins are the unwanted slivers of concrete that fail to break off at the desired level following the grinding process, typically due to a blade spacing that is too wide. 7. Difference in modulus between the patch material will cause stresses at the border area of the two materials. How much of a concern is matching up the modulus of the two materials? JR – It is important to pay attention to the modulus of the two materials to ensure a good bond and minimal cracking within the DBR section. Using aggregates from similar sources and proprietary backfill materials that minimize shrinkage are always recommended. 8. Do the costs of $600k/4-lane mile for DBR include diamond grinding costs? JE - Yes the cost we (Oklahoma Turnpike Authority) included the cost of DBR, Grinding, Striping, Mobilization, panel stitching for cracked panels, and some panel replacement. 9. For Joe, Do you turn the pavement back to traffic after the DBR, but before the Diamond Grinding? If so, what strength (psi) does the patching material reach before turning the traffic onto pavement? JE - Yes, we do allow traffic to drive on the DBR prior to grinding. Since the lane closures are long some of the DBR will have been placed for weeks. We use 3,000 psi as our allowed strength to open to traffic. 10. For OTA DBR propects what is rough breakdown between joint repair versus crack repair? JE - A rough estimate is that only 2% of the dowels used were for cracks. 11. Have there been any smoothness grinds done without DBR to see if the panels stay in place after all those years have passed; to see if they are even needed? We are seeing DBR filler material that is spalling out and leaving voids for moisture to do it's damage as the seasons change. JR – DBR is almost always accompanied by diamond grinding. This is done to remove any faulting, thereby reducing the dynamic loading and increasing the life of the repair. Additionally, The Washington State DOT found through extensive research that DBR projects that didn’t include diamond grinding did not perform nearly as well as those that did include grinding. If you have spalling of the DBR materials, that is likely a material or installation issue, assuming that the candidate slabs were in reasonably good condition to begin with. There is a point where DBR is NOT a good investment if the candidate slab is too far gone. There are ways to patch spalled DBRs. Please contact IGGA @ jroberts@igga.net for further assistance. JE - Yes. In the late 90’s the Oklahoma Turnpike Authority did some grinding of faulted panels at the worst locations on our network. The ride was significantly improved immediately but within months the faulting was back and after 5 years the ride was not significantly improved from its condition prior to grinding. We’ve had some areas where DBR was done 10-15 years ago and a small number of failed mortar ‘pop outs’ have occurred. Our maintenance personnel do spot repairs on those isolated areas every couple of years. We also seal all joints and cracks with maintenance personnel. 12. Are there any extra considerations for doing these treatments in cold weather? JR – Cold weather applications of DBR are typically driven by the ability to cut the slots without the cooling water freezing and the backfill material manufacturers recommendations. Diamond grinding requires temps above freezing and rising. Most specifications have cold weather cut-offs cited within. 13. How deep are the slots into the pavement? JR – The slots are typically cut to a depth that allows the bar to be placed at mid slab with room beneath the bar for backfill material consolidation. 14. How deep is the grind or removal in the left picture on the Cimmarron project? JE - Our spec is not more than 5/8” of grind. We do not require that the entire panel be ground. 15. How do you determine the appropriate pattern for each crack/joint? We saw a "three bar pattern" in the wheel paths but are there other viable layouts? JR – Yes there are. Some states with very heavy truck traffic choose to use a 4 bar pattern per wheel path but this is only in extreme conditions. Meandering transverse cracks can also be addressed with DBR as long as you center the bar on the crack, but this requires a longer slot at times to accommodate the length of bar thereby increasing the material and labor costs. 16. I have seen a note in the past that doesn't allow pavement grinding between June 10 and Sept 5 due to warm temperatures, and that grinding shall only be performed between the hours of midnight-10AM. Is this a national best practice? For example, on an urban arterial street. JR – No, not at all. The peak season for grinding is May through November and there are no warm-temperature limitations associated with grinding. Night grinding is very common due to traffic concerns but by no means necessary. 17. If we have doweled concrete pavement, is there a certain distance you have to be from the joint if we want to use DBR for mid-slab cracking to avoid slab replacements? JR – There are no hard and fast requirements pertaining to this but it is good practice to be several feet away from the (doweled) joint to prevent third stage cracking in the area. mailto:jroberts@igga.net 18. If your blade spacing is inappropriate for the aggregate type and you get a section with large fins, what is the remedy? Do you change the blade spacing and redo, or can you use a motor grader to skim the surface and pop them off? JR - If the number of fins is significant the contractor should stop and restack the head with thinner spacers. Randomly occurring fins here and there often break off under the first day or two being subjected to traffic. A grader can remove fins as well with little damage to the pavement as long as it meets your final smoothness specification. 19. Can diamond grinding effect the freeze thaw resistance of the concrete? Water/ice/snow seeps into the indentation from the diamond griding. Does this not effect the friction of the surface? JR - Typically not. The grooves created by grinding are no deeper that the grooves imparted to the concrete from transverse or longitudinal tinning. The MNDOT has reported that they have improved safety performance on their diamond saw cut surfaces as they retain deicing chemicals. See MNDOT video by pasting the following link in your web browser.. https://youtu.be/urGtJIuKNaQ 20. Is DBR more suitable for concrete pavement without dowels at the original construction joints? How would you retrofit the DBR between the originally installed dowels? JR – DBR is best applied to undoweled pavement slabs in good shape exhibiting faulting. If you have faulting on a slab(s) that already has mechanical load transfer (dowel bars), you need to do a thorough investigation to see why and how much dowel bar socketing is taking place. It is likely caused by a poor base, undersized dowels, corroded dowels or weak concrete. Some states have in the past placed DBRs in between existing bars with some success but in cases like this it is likely that a full depth repair in these locations is a better investment of one’s money. 21. Is the joint reformer left in place or removed after joint is filled? JR – The joint reformer is essentially removed by the joint sawing operation that takes place after the retrofit is installed. The sawing operation recreates/cleans the sealant reservoir in anticipation of the joint resealing operation (which is done after the diamond grinding operation). 22. Is there a point where too many dowel bar retrofits in a small area, which replace the original dowels, can negatively affect the life of the pavement? JR – Absolutely. Assuming that you have a significant amount of cracking, it may be more appropriate to utilize full depth repair. Numerous cracks in confined areas may indicate that you have a base or drainage issue that need be addressed prior to repair. Full depth repair would expose these areas and allow for the proper remedy to be applied. 23. Please comment on the diamond grooving operation. When would you recommend diamond grooving in addition to diamond grinding (i.e. NGCS)? JR – It is important to recognize that applying grooving on top of a diamond ground surface is different than the Next Generation Concrete Surface (NGCS). NGCS is a hybrid diamond saw-cut surface that does in fact utilize both grinding and grooving but is quite different than a grooved, diamond ground surface. NGCS is designed to have a very low noise signature with high friction characteristics. It is used in areas where tire/pavement noise is of high concern. Grooving applied on top of a diamond ground surface is done when you have a soft aggregate that is prone to polishing. The grooving is applied to extend the life of the saw-cut surface and reduce the potential for wet weather accidents well into the future. 24. JR mentioned that sealing of the joints should be done after diamond grinding and grooving. My understanding was that if the joints are properly sealed, grooving shouldn't pull the sealant out, and so sealing can be done before grinding and grooving, which prevents effluent from getting into the joint. What are your thoughts on this? JR – When constructing a DBR project, it is relatively safe to expect that there is a measure of joint faulting (stepping) or at least movement at the joints. This typically would tear the joint sealant away from the joint reservoir walls leaving an unsealed condition. DBRs perform far better when moisture is sealed out and away from the repair, hence the recommendation that sealing follow the grinding operation (that is used to remove the faulting). In short it is rare that properly sealed joints would be found in a typical DBR candidate. Sealing before or after grinding/grooving is another lengthy discussion that must consider a number of important factors on its own aside from the DBR process. Whenever possible sealing is best conducted after grinding and grooving. 25. Should (or do) agencies account for an increased thickness in PCCP at initial construction to account for the thickness reduction during diamond grinding? JR – Yes. Agencies that consider the whole life cycle of the pavement cradle to grave will add sacrificial thickness to their pavements and bridge decks to account for subsequent diamond grinding in the future. Other agencies simply rely on the ongoing strength development of the concrete throughout its life span to account for the removal of concrete thickness due to the grinding process. See RT Update attached. RT Update DG Affect on Structural Capacity 26. Slide 48 - do the fins that break off under traffic cause windshield damage? JR – No. The fins are typically wafer thin and contain no mass, so it is very unlikely to happen. 27. The essential part of DBR is concrete material in slots. Variation of this concrete materials, cement content, and aggregate thermal coefficient with the concrete pavement will increase the risk of cracking in the slot or in the boundary of the slot that will decrease the bonding and dowel efficiency. Please explain more about the mix design of concrete used in slots. JR - It is important to pay attention to the modulus of the two (new and existing) concrete materials to ensure a good bond and minimal cracking within the DBR section. Experience has shown that using aggregates from similar sources (controlling factor) and backfill materials that minimize shrinkage are always recommended. 28. Using a 4 ft grinder tends to leave a lip between adjacent passes, which can be a safety hazard for motorcyclists. Can you speak briefly about this, and how to avoid this problem? JR – Most grinding specifications require a straight edge measurement transversely to prevent this condition. This is entirely preventable. Informed inspection and enforcement should be applied to prevent this from happening. 29. What is the difference between diamond grinding and longitudinal tining? JR – Diamond grinding is a process that uses a grinding head consisting of closely spaced diamond tipped saw blades to remove a thin layer of hardened pavement surface to improve ride quality, reduce noise and improve safety (by providing an escape for water trapped beneath the tire and the pavement). Longitudinal tinning is a process whereby a wire comb is drawn across a green (freshly placed/uncured pavement) concrete pavement surface to impart drainage channels to improve safety (by providing an escape for water trapped beneath the tire and the pavement). Tinning will not improve smoothness or reduce tire pavement noise however. It should be noted that tinning is cheaper than diamond grinding. 30. What is the expected service life following the DBR and diamond grinding before the next major rehabilitation/reconstruction? JR – That depends on a number of factors including age and condition of the pavement prior to DBR, climate, traffic (trucks), base type, quality of construction and inspection etc. MANY DBR projects across the country have achieved 20 yrs (and counting) life with little maintenance. According to the Washington State DOT (WSDOT has installed over 700,000 DBRs since 1992), the condition of the pavement prior to the DBR is the most important factor. They state that applying the DBR process early in a pavement’s life is a significant factor in the repair longevity. JE- Oklahoma Turnpike Authority answer – We expect 15-20 years before the panels will need a major replacement, however, another grinding could be done if needed due to budgetary constraints. 31. What is the minimum thickness of the existing concrete slab to be a viable candidate for DBR? JR – A PCCP with 7 inches of thickness is viable although DBR has been constructed on concrete overlays as thin as 6.5 inches thick. See CALTRANS Report on Colfax Test Location (7 inch thick DBR) and IGGA Case Study on MN DBR (6.5 inch thick DBR). Caltrans-DBR_Evaluat ion-July2002.pdf CSJune2017_MN_do wel_bar_retrofit.pdf 32. What is the typical cost for diamond grinding per square yard? JR – It depends on many factors including aggregate hardness and size, amount of removal, project size, wage rates, traffic control, working hours etc. On large projects with reasonable conditions (as listed above) prices would likely range from $2.50 to $5.50 per sq yd but can vary widely based on site specific conditions. If you have specific projects in mind it is best to contact IGGA and ask for an estimate to be more exact. 33. What longitudinal angle you advise for grinding? JR – The diamond grinding texture is applied parallel to the centerline joint in most situations. Areas such as shoulders, auxiliary or ramp lanes may require a different orientation based on site conditions. 34. When diamond grinding, what is the best way to treat the adjacent areas that are not being diamond ground, such as asphalt shoulder. The diamond grinding will remove material/lower the profile and may result in uneven surface between the ground surface and the surface that is not ground. JR – In situations like this, it is advised to include a requirement for a feather pass of grinding over these areas (into the shoulder or gutter) in the project bid documents. The IGGA recommends the following language in its sample grinding specifications: “When conditions require a feather pass into the shoulder, auxiliary or ramp lanes, payment will be by the square yard based on a width of 2 feet times the length of the required feather pass. The minimum length of a feather pass will be 100 feet. Gutter sections requiring a feather pass will be paid by the square yard based on a width of 1 foot times the length of the required feather pass. The minimum length of a feather pass will be paid as 100 feet.” JE - Oklahoma Turnpike Authority answer – our plans require the contractor do daylight the grind across the shoulder. Most of the outside shoulder was ground between 2 and 4 feet from the edge of the concrete panel. DBR Webinar – Questions and Answers (1/12/21) | |
| Portland Cement Concrete PCC Overlays: Fabric and Fiber | 👤 Tom Cackler 👤 Dan King | Concrete Lunch & Learn | Winter 2020–2021 |
| 2021-01-11 | PCC Overlays Fabric and Fiber January 8, 2021 Tom Cackler, P.E. Dan King, P.E. Representing the CP Tech Center Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Background – International Practice • > 40 years of use by German Engineers • Geotextile fabrics have been used as a separation layer between: • full-depth concrete pavements and stiff cement treated bases • Concrete overlays over rubblized or crack & seated pavements (not common US practice) • The current specification in the US was based upon the German Specification 3 Use of Geotextile Materials for Separation in Concrete Overlay Applications Background - US Practice • 2006 International Technology Scanning Program (FHWA , AASHTO, & NCHRP) • Identified the technology as potential beneficial for concrete overlay applications • Recommended evaluation as an alternative to HMA 4 Use of Geotextile Materials for Separation in Concrete Overlay Applications Purpose of Separation Materials • Isolation from movement of the underlying pavement • Drainage • Bedding – a cushion of the overlay to reduce • Curling and warping stresses • Bearing stresses • Effects of dynamic traffic loads • Prevent keying 5 Use of Geotextile Materials for Separation in Concrete Overlay Applications Summary of current specification 6 Use of Geotextile Materials for Separation in Concrete Overlay Applications First US Project in 2008 • Missouri DOT – Route D • Clarkson Construction Co. • Originally built 1986 • 9,300 AADT • Severe D Cracking • 45,000 sq. yds. • 5” thick • 6’ joint spacing • 12 & 15 oz Fabrics (with heat treatment) • Thermal treated 7 Use of Geotextile Materials for Separation in Concrete Overlay Applications Second US Project - 2009 • Oklahoma – I 40 • Duit Construction Co. • Originally built 1969 • 9” JPCP over 4” asphalt base • 681,000 sq. yds. • 10 “ thick • 15’ joint spacing • 15 oz Fabric (imported from Germany) 8 Use of Geotextile Materials for Separation in Concrete Overlay Applications US Applications • Since 2008 > 10 m sy (2017) • Non woven 13 & 15 oz • JPCP overlay over • JPCP • CRCP Performance Assessment of Nonwoven Geotextile Materials Used as the Separation Layer for Unbonded Concrete Overlays of Existing Concrete Pavements In the US (Aug. 2018) - 9 Use of Geotextile Materials for Separation in Concrete Overlay Applications Summary of US Applications • Municipal Streets • County Roads • Primary Highway • Interstate Highways • Airports 10 Use of Geotextile Materials for Separation in Concrete Overlay Applications US Performance Overview • Geotextile separation has worked well for a wide range of overlay thickness and loading • Eliminates stripping of Asphalt separation layer • Appears to reduce panel migration • Adhesives work effectively for securing the fabric • Can provide significant cost and time savings • Provides adequate drainage with proper outlets • Match fabric thickness to the overlay thickness 11 Use of Geotextile Materials for Separation in Concrete Overlay Applications US Performance Overview Can provide significant cost and time savings • Cost (Iowa bid results 2015-2017) $2.07 - $2.45/ sq. yd. for geotextile fabric $4.86/ sq. yd. for 1” asphalt • Time Normally eliminates need for subcontract Easier execution for the paving contractor Does not control the paving progress 12 Use of Geotextile Materials for Separation in Concrete Overlay Applications • Panel Movement 13 Use of Geotextile Materials for Separation in Concrete Overlay Applications Stripping may occur in the asphalt interlayer of an unbonded concrete overlay pavement when the interlayer contains trapped water and under repeated heavy truck traffic, results in the water stripping the asphalt binder from the aggregate. Presenter Presentation Notes Stripping occurs in the asphalt interlayer of an unbonded concrete overlay pavement when the interlayer contains trapped water, due to poor drainage and under repeated heavy truck traffic, results in the water stripping the asphalt binder from the aggregate. Thus stripping results in the loss of bond between aggregates and asphalt binder that typically begins at the bottom of the HMA layer and results in the loss of structural support. Bottom-up stripping is difficult to recognize because it manifests itself on the pavement surface as other forms of distress including rutting, shoving/corrugations, raveling, or cracking. Asphalt overlays over existing open-graded surface course can result in stripping. Usually stripping take several years to develop the best preventive solutions are as follows: Provide positive drainage for the asphalt interlayer under heavy truck traffic loading consider using drainable asphalt mixtures similar to the gradation used by Michigan DOT. This asphalt mixture may be found in the Guide to Concrete Overlays third edition (Chapter 5, page 78, table 18). The interlayer should be delighted to the edge of the shoulder or subdrain system installed. Incorporate anti-strip additives such as lime in the asphalt. Lime has been found to be more effective than liquid anti-stripping additives. Sealant joints in concrete overlay and at the shoulder to help prevent water intrusion in the asphalt interlayer. Use of Geotextile Materials for Separation in Concrete Overlay Applications Iowa Applications • 20 projects (ICPA database) • 1,083,966 sq. yds. • 2013 to date • 4” – 7” overlay thickness • 16 county; 4 municipal 15 Use of Geotextile Materials for Separation in Concrete Overlay Applications • Ongoing Evaluations • Required geotextile thickness on thinner overlays? • Is there advantage in UBCOA applications? • Color advantage (White, black, gray) • Fatigue life/deflections 16 Use of Geotextile Materials for Separation in Concrete Overlay Applications Mn Road findings • 3” overlay with 6’ X 6’ panels • 8 oz and 16 oz fabrics • The thinner fabric resulted in • > strain • > IRI • > surface distresses • 4 decibels quieter • Recommended staying with current spec until further studies can examine other thicknesses 17 Use of Geotextile Materials for Separation in Concrete Overlay Applications Poweshiek V-18 • Built in 2008 with 2 test sections with geotextile • Deflection testing in 2018 • Resilient modulus >40% • Permanent deformation < asphalt sections 18 Use of Geotextile Materials for Separation in Concrete Overlay Applications Buchanan – D 16 • Built 2020 • 6” UBCOA • 2 fabrics ( 6 & 12 oz) • White and black color • Will re-test this summer 19 Use of Geotextile Materials for Separation in Concrete Overlay Applications • Construction procedures • Pre-overlay repairs • Placement • Anchoring options • Fabric thickness guidance 20 Use of Geotextile Materials for Separation in Concrete Overlay Applications • Resources- https://cptechcenter.org/concrete-overlays/ • Guide Specs • Typical Plans • Design Procedures • Performance History • Use of fibers • Training materials • Handouts • Videos 21 Fiber-Reinforced Concrete Overlays 22 Outline • Background • Design and Construction • Fiber-Reinforced Concrete Overlays in Iowa • Recent Projects • New Applications and Ideas 23 Background 24 What is Fiber-Reinforced Concrete? • Concrete reinforced with discrete, distributed fibers • Macro-fibers and micro-fibers • Different materials: steel, glass, synthetic, natural Images: Sika 25 What is Fiber-Reinforced Concrete? • Concrete reinforced with discrete, distributed fibers • Macro-fibers and micro-fibers • Different materials: steel, glass, synthetic, natural Images: Sika 26 What is Fiber-Reinforced Concrete? • Reinforcing with synthetic macro-fibers: • Increases the fracture toughness and post-crack load capacity of concrete • Does NOT increase compressive, tensile, or flexural strength of concrete • Some decrease in workability • Reduction in bleeding, plastic shrinkage cracking • Reduces crack widths • Increases resistance to cracking 27 Benefits of Fibers in Concrete Pavements • How the properties of FRC translate to pavement performance: • Improves long-term fatigue performance • Keeps joints and cracks tight • Enhances aggregate interlock • Prevents panel movement/sliding • Design implications: • Improves design life/reduces thickness • Improves load transfer • Allows for longer joint spacings? Image: CP Tech Center 28 Concrete Overlays • Concrete overlays are a particularly good application for fibers • Improves fatigue life of a thin slab • Enhances aggregate interlock when the pavement is often too thin to place dowel bars for load transfer 29 Concrete Overlays • Fiber-reinforced concrete has been used to construct bonded and unbonded concrete overlays in all types of applications: city streets, county & state highways, and interstate highways 30 Design and Construction 31 Designing FRC Overlays • How do I choose a dosage rate for fibers? • A dosage of 3 to 5 lbs/cy of synthetic macro-fibers has been common for concrete overlays, including in Iowa • About 0.2 to 0.3% by volume • How was this rate determined? Image: Forta 32 Designing FRC Overlays • ASTM C1609 testing to determine residual strength (f150) • The common dosage rate (3 to 5 lbs/cy) for FRC overlays corresponds to f150 = 100 to 200 psi for most macro-synthetic fibers Images: CP Tech Center 33 Designing FRC Overlays • How does using fibers affect the design? • Current practice: add the residual strength to the design flexural strength to produce an effective flexural strength • Tool available on CP Tech Center website to help determine a design value for residual strength: • https://cptechcenter.org/publications/ • Click the “Spreadsheets” sub-heading v1.1, Bordelon and Roesler (2019) 34 https://cptechcenter.org/publications/ Designing FRC Overlays • You may use this effective flexural strength value in any design tool to obtain an overlay thickness design accounting for fibers • Different fiber products – different f150 values at different dosage rates • In some concrete overlay design tools like BCOA-ME, all you need to do is plug in a fiber dosage rate, and the software adjusts the design accordingly according to its own assumptions 35 Constructing FRC Overlays • Construction Considerations • Mixing • Ensure fibers are well-dispersed • May require an increase in mix time • Workability • May need to adjust admixtures • At especially high fiber dosages (> 7 lbs/cy or > 0.5%), may need to increase paste content • Finishing 36 Constructing FRC Overlays • Paving 37 Constructing FRC Overlays • Paving 38 Constructing FRC Overlays • Paving 39 FRC Overlays in Iowa 40 FRC Overlays in Iowa • Micro-fibers on experimental concrete overlays 1970s to 1990s • Greene County • IA 21, Iowa County (1994) • First test sections with synthetic macro-fibers on state highways in the early 2000s • IA 13, Delaware County (2002): • 3 lbs/cy dosage rate 41 FRC Overlays in Iowa • Later in 2000s and into 2010s, adoption of fibers began on thin concrete overlays on city streets • Le Mars (2010-2018): 42 FRC Overlays in Iowa • Most recently, more FRC overlays on county highways • Mitchell County (2017): • 4 lbs/cy fibers 43 New Applications and Ideas • FRC overlays with synthetic macro-fibers have performed well in Iowa and across the US dating back to the 2000s • Over time, fiber products continue to improve in performance and mixing characteristics • What new ideas are out there for concrete overlay applications? 44 New Applications and Ideas • Optimizing Joint Spacing • Thin concrete overlays (4 to 6 inches) commonly have short joint spacing • Cracks don’t always form beneath joints right away on these thinner overlays, which could be a problem • Additional cost & maintenance for design that may not work as intended • Potential for dominant joint behavior 45 New Applications and Ideas • Can we better optimize joint spacing design for low-volume roads? • Are shorter slabs always necessary? • Will cracks consistently form beneath joints as designed? • Can we measure differences/impact on curling behavior, ride quality? • Do fibers help with the ability to potentially extend joint spacing? Short slab designs Figure: Gross et al. (2017) 46 New Applications and Ideas • FRC test sections built in Mitchell & Buchanan Counties (2017-18) • 4 and 6 inch overlay sections, 4 lbs/cy fibers • Joint spacing varying from 6 ft x 6 ft up to 20 ft transverse • Joint activation monitored from construction to one year 47 New Applications and Ideas • Results so far: • Most of the joints are cracking as intended (approaching 100% activated joints through 1.5 years) • The section with the fewest joints activated was 4 inch overlay with fibers and 6 ft x 6 ft slabs (70% activated) • Future testing and performance monitoring will help fully understand impacts of joint spacing and fiber- reinforcement Figure: Gross et al. (2019) 48 New Applications and Ideas • If not all joints crack right away, especially when using fibers, maybe early loading of the slab can help activate the joints? • US 63, Minnesota: 49 New Applications and Ideas • What if we increased fiber dosage rate and let the pavement crack on its own? • Worth County test section (2019) • 6 inch FRC overlay, typical 4 lbs/cy and 12 ft x 12 ft joint spacing • 7.5 lbs/cy fibers for test section • Increased cementitious content from 570 to 640 lbs • No transverse sawed joints in the test section – pavement allowed to crack on its own 50 New Applications and Ideas • Paved in October 2019 • Initially: 7 transverse cracks in 636 ft section 51 New Applications and Ideas • Cracks developed progressively throughout the year • Earlier/larger cracks filled • By December 2020: 24 total transverse cracks • Average crack spacing = 26.5 ft • Average crack width = 0.036 inches (~1/32 inch) • Widest cracks = 0.08 inches (~1/12 inch) 52 PCC Overlays �Fabric and Fiber�January 8, 2021 Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Use of Geotextile Materials for Separation in Concrete Overlay Applications Fiber-Reinforced Concrete Overlays Outline Background What is Fiber-Reinforced Concrete? What is Fiber-Reinforced Concrete? What is Fiber-Reinforced Concrete? Benefits of Fibers in Concrete Pavements Concrete Overlays Concrete Overlays Design and Construction Designing FRC Overlays Designing FRC Overlays Designing FRC Overlays Designing FRC Overlays Constructing FRC Overlays Constructing FRC Overlays Constructing FRC Overlays Constructing FRC Overlays FRC Overlays in Iowa FRC Overlays in Iowa FRC Overlays in Iowa FRC Overlays in Iowa New Applications and Ideas New Applications and Ideas New Applications and Ideas New Applications and Ideas New Applications and Ideas New Applications and Ideas New Applications and Ideas New Applications and Ideas New Applications and Ideas Slide Number 53 | |
| Concrete Pavement Thickness Design and Slab Geometry | 👤 Tyler Speakmon 👤 Tommy Nantung | Concrete Pavement Technology Tuesday Webinar | 2021 |
| 2021-01-07 | 1 Concrete Pavement Thickness Design & Slab Geometry Tyler Speakmon, PhD Infrastructure Solutions Engineer CEMEX USA – Commercial Cement Agenda Review of Pavement Design History & Pavement Types Distresses Related to Pavement/Slab Geometry Compare AASHTO 93 vs Pavement ME Designs Incorporating Slab Geometry into Design Tools Using Slab Geometry to Control Cracking Mechanisms Thickness Joint Spacing Widened Lanes Additional Design Considerations and Jointing In The Beginning… Early Concrete Pavement Details The first concrete pavements/slabs were: ≈ 6” thick… no real structural design 6’ to 8’ slabs No crack control joints or dowels/steel 2 Design Challenge | Solution Vehicles Speeds Increased Loads Increased People Noticed Joint Roughness & Wanted to Maximize Production to Minimize Cost | Minimize Construction Joints Less of this and more of this! CONCRETE PAVING SOLUTIONS USING CONVENTIONAL CONCRETE Jointed Plain Concrete Pavement (JPCP) Continuously Reinforced Concrete Pavement (CRCP) Jointed Reinforced Concrete Pavement (JRCP) Shorter slabs w/ dowels & aggregate interlock to transfer loads Continuously reinforced to control crack width Longer (than JPCP) jointed w/ dowels to transfer loads 30 – 100 ft. 10 – 16 ft. or 2 – 6 ft. Longitudinal joint (incl location & spacing) Transverse joint (incl location & spacing) Subgrade Subbase or base Surface texture Surface smoothness Thickness design Dowel bars Concrete mix design Tiebars JOINTED PLAIN CONCRETE PAVEMENTS (JPCP) – Key Design Items Design requires understanding how design features impact cost and performance (and getting the right balance for the application) Design also Requires an Understanding of How a Concrete Pavement Fails… Structural Distress – the ability to carry traffic Functional Distress – the ability to serve the user comfortably Joint Faulting (dominant) Insufficient Texture/friction (address through maintenance) Joint Faulting (dominant) Cracking (dominant) Rough ride (IRI) (mainly due to cracking and faulting) 3 Rigid Pavement Design Tools/Methods AASHTOWare Pavement ME (previously known as DARWin-ME and MEPDG) AASHTO 93 (software as ACPA WinPAS) 325 & 330 AASHTO 93 / WinPAS ESAL = # of 18 kip (8,165 kg) equivalent single axles needed to cause same “response” Because pavement responses are different for concrete and asphalt, ESALs are different for the same exact traffic loading… ESAL ≠ traffic ESALs depends on thickness, among other things Flexible ESALs generally about 1/3 less than rigid ESALs for highway-type traffic; NEVER COMPARE RIGID & FLEXIBLE ESALs Equivalent Single Axle Loads (ESALs) TRAFFIC IS THE MAIN SOURCE OF DAMAGE FOR PAVEMENTS The Magnitude of Damage Depends on Vehicle Number, Type, and Load Equivalent Single Axle Loads (ESALs) ESALs • Assumes traffic is only 18,000 lbs single axles • Conversion of trucks to ESALs is empirical • Based on field test conducted 50 years ago • Traffic conditions significantly changed between now and then Load Spectrum • Consider traffic composed of axles w/ different weights • Required inputs: • Number of trucks • Axle load spectrum • Function of roadway type Single Tandem Tridem 4 46.8 7 )1( 10*624.1 1 5.15.4 06.0)1(*35.7*)( D PSI Log DLogsZESALLog oR 25.0 75.0 75.0' )/( 42.18 **63.215 )132.1(** *)*32.022.4( kE DJ DCS Logp c dc t Standard Normal Deviate Overall Standard Deviation Thickness Change in Serviceability Terminal Serviceability Drainage Coefficient Load Transfer Modulus of Rupture Modulus of Elasticity Modulus of Subgrade Reaction 1986-93 JPCP AASHTO 93 Equation Traffic WinPAS Makes it Easy! AASHTO 93 Slab Geometry involved => Thickness Concrete Pavement Design Methodologies AASHTO 93 1962-1998 10 inputs “Performance” Field Data StreetPave 2005-2017 12 inputs Crack & Fault FEA + Field Data OptiPave 2009 - 2018 ≈ 50 inputs Crack, Fault, IRI FEA + Field Data Pavement ME 2009-2018 ≈ 1,000 inputs Crack, Fault, IRI FEA + Field Data Increasing Complexity = More Accurate Models & More Optimization Options TH E 40 Y EA R D IV ID E Current Design ToolsOutdated PavementDesigner 2018 - Present 12 inputs Crack & Fault FEA + Field Data Industry Developed Methods PavementDesigner.org 5 PavementDesigner.org Background A free tool designed to simplify concrete pavement design for: Parking lots Roadways (JPCP, RCC, CRCP, Overlays Unbonded & Bonded) Industrial / Intermodal yards (Forklifts & Specialty Equipment) Uses More Accurate Traffic Inputs PD.org Slab Geometry => Thickness & Joint Spacing MEPDG / DARWin-ME / AASHTOWare Pavement ME Pavement ME Design Not “perfect” & not intended to be a “final” product Complex and relatively costly Primarily for high volume roadways =+ Mechanistic Calculation of Responses Empirical Tie to Ground Pavement Performance Prediction Sounds Easy Enough, Right? 6 Concrete Pavement Design Options MEPDG / DARWin-ME / AASHTOWare Pavement ME Pavement ME’s Concrete Pavement Designs New Pavement Jointed Plain Concrete Pavement (JPCP) Continuously Reinforced Concrete Pavement (CRCP) Overlay Bonded PCC over JPCP or CRCP Unbonded JPCP or CRCP over JPCP or CRCP JPCP over AC CRCP over AC SJPCP over AC Rehabilitation Pavement ME Inputs… EXACT Traffic Inputs… 7 Pavement ME Outputs… Pavement ME Performance Outputs Jointed Plain Concrete Pavement (JPCP) JPCP Design Process General Info and Performance Criteria Traffic Details Climate Characterizing Pavement Structure JPCP Design Properties JPCP – Characterizing Pavement Structure 8 JPCP – Pavement Structure – PCC Materials Let’s Break it Down JPCP – Design Properties JPCP – Design Properties Let’s Break it Down JPCP – Design Properties SSA Doweled Joints Diameter Spacing 0.85 (Default and semi-constant) Typically used if thickness > 8 in Often depends on thickness 1 inch for 8 inches or less thickness 1.25 inches for 8 – 10 inches thickness 1.5 inches for >10 inches 12 inches is most common 9 JPCP – Design Properties Erodibility Base Friction Joint Spacing Depends on soil conditions Good defaults Typical range = 12 – 20 ft JPCP – Design Properties Curl/Warp Temp. Sealant Type Tied Shoulder Widened Slab -10oF (Good default) Preformed or Other (none, liquid, silicone) Project dependent Project dependent Pavement ME Slab Geometry Inputs include Thickness, Joint Spacing, Lane Width Summary of Unique JPCP Critical Inputs Performance Criteria IRI, Cracking, Faulting Thickness Joint Spacing Lane Width Shoulder Type Dowel Design PCC Strength PCC Modulus Coef. of Thermal Exp. Curing Method Base Erodibility Mix Design (Cement type, w/cm, etc.) BOLD => Inputs Related to Slab Geometry SHORT JOINT SPACING IMPROVES JPCP PERFORMANCE • Curling & warping is due to the differential drying and thermal shrinkage at the slab surface • Shorter slabs have less length, which means reduced curling Cantilever = 1/4 L Length 12 to 15 ft., cantilever = 3 to 3.75 ft Length 30 ft., cantilever = 7.5 ft Cantilever = 1/4 L Reduces Shrinkage Force Reduces Environmental Stress • ~1/4 of slab length is cantilever • Reducing unsupported length reduces the bending stress • Reducing length reduces uplift and improves smoothness Improves Load Transfer • Shorter slabs have smaller joint/crack opening • Agg. Interlock stronger for tighter cracks • High load transfer results in less stress in concrete ∆L ∆L/2 Shrinkage Force Lifting Force F/2 F/2 10 SHORT JOINT SPACING REDUCES SLAB CRACKING 0 10 20 30 40 50 60 70 80 90 100 12 13 14 15 16 17 18 19 20 Joint spacing, ft P e rc e n t sl a b s c ra c k e d 8-in slab 9-in slab 10-in slab 11-in slab 19 million trucks (TTC 2 [30 million ESALs]) Wet-freeze climate 8- to 11-in JPCP; 6-in aggregate base Joint Spacing vs. Slabs Cracked Graph Developed by Tommy E. Nantung INDOT Office of Research and Development Maximum Joint spacing = 18 to 24 times thickness (15 ft max) Engineering Solutions – Widened Slab Example (Rao, 2018) (Rao, 2018) Engineering Solutions – Widened Slab Example Widening the slab reduces longitudinal edge midpanel stresses but this could increase stresses in other locations not considered in Pavement ME With 14 ft wide slab there is a much higher risk of longitudinal cracking due to increased stresses at interior transverse joint edge locations (Rao, 2018) Engineering Solutions – Widened Slab Example 11 Highway Design Problem 7,860 trucks (~20M ESALs) 90% Reliability 5% Slabs Cracked 6 lane facility R-Value = 20 MOR = 630 psi EPCC = 3,500,000 psi • Edge Support • HMA Subbase = 1” • Cement Stb Subgrade = 6” • K = 160 psi/in • Design: • AASHTO 93 = 11” • PavementDesigner = 8.5” • Pavement ME = 9” Additional Design Considerations Related to Slab Geometry Dowels Dowel Spacing Dowel Bar Diameter Edge Support Tie Shoulders Jointing Layouts …CRCP Design Properties Top 10 ME Design Most Sensitive 1. Concrete Flexural Strength at 28-Days 2. Concrete Thickness 3. Surface Shortwave Absorptivity (SSA) 4. Joint Spacing 5. Concrete Modulus of Elasticity at 28-Days 6. Design Lane Width with a 14 ft (4.3 m) Widened Slab 7. Edge Support via Widened Slab 8. Concrete Thermal Conductivity 9. Concrete Coefficient of Thermal Expansion (CTE) 10. Concrete Unit Weight http://onlinepubs.trb.org/onlinepubs /nchrp/docs/NCHRP01-47_FR.pdf Engineering Solutions - Faulting Improve Mechanical LT Increase Dowel Size Decrease Dowel Spacing Decrease Joint Spacing Increase Width of Lanes Reduce Underlying Layer Erosion Increase Erodibility Index Decrease Joint Spacing Reduce Thickness Only if Cracking is Passing 12 Sensitivity of JPCP Faulting to Dowel Diameter 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0 50 100 150 200 250 300 350 Age, months F au lt in g fo r 10 in ch s la b, in s 1" dowel 1.25" dowel 1.375" dowel 1.5" dowel Sensitivity of JPCP IRI Sensitivity to Dowels 0 50 100 150 200 250 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Pavement age, years IR I, in /m i 1.25-in dowel 1.375-in dowel Non-doweled 19 million trucks (TTC2 [30 million ESALs]) 9.8-in slab; 15-ft joint spacing 6-in aggregate base 28-day MRpcc = 690 psi; Epcc = 4.4 Mpsi Sounds Easy Enough, Right? Continuously Reinforced Concrete Pavement (CRCP) Resources: Rasmussen et al. (2011) Roesler et al. (2016)Roesler & Hiller (2013) Check out crcpavement.org for more! 13 CRCP Design Properties Related to Slab Geometry Lane Width Crack Spacing (Dependent on Steel Design & Base Friction) Steel Design % Steel Bar Diameter Bar Depth Base Friction Coefficient Shoulder Type Pavement ME Allows Agencies To Develop And Use Local Calibration Coefficients You can save your local calibration coefficients as default or restore the national as default at one click Local Calibration Examples Indiana DOT: Changed JPCP IRI J3 from 1.4929 to 1.05 because it was too sensitive to it Ohio DOT: Changed JPCP IRI calibrations Many states at this point are working on or have completed local calibrations. Calibration Coefficient Default (national) Ohio PCC IRI J1 0.8203 0.82 PCC IRI J2 0.4417 3.7 PCC IRI J3 1.4929 1.711 PCC IRI J4 25.24 5.703 PCC IRI JPCP Standard Deviation 5.4 5.4 Local Calibration Result In ½-In Or Less Difference In Required Thickness Vs. National Calibration However, using Pavement ME result in ~2-3 in thinner JPCPs when compared to the AASHTO 93 guide. Low Volume Application High Volume Application Pavement ME_LC Pavement ME_NC AASHTO 1993 4 6 8 10 12 AZ IA KS MO NY OK SC VA WY Pa ve m en t T hi ck ne ss , i n A Z D E IA IN KS LA M O N C N Y O H O K PA SC U T VA W A W Y 300 250 200 150 100 P a v e m e n t T h ick n e ss, m m A A S H T O 1 9 9 3 (Mu, 2017) 14 Simpler ME Option: Design Tables Conclusions: • Slab Geometry is KEY to Optimizing Pavement Designs • Thickness is not the ONLY Slab Geometry that Improves Performance • Shorter Joint Spacings & Widened Lanes Improve Pavement Performance • Improvements in Design Tools, such as Pavement ME, have allowed Designers to Utilize all aspects of Slab Geometry to Yield more Economical and Better Performing Concrete Pavements 125 Yrs of Success and Performance It’s all about the thickness… right? Acknowledgements & References Ferrebee, Eric 2020. AASHTOWare Pavement ME Design Workshop. Presented to Arkansas DOT. 2-27-2020. Mu, Feng 2017. Establish Pavement ME Design Inputs for New Jointed Plain Concrete Pavements, Presentation to TAC Pavement ME User Group Meeting, 4-21-2017. Rao, Shreenath 2018. Pavement ME Design – 3M Edition – Myths, Misuses, & Misconceptions, Presentation to 2018 CO/WY ACPA Meeting, 3-22-2018. Donahue, John & Jason Bloomberg 2018. AASHTO Pavement ME Design Web Application JPCP Module, Presentation to MO/KS ACPA’s 38th Annual PCCP Conference, 2-20-2018. 15 Resources NCHRP 1-37 MEPDG Home: http://onlinepubs.trb.org/onlinepubs/archive/mepdg/guide.htm Recorded Webinars: https://www.fhwa.dot.gov/pavement/dgit/aashtoware.pdf North American Usergroup Summary Page: http://www.pooledfund.org/Details/Study/549 ME Design Help: http://www.me- design.com/MEDesign/data/HTML%20Help/US/index.html?design_inputs_1.htm Application Library: http://apps.acpa.org/ Resources Some States with Pavement ME User Guides Michigan: https://www.michigan.gov/documents/mdot/MDOT_Mechanistic_Empirical_Pavement_Design_ User_Guide_483676_7.pdf Colorado: https://www.codot.gov/business/designsupport/matgeo/manuals/pdm/2017- m-e-pavement-design-manual/chapter-1.pdf Indiana: http://www.in.gov/indot/design_manual/files/Ch304_2013.pdf Arizona: https://apps.azdot.gov/ADOTLibrary/publications/project_reports/PDF/AZ606.pdf Virginia: http://www.virginiadot.org/VDOT/Business/asset_upload_file108_3638.pdf Utah: https://www.udot.utah.gov/main/uconowner.gf?n=20339215312776663 Q&A / Discussion Thank you ! Concrete Pavement Thickness and Slab Geometry Indiana Experience Tommy E. Nantung Division of Research and Development Indiana Department of Transportation West Lafayette, Indiana Research Begins in 2000 from Indiana SR-49 Research Begins in 2000 Survey from Indiana Concerns Related to Slab Dimensions Concerns Related to Slab Dimensions One axle in each end Vertical load = 4 x 17.8 KN Pressure = 765 kPa Slab Analysis due to Load Slab-Subbase Contact Area Stress Analysis: Loading vs Temperature For SR 0.55 : log10 N = 11.737 12.077 SR For 0.45 < SR < 0.55 : N = ( 4.2577 / ( SR 0.4325 ) )3.268 For SR 0.45 : N = unlimited Temperature Loading Field Project for Verifications - 2005 Moved from thickness design to performance design Maximize the contribution of pavement foundation and pavement underdrain Designers have to do trials by varying the slab dimensions to achieve efficient designs with the highest performance Indiana MEPDG Implementation JPCP Cement Treated Soil Soil Subgrade INDOT 2005 MEPDG Sensitivity Analysis Parameter Roughness Faulting Percent Slabs Cracked Permanent Curl/Warp Effective Temperature Difference VS (Very Sensitive) VS VS Joint Spacing VS VS VS Dowel Bar Diameter MS (Moderately Sensitive) MS NS Pavement Thickness S (Sensitive) MS VS MS MS S Coefficient of Thermal Expansion VS VS VS Thermal Conductivity S MS VS Decision for Implementation of Changes in Slab Dimensions Reduce the joint spacing to less than 18 feet Use tied pavement shoulder or widened slabs with HMA shoulder Use widened slab with tied pavement concrete shoulder Use of integrated tied pavement inside shoulder with the passing lane Use of conservative dowel bar sizes Prepare for the adoption of the MEPDG (in 2008) Prepare traffic and materials inputs for the MEPDG Slab Dimensions Options Shorter Joint Spacing 16 and 15 feet Thickness is reduced by 1 to 2 inches Shorter Joint Spacing + widened slab Thickness is reduced by 2 to 2.5 inches Slab Dimensions Options Shorter Joint Spacing + widened + tied shoulder Thickness is reduced by 2 to 3 inches Shorter Joint Spacing + widened + integrated shoulder Thickness is reduced by 2 to 2.5 inches The First MEPDG Interstate Pavement Design I-465 Designed with AASHTO 1998 Supplemental for 18 foot joint spacing and the thickness was 16 inches Designed with MEPDG version 1.0 for 16 foot joint spacing and 14 inches, tied shoulder, not widened slab Final I-465 Design Summer 2010 0 5 10 15 20 25 30 35 40 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 P e rc en t s la b s c ra ck ed , % Pavement age, years Predicted Cracking Percent slabs cracked 0 30 60 90 120 150 180 210 240 270 300 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 IR I, in /m ile Pavement age, years Predicted IRI IRI Designed with MEPDG version 1.0 for 16 foot joint spacing and 14 inches, tied shoulder, not widened slab Reduced the joint spacing to maximize performance from a thinner pavement Changed order in February 2010 Constructed in Summer 2010 I-465 Performance after 10 years I-465 Performance after 10 years Zero crack at all lanes, none in the heavy truck lane (3 &4) Some cracks in bridge approaches on embankments Joint faulting less than 1 millimeter Truck lanes are Lane 3 and 4 The 2nd MEPDG Interstate Pavement Design I-69 Designed with AASHTO 1998 Supplemental for 18 foot joint spacing and the thickness was 13 inches Designed with MEPDG version 1.0 for 16 foot joint spacing and thickness of 10 inches, HMA shoulder, and widened slab Final I-69 Design Summer 2012 Designed with MEPDG version 1.0 for 16 foot joint spacing and 10 inches, HMA shoulder, widened slab Reduced the joint spacing and implement widened slab to maximize performance from a thinner pavement Constructed in Summer 2012 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 F au lt in g , i n Pavement age, years Predicted Faulting Faulting 0 30 60 90 120 150 180 210 240 270 300 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 IR I, in /m il e Pavement age, years Predicted IRI IRI I-69 Performance after 7 years I-69 Issues due to Pavement Soil Settlement Issues of soil (shale) settlement in embankment fill sections in some areas leading to premature failures I-69 Issues due to Pavement Soil Settlement Challenges and Limitations of Slab Dimensions Base, subbase, and subgrade foundation issue Soil type, construction, and soil settlement issue in the fill sections Slab Dimension Limits Joint Spacing and 16 Lane Width 1:1 (L:W) ratio with 14 inches thickness tied to moment slab Joint Spacing and 16 Lane Width Slab Dimension Limits Core from US-31 1:1 (L:W) ratio with 14 inches thickness tied to moment slab Joint Spacing and 16 Lane Width on I-70 Slab dimension Limits and Possible Solution Conclusions Designers have the authority to explore the layers compositions and thicknesses to maximize the contribution of the pavement foundation to approach a better pavement predicted performance. The next step is to alter the slab dimensions and thickness and other design features to reduce the thickness of the pavement to still meet the pavement predicted performance. Designers have to be very verse and aware of each design features and slab dimensions to achieve efficient designs and have successful projects, there are trade offs. So far, the most successful and best performer projects since 2010 MEPDG are either shorter joint spacing, widened slab, or both. Design Webinar – Questions and Answers The questions submitted during the webinar follow with answers that our speakers have provided. 1. Can PavementDesigner.org be used online and not have to download it, which requires IT permission? FL PavementDesigner.org is exclusively an online tool and there is nothing to download. Currently Pavement ME is only available as a downloaded software, but an online version is being developed with a release date sometime in 2022. 2. What would be the optimal joint spacing and slab width?, Quebec It depends on the trials in the MEPDG. The first trial has to be optimization of the pavement foundation and begin with 18 feet of joint spacing (to reduce the cost of joint cutting and sealing) and a standard 12 feet of width. If the performance prediction shows that your trial design cannot pass because of cracking, you need to reduce the joint spacing to 17 feet and do the trial again, and so on. If you already reach 15 foot joint spacing and still cracking cannot pass, you begin to use widened slab. If still cannot pass the cracking criteria, you have to begin increase the thickness little by little. But most of the time, the IRI is a very sensitive factor that determine the design in non-interstate highways, not the cracking criteria. 3. OptiPave is a really interesting concept. Can we do this same thing to significantly lower slab stresses by cutting slab lengths and widths in half? TX Yes. OptiPave allows engineers to design shorter optimized slab dimensions, which can reduce stresses and result in thinner concrete pavements. This is a similar concept to what is used in the design of bonded concrete overlays in the BCOA-ME design tool from the University of Pittsburgh and the SJPCP module in Pavement ME. However, it should be noted that this design process is patented and it has not been widely used in the US for highway, street and roadway design (although it has been evaluated technically at the University of Illinois and has been used fairly extensively for highways in Chile and other places in South America). 4. Has the reduction in predicted cracking (and faulting) with a widened slab been verified, or driven by reduction in edge stresses by moving the wheel loads off the free edge? IL Indiana is doing right now. We have a research study to do another local calibration to include the I-465 (10 years old) and I-69 (7 years old) to see the differences. In the previous research study in 2000 the calculation using finite element (by Purdue University) indicated reduction of the edge stress because of moving the wheel wander away from the edge. See ongoing Indiana SPR-4447 Research Study and SPR-2643. Link: https://docs.lib.purdue.edu/jtrp/47/ https://www.engineering.pitt.edu/Vandenbossche/BCOA-ME/ https://apps.ict.illinois.edu/projects/getfile.asp?id=3012 https://docs.lib.purdue.edu/jtrp/47/ 5. "Why are there only two options for ME regarding sealing (performed and others)? IL This is because when the MEPDG models were created, most State DOTs LTPP sections used pre-formed (in only some small portion of pavement) and silicon sealant or hot pour asphalt sealant. Some State DOTs use silicon sealant for transverse joint (because it is more flexible for larger slab opening movement) and hot-pour asphalt sealant for the longitudinal joints (because of smaller slab opening movement). This is to calculate spalling that influences roughness in the joints. Now, there are many state DOTs don’t seal their pavement joints. See https://trid.trb.org/view/1263162. 6. If we use CTB and bonded it with PCC layer, would curling stress and cracking reduce especially top down cracking? IL Indiana uses only one project so far with CTB, in US-24 in 2010 as an experimental statement. The surface of the CTB had a very thick curing compound to reduce significantly the bonding with the JPCP. The CTB is open graded 1 inch size aggregate and it was a weak concrete, so reflection cracking was not a concern. Based on the FWD testing the curling stress is higher compared to the ATB (asphalt treated base). This is exactly what Prof. Michael Darter predicted in his report on Zero-Maintenance Pavement. See https://trid.trb.org/view/51136 7. Do you recommend bonding between CTB and PCC?" IL So far Indiana has constructed only one section for experimental CTB bonded to the JPCP. Just recently during the Summer 2020 we tried unbonded using plastic sheet. Time will tell about the performance. 8. Is the theory that the wider slab that helps the pavement life is that it helps it to have the panels more square? IA No, not at all. The purpose is to move the wheel wander away from the edge of the pavement edge. That is why the width of the slab is 14 feet but the delineator line (the white line) is still 12 feet. Since most of the Class 9 trucks have wheel spacing in an axle of about 8 feet, if the trucks travel right in the middle in between the lines, the tandem axle wheels will be about 3 feet from the pavement edge. This will reduce the stresses from the pavement edge that will initiate the fatigue cracks. See https://ops.fhwa.dot.gov/Freight/publications/size_regs_final_rpt/index.htm 9. Can you share the rule of thumb about joint spacing vs thickness again? PA The joint spacing-thickness ratio in the 2000 Indiana pavement survey is joint spacing (in feet) divided by thickness (in inches). State DOTs that implemented ratios between 1 to 1.25 in their interstate pavement do not experience issue with mid-slab cracking. See https://docs.lib.purdue.edu/jtrp/47/ https://trid.trb.org/view/1263162 https://trid.trb.org/view/51136 https://ops.fhwa.dot.gov/Freight/publications/size_regs_final_rpt/index.htm https://docs.lib.purdue.edu/jtrp/47/ 10. So the prediction of cracking using MEPDG for the 14 in slab was 0% (for 50% reliability)? If that was the case why not reducing the thickness further to be closer to the cracking threshold by the end of the analysis period? PA I actually reduced the pavement thickness in I-465 to 13.5 inches but the Chief Engineer overruled my design due to the unknown risk. This is because the MEPDG software was still in the “trial” software by the NCHRP not as mature as the one today in PavementME. In addition, the I-465 is the first interstate pavement in the nation that was designed with the MEPDG. 11. Is there a max number of tie bars to use in a 14 ft widened slab to prevent longitudinal cracking? OH Indiana used the tie bar design from the A Mechanistic-Empirical Tie Bar Design Approach for Concrete Pavements by ACPA, the spacing is 3 feet. Indiana assumed the tie bar is not for load transfer. See https://trid.trb.org/view/905652 12. Can you get longitudinal cracking with a 14 ft widened slab and 7 tie bars into an 8 ft wide shoulder? OH With #7 bar, it is not likely, especially with 2 feet tie bars spacing (I believe Ohio is still 2 feet). However, it all depends on the pavement foundation. So far the issue of longitudinal cracking is related to pavement foundation. Research performed in Louisiana, Iowa and Wisconsin suggest that widened slabs, shoulder type, joint spacing and orientation, slab thickness, base type, and traffic volume were among design features that influenced the initiation and severity of longitudinal cracks Sources: D. Ziao and Zhong Wu. Longitudinal Cracking of Jointed Concrete Pavements in Louisiana: Field Investigation and Numerical Solution, International Journal of Pavement Research and Technology, Volume 11, Issue 5, pg. 417-426, 2018. H. Ceylan, Y. Zhang, S. Yang, O. Kaya, K. Gopalakrishnan, and P. Taylor, Prevention of Longitudinal Cracking in Iowa Widened Concrete Pavement, Iowa Highway Research Board Project TR-700, Ames, IA, 2018. S. Owusu-Ababio and R. Schmitt, Longitudinal Cracking in Widened Portland Cement Concrete Pavements, Department of Civil Engineering, University of Wisconsin-Platteville, Platteville, WI, 2013. 13. Do you research on bound breaker effects on slab contribution with base layer to reduce curling stress? Also, do you think we can go toward geometry design optimization with stabilized base layer? If yes how we can control reflective cracking? Italy https://trid.trb.org/view/905652 Our research for CTB (Cement Treated Base) with JPCP was done in 2010. It is actually not fully bonded because we used heavy during compound on the top of the CTB before placing the JPCP. Compared to the ATB (Asphalt Treated Base), the ATB gives significantly less curling stress. Geometry of the slabs can be altered after you maximize the contribution of the foundation to the pavement. In the US “stabilized base layer” is a very weak concrete with open graded gradation. With heavy curing compound and weak CTB, reflective cracking will not occur. It is not LCB (Lean Concrete Base) that is implemented in Germany and many countries in Europe when they bond the LCB with the JPCP. To control the reflective cracking they cut transverse joints in the LCB and line up the joint in the JPCP at the same locations 14. How does integral curb and gutter impact the slab width geometry? IA In Indiana pavement design guide, the slab width geometry in the design will not change. If the curb and gutter section has a width of more than 4 feet we treated that as “tied pavement shoulder” 15. Was it a surprise how wider pavements performed with joint faulting? NY In MEPDG faulting is influenced by the size of the dowel bar, temperature curling and moisture warping, passing #200 of the subgrade material, erodibility of the base and subbase, and the number of wet days. Since the top 14 inches of subgrade in Indiana is treated with cement 4%, the passing #200 of the subgrade is reduced significantly. The base and subbase are also very erosion resistant (dolomitic limestone). So the excess faulting due to the pavement curling of warping from the widened slab can be countered by the size of the dowel bar (which is very cheap, the difference between 1.25” dowel and 1.5” dowel is only 50 cents). Therefore, the principle of the MEPDG design is to maximize the pavement foundation and make adjustments to the pavement design features later by trials in design. 16. Did the presenter say that a tied PCC shoulder can additionally reduce the mainline pavement thickness similar to the widened slab? Would the thickness of the tied shoulder need to be the same thickness as the mainline PCC? SD Yes, tied shoulders will reduce the thickness of the mainline slab. In 2010 when we first implemented the MEPDG, the FHWA had a rule that for travelled/usable pavement shoulder the thickness had to be designed with 10% of the truck traffic in the mainline with a minimum thickness of 9 inches. I designed only one new pavement section using this method, in SR-25 in Indiana (see enclosed Figure 1 for a different thickness of HMA shoulder, but in SR-25 I changed that with 9 inch concrete shoulder and tied the shoulder to the mainline pavement). As a result, the pavement shoulder thickness is not always the same as the thickness of the mainline pavement. The most important thing is to assume the tie bars to tie the pavement and the pavement shoulder with #6 bar with 2 foot tie bar spacing, and therefore the deadload of the pavement shoulder will counter the curling stress. However, we don’t practice that anymore due to the constructability. Contractors have to construct separately the pavement shoulder and the mainline. Source: See enclosed Figure 1 for the old different shoulder thickness and Figure 2 from the current Indiana design manual. Figure 1 Figure 2 Design Webinar – Questions and Answers | |
| Performance-Engineered Mixtures PEM and Reduced-Cement Paving Mixes in Iowa | 👤 Todd Hanson 👤 Dan King | Concrete Lunch & Learn | Winter 2020–2021 | 2020-12-14 | PEM and Reduced Cement Paving Mixes in Iowa Todd Hanson, P.E., Iowa DOT Dan King, P.E., Iowa Concrete Paving Association Introduction • Overview of PEM Program • Iowa Paving Mixes and PEM Interest • FHWA Trailer Visit • PEM Shadow Testing 2019 • I-29 Harrison County Project PEM • Future Outlook for PEM Performance Engineered Mixtures • Pooled fund study led by CP Tech Center uniting FHWA, champion state DOTs, and the concrete paving industry https://cptechcenter.org/performance-engineered-mixtures-pem/ https://cptechcenter.org/performance-engineered-mixtures-pem/ Performance Engineered Mixtures • Implementing current best practices and new methods for: – Designing and specifying concrete pavement mixtures for maximum long-term durability – Measuring and relating early age concrete properties to performance Performance Engineered Mixtures • Prepare the mixture for the application – Use what you need (and no more) from the materials you have – Control cementitious content • Require the things that matter – What do we need to design for to maximize durability in our environment? – What tests/measurements do we perform to make sure we meet our goals? What matters to us? • Cold weather resistance (cold locations) – SAM Air Meter, LTDSC- Salt Resistance • Transport properties/permeability (everywhere) – Resistivity/Formation Factor • Aggregate stability (everywhere) – ASR/D-Cracking • Workability (everywhere) – Box Test/V-Kelly • Strength (everywhere) – Flexural or Compressive • Shrinkage (dry locations) – Ring Test How do we proportion to achieve design goals? Workability Transport Strength Cold weather Shrinkage Aggregate stability Aggregate System Type, gradation - - - - Paste quality Air, w/cm, SCM type and dose Paste quantity Vp/Vv - - - - Controlled mixtures • Control the cementitious content – Excess has a: • Negative effect on permeability, shrinkage, cost • Small negative effect on strength – “Optimum” depends on: • Aggregate type • Gradation • Aggregate shape 8 Super Air Meter (SAM) • Test at 14.5, 30 & 45 psi – Release and repeat • Air content & SAM number • SAM number correlates to spacing factor => F/T Test • Mix Design SAM # <0.20 • Field SAM # <0.30 & Air>6% Workability • Slump Test – Uniformity Test tells nothing about response to vibration • Box Test and V-Kelly – Response to Vibration • Factors in Workability – Aggregate Gradation – Paste Content – Admixtures Workability - Box Test • Fill box to 9.5 inches • Insert vibrator 12,500 vpms – 3 seconds to bottom – 3 seconds out • Edges of box are removed and inspected • PEM Limits <30% Voids or Rating of 2 or less Transport Properties - Resistivity • Cast Two Cylinders • Place in bucket with (Ca, Na, K) hydroxide solution • Test Resistivity at 3, 7, 28, 56 and 91 days Calcium Oxychloride Potential • Salts can cause chemical attack – Reaction between Ca(OH)2 & CaCL 2 or MgCl 2 expands ~30% & forms above 32F • Low temperature differential scanning calorimetry (LT-DSC) – 10 gms hydrated paste ground, mix w 10 mg 20% CaCl2 solution, low temperature cycling • Limit the CaOXY formation to < 0.15 (g/100g) reduces oxychloride formation • Potential reduced by use of SCMs Iowa Paving Specifications • In many ways, the goals and ideas of the PEM program are familiar to Iowa • In recent decades, we’ve seen the introduction of QMC and C-SUD paving mixes Development of QMC Specification • 1997 First (QMC) project – Incentive Compressive Strength • 1998 -1999 12 projects – Incentive Third Point flexural • No Correlation of Strength to Durability • Minimal Mix Improvement Development of QMC Specification • In 2000, Incentive based on Shilstone Gradation Chart • Variations of incentive boxes • 2016 Incentive removed – Provide proportions in Zone II • Minimal workability issues past 20 years – Aggregate Shape Effect QMC – Aggregate Shape • US 75 Woodbury Co. 2000 • Quartzite CA & IA – 45.5% CA/ 19.5% IA/ 35% FA • Very Coarse w Angular Aggregates – Finishing difficulties – edge tear – slow production rates QMC 20 Years Lessons Learned • Partnership with contractors expedited changes • Placement impacts durability • Excessive handling with soft aggregates affect strength • Well graded aggregates improve placement • Aggregate shape and texture affect placement • Slag and fly ash reduce permeability • Optimized gradation allows for reduction in cementitious content and w/cm C-SUD Paving Mixes • While QMC was implemented by the DOT, local agencies in Iowa also needed to adapt their mixes to new trends – Greater de-icing demands, impacting long-term durability C-SUD Paving Mixes • The C-SUD specification allows local agencies to optimize the gradation according to the QMC specification • Plus additional options: – Greater allowable fly ash & SCM substitution rates (35-40%) • Additional protection against CaOXY formation from de-icing salts – Further lowering of maximum w/cm (0.42) • This lower w/cm was adopted for QMC a few years ago, too How does QMC mix compare with PEM? 2018 PEM Pooled Fund Research Project • Shadow projects • Investigate ruggedness of test methods • Develop specification limits • Collect data for modelling • Contractor QC Testing • FHWA Mobile Concrete Trailer Iowa PEM Shadow Project • Cedar Valley Corp volunteered • US 20 Woodbury Co. 2018 • Comprehensive QC Plan • Control Charts • Air PWL – SAM Test – Box Test – Resistivity/Formation Factor – Calcium Oxychloride Potential – Trial batch mix design reduced cement Combined Aggregate Gradation 20 25 30 35 40 45 0 10 20 30 40 50 60 70 80 90 100 W o rk a b il it y (p e rc e n t) Coarseness Factor (percent) Average Project Workability Factor VS Coarseness Factor IV II I III V Boundary Line Combined Aggregate Gradation 0 5 10 15 20 25 #200 #100 #50 #30 #16 #8 #4 3/8" 1/2" 3/4" 1" 1 1/2" P e rc e n t R e ta in e d Sieve Size Tarantula Curve Combined Aggregate Gradation, % Retained Very Low Low Moderate High Calcium Oxychloride Potential • Limiting CaOXY formation to less than 0.15 (g/100g) • 20% Class C fly ash replacement met the limit • Higher percent slag/ fly ash replacement will further reduce potential US 20 CaOXY formation - different fly ash replacement rates PEM Mix Design w Lower Cement Content Dr. Taylor estimated cement content based on dry rodded unit weight of combined aggregate. • Investigate lower cement mix on shoulders – 4 ft. by 6 in. thick • Validate mix using PEM tests 550 lbs 515 lbs A-2-C20 Mix Abs. Vol. lbs/CY CEMENT: 0.083 440 FLY ASH: 0.025 110 WATER: w/c=0.474 0.155 261 FINE AGGREGATE: 0.305 1357 COARSE AGGREGATE: 0.372 1680 INTERMEDIATE AGG.: 0 0 AIR: 0.06 0 Paste Content, % 26.3 PEM Mix Design • Some concerns lowering cement content of standard A mix for shoulder – Used QMC proportions • Performed trial batch – Box Test • Placement went very well • Average w/c 0.42 PEM Mix Design QMC vs PEM - What We Learned Iowa DOT Current Practices QMC • Strength – avg 640 PSI Flexural • Volume of Paste = 24.3% • w/c Ratio = 0.42 max. • Air Content 6 to 10% • SAM Results all below 0.30 • Ca Oxychloride Limit =0.15 g/100g • Formation Factor ~1000 • 20% C ash • Aggregates – Iowa DOT Methods • Workability Good • Combined Aggregate Grading QMC vs PEM - What We Learned • FHWA Mobile Concrete Lab closeout session • Current QMC practices pretty good • Possibly add resistivity testing • Investigate Reduced Cement Mixes 2019 PEM Data 2019 PROJECT AVERAGES Location SAM # BOX # W/C Resistivity Polk I35 0.23 1.2 0.39 11.89 Harrison I29 0.22 1.1 0.40 15.67 Black Hawk US 20 0.18 1.4 0.40 7.15* Plymouth US 75 0.20 1.3 0.40 12.64 *Aggregates with high absorption affect results 2019 I-29 Harrison County • With success of reduced cement mix in 2018 • Trial reduced cement mix on I-29 outside shoulder – 10ft wide, 11 inch thick – Mainline 24’ & Inside 6’ Shoulder paved integral • Trial Batch – Box Test & SAM Test 2019 I-29 Harrison County Shoulders A-6-C20 Mix Abs. Vol. lbs/CY CEMENT: 0.092 463 FLY ASH: 0.027 116 WATER: w/c=0.474 0.163 274 FINE AGGREGATE: 0.395 1744 COARSE AGGREGATE: 0.263 1188 INTERMEDIATE AGG.: 0 0 AIR: 0.06 0 Paste Content, % 28.2 484 lbs579 lbs 2019 I-29 Harrison County Shoulders A-6-C20 • 579 lbs/cy • Avg w/c ratio = 0.392 PEM • 484 lbs/cy • Avg w/c ratio = 0.413 • Mainline 2020 decided to increase cement content due to w/c ratio – Later, found out a water reducer was not included in the mix. I-29 Harrison QMC vs PEM QMC Mix Design 2019 Material Weight (lbs/yd3) Ash Grove IP Cement 426 Nebraska City Fly Ash (20%) 107 Weeping Water CA (45%) 1427 N. Valley Cl. V. Aggregate (55%) 1708 Water (basic w/c=0.40) 0.42 max 213 PEM Mix Design 2020 Material Weight (lbs/yd3) Ash Grove IP Cement 399 Nebraska City Fly Ash (20%) 100 Ft. Calhoun CA (45%) 1441 N. Valley Cl. V. Aggregate (55%) 1752 Water (basic w/c 0.40, 0.42 max. 200 533 lbs 499 lbs I-29 Harrison QMC vs PEM • Trail batch 2020 mix for mainline • Mixed at plant and hauled to grade • Paving began after trial batch • 2019 – wet conditions • 2020 – hot, dry I-29 Harrison QMC vs PEM I-29 Harrison QMC vs PEM I-29 Harrison QMC vs PEM I-29 Harrison QMC vs PEM I-29 Harrison QMC vs PEM I-29 Harrison QMC vs PEM >20.7 Very Low I-29 Harrison QMC – PEM Summary • Average w/c ratio – QMC 2019 = 0.396 – PEM 2020 = 0.390. • Smoothness-Zero Band – QMC 2019 24.87 in/mi • 58.4% Max possible Incentive – PEM 2020 19.26 in/mi • 72.7% Max possible Incentive Summary • Iowa QMC Mixes comparable with PEM Mix • PEM testing helped validate reduced cement content QMC mixes (QMPEM) – 0.099 Abs Vol Cement – (1st Iteration) • 524 lbs/cy Type I/II • 517 lbs/cy Type IS(20) • 499 lbs/cy Type IP(25) – Trial Mix Design - SAM Air Test and Box Test – QC Testing - SAM Meter 1/day, Box Test – 1/day, Resistivity if available • Influence of Aggregate Shape on cement content Influence of Aggregate Shape US 20 Project I-29 Project ??? PEM - Future • Continue gather data on SAM testing, workability, resistivity, etc. • Get a SAM Meter and practice using – Purchase – FHWA or ICPA equipment loan • Box Test – Build box – Vibrator requirements – https://www.minnich- mfg.com/products/vibrators/flex-shaft/csv • Investigate lower cement mix with other aggregate combinations • Eventually, modify QMC DS https://www.minnich-mfg.com/products/vibrators/flex-shaft/csv Contractor’s Perspective Thank You ! https://intrans.iastate.edu/app/uploads/2019/03/Mixture-proportioning-2019-09.xlsx https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fintrans.iastate.edu%2Fapp%2Fuploads%2F2019%2F03%2FMixture-proportioning-2019-09.xlsx&data=04%7C01%7CTodd.Hanson%40iowadot.us%7C6015a079c44249b0911808d89c4aef9b%7Ca1e65fcc32fa4fdd86920cc2eb06676e%7C1%7C0%7C637431193443132830%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=D4tBVpG2fVC%2Blr69Fo8ZdI%2BzhuWotbgvpKIwJ72CHo0%3D&reserved=0 | ||
| Life-Cycle Cost Analysis (LCCA) in Pavement Design | 👤 Leif Wathne 👤 Jeremy Gregory | Concrete Pavement Technology Tuesday Webinar | 2020 |
| 2020-11-18 | Life Cycle Cost Analysis: Basics & What Matters? CP Tech Center/ACPA Webinar November 17, 2020 Leif G. Wathne, P.E. American Concrete Pavement Association Jeremy Gregory, PhD Massachusetts Institute of Technology Life Cycle Cost Analysis: Basics & What Matters? 1) Introductory content based on information in ACPA’s LCCA Engineering Bulletin (EB011) and wikipave.org 2) What have we learned & key takeaways from work at What is Life-Cycle Cost Analysis? Life-cycle cost analysis (LCCA): An analysis technique used to evaluate the overall long-term economic efficiency between competing functionally equivalent pavements (i.e. equal benefits to the user…). Based on well-founded economic principles. Identifies the strategy that will yield the best value by providing the expected performance at the lowest cost over the analysis period. Is not an engineering tool for determining how long a pavement design or rehabilitation alternative will last or how well it will perform. Why Bother with an LCCA? Pavement types perform differently over time, and equivalent designs are not always achievable during initial construction. LCCA compares the total discounted cost of each design over a specific analysis period to minimize the financial burden of the roadway on taxpayers. This is nothing new! AASHO in 1960, supported the concept of LCCA FHWA embraced LCCA in its 1981 policy statement on Pavement Type Selection. Congress in 1995 required LCCA for projects on the NHS. Rescinded in 1998 (section 1305 of TEA-21), as States pointed to a lack of guidance regarding LCCA In 1998, FHWA issued Interim Technical Bulletin, and has since developed guidance, demos and issued RealCost. 2020 House-passed Moving Forward Act, included Sense of Congress that States should use LCCA…. Basic Steps in a Single Project LCCA Life-Cycle Cost Analysis NOTE: Predicated on equivalent alternatives Step 1 – Select the Analysis Period Life-Cycle Cost Analysis LCCA Analysis Period The analysis period is the timeframe over which the alternative strategies/treatments are compared. Must encompass the initial performance period and at least one major follow-up preservation/ rehabilitation activity for each strategy. FHWA recommends an analysis period of at least 35 years for all pavement projects. ACPA recommends an analysis period of 45-50+ years because common practice in many states is to design the concrete pavement alternate for 30+ years. Step 2 – Select a Discount Rate Life-Cycle Cost Analysis LCCA Discount Rate The real discount rate (also known as the real interest rate) is used in pavement LCCAs. Accounts for fluctuations in both investment interest rates and the rate of inflation (can be materials specific… MIT forecasting) Today’s costs can be used as proxies for future costs. d = 1 + 𝑖𝑖𝑛𝑡 1 + 𝑖𝑖𝑛𝑓 − 1 d = the real discount rate, % iint = the interest rate, % iinf = the inflation rate, % Determining the Real Discount Rate If local interest and inflation rates are not readily available to develop a local real discount rate, FHWA recommends OMB Circular A-94 Appendix C Published annually – December 2019 Current OMB Rate is 0.4% FHWA GUIDANCE: USE REAL DISCOUNT RATES PUBLISHED ANNUALLY in OMB CIRCULAR A-94 5 .4 3 .7 4 .8 7 .9 5 .6 6 .4 7 .4 6 .7 4 .4 5 .6 6 .1 4 .6 4 .2 3 .8 4 .5 2 .8 4 .9 3 3 .6 3 .8 2 .9 4 .2 3 .2 3 .9 3 .2 3 .5 3 .1 3 3 2 .8 2 .7 2 .7 2 .3 2 1 .1 1 .9 1 .4 1 .5 0 .7 0 .6 0 4 19 79 19 80 19 81 19 82 19 83 19 84 19 85 19 86 19 87 19 88 19 89 19 90 19 91 19 92 19 93 19 94 19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 In 1998, FHWA Interim Bulletin suggested 4% based on a 5-yr average of OMB rates… OMB 30-Yr Real Interest Rates Per Circular A94 Appendix C Step 3 – Estimate Initial Agency Costs (A) Life-Cycle Cost Analysis Initial Agency Costs Only those initial agency costs that are different among the various alternatives need to be considered for reasonably similar alternates. Pavement costs include items such as subgrade preparation, bases, and surface material; associated labor and equipment, etc. When historical bid prices are used as estimates, consider the impact of material price escalators, payment practices (sy v. tons), bidding practices (shifting), job size, etc.. Initial Agency Costs Important to get as correct as possible! Influences results more than anything else in analysis Do not use average bid values blindly Easiest or toughest to get??? Step 4 – Estimate User Costs (B) Life-Cycle Cost Analysis User Costs Costs that are incurred by users of the roadway over the analysis period, mainly.... Work zone costs: Incurred during lane closures and other periods of construction, preservation/rehabilitation, and maintenance work. Vehicle operating costs: Incurred during the normal use of the roadway (roughness and stiffness) Step 5 – Estimate Future Agency Costs (C) Life-Cycle Cost Analysis Future Agency Costs All cost components must be considered because the present value of costs associated with engineering, administrative, and traffic control are impacted by the time value of money (timing, discount rate). Include multiple rehab scenarios! Must include rehabilitation costs and timing. Preservation and Rehab. Costs Large future agency costs associated with improving the condition of the pavement or extending its service life. Preservation and rehabilitation activities and their timing should be based on the distresses that are predicted to develop in the pavement. Best to develop pavement performance predictions based on local performance history data; otherwise, AASHTOWare Pavement ME can be used. Step 6 – Estimate Residual or Salvage Value Life-Cycle Cost Analysis Residual or Salvage Value Defined in one of three ways: The net value that the pavement would have in the marketplace if it is recycled at the end of its life, The value of the remaining service life (RSL) at the end of the analysis, OR The value of the existing pavement as a support layer for an overlay at the end of the analysis period. Residual or salvage value must be defined the same way for all alternatives. Always in final year, so Δ$ is what is important. Step 7 – Compare Alternatives Life-Cycle Cost Analysis Pavement Management Plan from City of Leawood, Kansas Compare Alternatives Alternatives considered must be compared using a common measure of economic worth. Investment alternatives such as pavement strategies are most commonly compared on the basis of: Present worth (also called net present value [NPV]) Annual worth (also called equivalent uniform annual cost [EUAC]) NPV and EUAC provide the same ranking Analysis Methods Deterministic approach – a single defined value is assumed and used for each activity. Probabilistic approach – variability of each input is accounted for and used to generate a probability distribution for the calculated life-cycle cost. Analysis Tools Most modern spreadsheet software include standard functions for calculating the present worth and annual worth. Proprietary software to compute LCCAs include: FHWA’s RealCost (deterministic and probabilistic) ACPA’s StreetPave & WinPAS (both deterministic) CAC’s CANPave (deterministic) Asphalt Pavement Alliance’s (APA’s) LCCA Original and LCCA Express (both deterministic) Compare Results Because different components of the LCCA indicate different things about the alternates, the components typically are viewed separately and together to aid in interpretation/ evaluation. LCCA is a decision support tool! When two alternatives have very similar net present values over the analysis period, it is advisable to choose the less risky alternative (i.e., the one with the higher proportion of the net present value attributable to initial costs). For LCCAs within 10-15%, use ADAB (leverage competition) So… WHAT REALLY MATTERS? Lessons learned and key takeaways from work at MIT’s Concrete Sustainability Hub… 1/7/2021 1 Important Issues in Pavement LCCA Jeremy Gregory Research Scientist and Executive Director, CSHub CP Tech Center Concrete Pavement Technology Webinar November 17, 2020 Slide 2 Core elements of CSHub approach Integrate LCCA & LCA into design process Incorporate uncertainty into all analyses Statistical data analysis for model inputs Engineering and science modeling of important phenomenon Analyses of performance, cost, and environmental impacts for various contexts Slide 3 Integrate LCA & LCCA into design process 10.0” JPCP w/ 1.25” Dia Dowels Subgrade 6.0” Agg Subbse Design Proposal & Context Layers Traffic Climate Analyze Using ME Design Principles Develop Lifecycle Bill of Activities Evaluate LCCA / LCA NN YYAdequatePerformance 8.0” JPCP w/ 1.25” Dia Dowels Subgrade 6.0” Agg Subbse Final Design Performance-to-activity model • Material quantities • Construction activities • Maintenance timing • Logistics LCCA • Magnitude & timing of cash LCA • Inputs Emissions Pavement-ME CSHub created linkage between design tools and evaluation Slide 4 Incorporate uncertainty into all analyses Statistically Characterize Uncertainty Propagate uncertainty to understand risk Present Future LCA/LCCA Model Is the difference significant? Relative risk Characterize drivers of uncertainty Pavement Design Output 1/7/2021 2 Slide 5 Characterize uncertainty for agency and user parameters Construction Operation C as h F lo w Agency: • Unit-price of inputs • Quantity of inputs Agency: • Quantity of inputs • Future construction prices • Maintenance timing User: • Traffic delays & fuel loss Slide 6 Statistical data analysis for model inputs DegradationInitial costs Future costs Slide 7 Deflection & Roughness Excess Fuel Consumption (EFC) Economic & Environmental Impacts Pavement Deflection Pavement Roughness Pavement-vehicle interaction (PVI) Engineering and science modeling of important phenomenon Slide 8 • Pavement designs • Maintenance schedules • Design life • Analysis period 4 Locations FL: Wet no freeze MO: Wet freeze CO: Dry freeze AZ: Dry no freeze 3 Traffic Levels • Rural local street/highway • Rural state highway • Urban interstate Several framing conditions Pavement design and maintenance schedules developed by Applied Research Associates (ARA), Inc Analyses of performance, cost, and environmental impacts for various contexts 1/7/2021 3 Slide 9 Functional equivalence is critical for pavement comparisons Design life equivalency: Time until first major rehabilitation Combination of design and maintenance/rehabilitation schedule These are not functionally equivalent 11 22 To create equivalence: 1. Increase asphalt design life, or 2. Decrease concrete design life Slide 10 Key insights from research Life cycle perspective is important Context is important Excess fuel consumption drives user costs Uncertainty is important for inputs and outputs Slide 11 Initial construction costs 47% Future maintenance and rehabilitation costs 53% Total life-cycle costs for a state highway in Florida Flexible pavement design developed by Applied Research Associates (ARA), Inc,: AADTT 1k/day; 4 lanes; Wet-no-freeze-FL; FDOT-based rehabilitation schedule; Analysis period = 50 years. Life cycle perspective is important Future costs can be significant Slide 12 Life cycle perspective alters relative competitiveness 0 0.5 1 1.5 2 2.5 In it ia l C o st A B 0 0.5 1 1.5 2 2.5 3 3.5 R e a l P ri c e L C C A B (millions $) (millions $) Initial cost only: 17% difference Life Cycle Cost: ~0% difference 1/7/2021 4 Slide 13 Initial costs 98% Rehab costs 2% Interstate, rigid design Initial costs 79% Rehab costs 21% Interstate, flexible design Initial costs 47% Rehab costs 53% State highway, flexible design Initial costs 89% Rehab costs 11% Local highway, rigid design Costs vary with location, traffic level, & pavement design Context is important Slide 14 Minnesota concrete pavement with asphalt shoulders Design developed by MNDOT Initial 62% M & R 16% User Cost 22% Traffic Delay 4% Excess Fuel Consumption 96% Excess fuel consumption drives user costs Slide 15 0% 10% 20% 30% 20 60 100 140 180 220 260 300 340 380 420 460 500 540 580 Ev en t O cc u rr en ce a s a Pe rc en ta ge Unit Price of Concrete ($/CY) Distribution of Unit Price of Concrete for Pavement Projects Source: Caltrans 12 months of project bid data from the CalTrans database What is driving variation in initial costs? Uncertainty is important for inputs Slide 16 Capture drivers of initial cost and variation through statistical models 0 2 4 6 8 0 4 8 12 Lo g U n it- P ri ce ( $/ C Y ) Log Quantity (Cubic Yards) Concrete material prices highly dependent on quantity used on job Initial cost is usually major driver of variation in probabilistic comparative pavement LCCAs 1/7/2021 5 Slide 17 There is uncertainty in future price projections But probabilistic projections are plausible Concrete (grey) Asphalt (black) 50 100 150 200 2010 2020 2030 2040 2050 R e al P ri c e In d ex ( Y ea r 20 13 = 1 00 ) Year Slide 18 CSHub forecasts have been shown to be more effective than current assumptions 0% 20% 40% 60% 0 5 10 15 20 A ve ra g e E rr o r o f F o re ca st Years into the future CSHub Forecasting Model Current Practice In c re a s in g P e rfo rm a n c e Testing the effectiveness of the model for the state of Colorado Real price projections outperform conventional assumptions of no real price change Slide 19 0% 25% 50% 75% 100% 2.00 2.50 3.00 3.50 4.00 F re q u e n cy Net Present Value of LCC (million $) Probabilistic LCCA provides insight on relative risks B A 8% diff @ mean 10% 30% 15% diff @ 90th perc. Uncertainty is important for outputs Slide 20 Robust comparisons: confidence in a result despite uncertainty 0% 4% 8% 12% 16% 20% -0.2 0 0.2 0.4 0.6 0.8 1 NPV Design B – NPV Design A NPV Design A Design A costs lessDesign B costs less How frequently does design A cost less than design B? Design A costs less than design B in 90% of simulations statistically significant result 1/7/2021 6 Slide 21 Probabilistic analysis illuminates key parameters driving variation in final cost 0% 5% 10% 15% 20% Factor 1 Factor 2 Factor 3 … C on tr ib u ti on t o Va ri an ce Initial cost is usually major driver of variation in probabilistic comparative pavement LCCAs Slide 22 Key insights from research Life cycle perspective is important Context is important Excess fuel consumption drives user costs Uncertainty is important for inputs and outputs More information available at: http://cshub.mit.edu/ cshub@mit.edu We have worked with many agencies to review their LCCA practices. We’d be glad to work with you. LCCA Webinar – Questions and Answers (11/17/2020) The questions submitted during the webinar follow with answers that our speakers have provided. Resources: · EB011P: https://wikipave.org/index.php?title=EB011_-_Life-Cycle_Cost_Analysis · OMB Circular: https://www.whitehouse.gov/wp-content/uploads/2020/12/M-21-09.pdf Can you please say about the user cost comparison to the initial cost? I mean what is the percentage of user cost we expect for a 20-year design of asphalt and concrete pavement with respect to the initial construction costs? California This is entirely dependent on traffic, as user costs are mostly related to traffic (work zone costs and vehicle operating costs)… In very high traffic situations, user costs can dwarf initial costs. For lightly traveled roads, user costs can be minimal. How does the rate of excess fuel consumption change as more and more vehicles move toward electric? Does the battery consumption increase as the deflections and IRI of the roadway increases? Kansas Great question. The excess energy consumption stays the same, but the energy now comes from a battery (that in turns gets its energy from coal, wind, gas or whatever source the grid in that area is powered by) rather than from gasoline or diesel. The excess energy concept remains valid as vehicle fleets transitions to electric, but the overall CO2 footprint may be different as the energy used is from a different source. In short, yes, battery consumption goes up as deflections and roughness increases. How much is the difference between initial costs and future rehab & maintenance costs related to the design, materials or contractor quality control during construction? Is there a breakdown on the Florida example? Kansas We do not account for contractor quality in determining the need for future maintenance and rehabilitation costs, but it is an interesting question. One would need to have a clearly defined relationship between future pavement deterioration rates and construction quality. The maintenance and rehabilitation schedules we used were determined by the consultant we hired to create the designs and schedules (ARA), who based them on DOT practices. What functional unit would you propose to compare the following two road options in an LCA? Florida · Highway with 4,000 heavy vehicles a day and a useful life of 20 years. · A conventional road with 2000 heavy vehicles per day and a useful life of 40 years. Note that the carriageway widths are different. I assume the question is about LCCA and not LCA, although the functional equivalence question applies to both. An LCCA is used to compare two options that are functionally equivalent (i.e. equal benefits to the user). You should not attempt to use LCCA to decide between alternatives that provide totally different benefits. In your example, an LCCA would be inappropriate as the alternatives are not functionally equivalent. It’s much like comparing apples and oranges. Instead, one should compare design alternatives for the same requirements. This is typically done using the same traffic requirements and the same design life (time until a major rehabilitation), even though the pavement designs and maintenance and rehabilitation schedules among the two alternatives will be different. In respect of the LCA of a road pavement there is an ongoing debate as to whether to consider vehicle fuel impacts as road impacts or not. Please comment. Florida Again if the question pertains to LCCA (and not LCA), it is our perspective that if user costs are to be included in the LCCA (and that is not always the case), excess fuel consumption (related to roughness and stiffness) is appropriate to incorporate in this user cost. Generally, the AADT at the end of the design period will be higher than at the beginning. This means that the road must be sized for the amount of traffic expected on the road say 30 years from now. I would like you to reflect on this point. Do you have to size a pavement for your AADT at the end of its useful life, for your starter AADT or for an intermediate one? How does this affect the LCA for a road pavement? Florida This is really a pavement design question. You should design a pavement for the total expected loadings it will be experiencing during its design life. www.PavementDesigner.org does this in an intuitive and easy-to-use way. Again, an LCCA is an analysis technique used to evaluate the overall long-term economic efficiency between competing functionally equivalent pavements (i.e. equal benefits to the user). It is not a pavement design tool on its own – it is used in conjunction with pavement design. What is the limitation of Real Cost software? Iowa RealCost is free and robust tool for performing a Life-Cycle Cost Analysis. However, one limitation would be the program may be a bit too complicated for agencies that do not use it regularly. The introduction of user costs provides advanced users the capability to better predict and understand the impacts of construction activities, but does require additional information that may not be readily available. It is not as simple to get to the basic agency costs (including initial and maintenance / rehabilitation costs) because of this added complexity. Another basic limitation is the lack of default/example information in the tool. If RealCost had two modules, one basic and one advanced, the tool would be much more user friendly… What software do you suggest for LCCA and LCA? Iowa AND What are the free software programs for LCCA? Quebec There are several good options including FHWA’s RealCost. APA’s LCCA Express is also useful. Both FHWA’s RealCost and APA’s LCCA Express are free. If EUAC is used, as opposed to NPV, unequal lives is not a concern, correct? Wyoming Correct, as long as both alternatives compared in the LCCA are functionally equivalent (i.e. equal benefits to the user), AND the analysis period encompasses the initial performance period and at least one major follow-up preservation/ rehabilitation activity for both alternatives considered. Could you please elaborate about what is considered the LESS RISK ALTERNATIVE and the main criteria to consider for its determination? California In our case, risk is defined as the likelihood of exceeding a cost target. A lower-risk alternative will have lower costs but also lower uncertainty. The uncertainty is derived from many factors, but the largest determinant is the uncertainty in initial cost. Considering ACPA's recommendation for 40-45-year analysis period, asphalt pavements are often designed for 20 years, so how is this situation handled in LCCA? Minnesota [bookmark: _GoBack]Great question. Since LCCA is an analysis technique used to evaluate the overall long-term economic efficiency between competing functionally equivalent pavements (i.e. equal benefits to the user…), it is important to extend the analysis to a long enough period to capture the performance of both alternatives. The analysis period must encompass the initial performance period and at least one major follow-up preservation/ rehabilitation activity for each alternative considered. As concrete pavement is often designed for an initial performance period of 30 years, the analysis period is often 40 or 50 years to capture at least one follow-up rehab activity. Jeremy, could you please recommend some literature that discuss your topic? Minnesota You can find MIT Concrete Sustainability Hub resources on our web page dedicated to the topic: http://cshub.mit.edu/pavements/lcca. ACPA’s Engineering Bulletin EB011 also has a lot of good information. It is accessible on line at no cost. Many other sources are referenced in that document. www.wikipave.org/index.php?title=EB011_-_Life-Cycle_Cost_Analysis. Overall, great presentations! I wish practical examples had been presented to drive the key points home. Minnesota Thank you. Due to time constraints, we were not able to go through detailed case studies. However, we have several examples included in EB011 and on the CSHub LCCA web site (links above). Vehicle operation cost (VOC) is a function of pavement stiffness. Given that asphalt pavements are less stiff than PCC pavements, can we say asphalt pavements induce higher VOC, all factors being constant? Minnesota Exactly! And, we now have models that can tell you how much higher VOCs are, based on pavement characteristics. MIT CSH has a wealth of information about this phenomenon specifically! See: www.cshub.mit.edu/pavements/pvi. | |
| The Future of Fly Ash: Dystopia or Hysteria? | 👤 Larry Sutter | Iowa Better Concrete Conference | 2020 | 2020-12-02 | 12/3/2020 1 The Future of Fly Ash: Dystopia or Hysteria? Larry Sutter Ph.D., P.E., F.ASTM, F.ACI Materials Science & Engineering Michigan Technological University Background • We expect one key property from concrete: Longevity • Service demands have increased • Use of aggressive deicing chemicals • Increased expectations for reduced environmental impact and lower initial and lifecycle costs • SCMs assist meeting these goals Definitions • cementitious material, supplementary, (SCM) - an inorganic material that contributes to the properties of a cementitious mixture through hydraulic or pozzolanic activity, or both • DISCUSSION—Some examples of supplementary cementitious materials are fly ash, silica fume, slag cement, rice husk ash, and natural pozzolans. In practice, these materials are used in combination with portland cement. (ASTM C125) • cementitious material (hydraulic) - an inorganic material or a mixture of inorganic materials that sets and develops strength by chemical reaction with water by formation of hydrates and is capable of doing so under water (ASTM C125) Hydration Reaction • Reaction of hydraulic cementitious materials with water results in production of calcium silicate hydrates (C-S-H) and calcium hydroxide (CH), also ettringite and other hydrated aluminate phases (C-A-H) • Examples: portland cement, slag cement, Class C fly ash • Hydraulic Reaction: Hydraulic Cement + Water C-S-H + CH • C-S-H provides strength – desirable product • CH provides little strength and is soluble, also is a reactant in many MRD mechanisms – undesirable product 12/3/2020 2 • SCMs consume CH through the pozzolanic reaction • Improves strength • Increases paste density • Reduces alkali (ASR mitigation) • Reduces rate of heat evolution due to hydration reaction • Slower strength development Hydration Reaction: Cement + Water C-S-H + CH Pozzolanic Reaction: Pozzolan + CH + Water C-S-H Pozzolanic Reaction Effects of SCMs on Properly Cured Hardened Concrete Reduced No/Little Effect Fly ash Slag Silica fume Natural PozzolanIncrease Varies Strength Gain Abrasion Resistance Freeze-Thaw and Deicer-Scaling Resistance Drying Shrinkage and Creep Permeability Alkali-Silica Reactivity Chemical Resistance Carbonation Concrete Color Effects of SCMs on Properly Cured Hardened Concrete Reduced No/Little Effect Fly ash Slag Silica fume Natural PozzolanIncrease Varies Strength Gain Abrasion Resistance Freeze-Thaw and Deicer-Scaling Resistance Drying Shrinkage and Creep Permeability Alkali-Silica Reactivity Chemical Resistance Carbonation Concrete Color • Coal Fly Ash • Slag Cement • Silica Fume General Characteristics - Composition Increasing silica Low calcium oxide Pozzolanic Increasing calcium oxide Moderate Silica Hydraulic 12/3/2020 3 General Characteristics – Particle Size & Shape 2 0 m ic r o n s 2 0 m ic r o n s 2 0 m ic r o n s 2 0 m ic r o n s Portland Cement Slag Cement Fly Ash Silica Fume • The finely divided residue that results from the process of combustion of ground or powdered coal and that is transported by flue gasses (ASTM 2015) • Produced from pulverized coal fuel • Fuel stream may have other components such as limestone, trona, other additives for pollution control Coal Fly Ash Coal Fly Ash Production • Airborne residue from coal combustion processes collected from the flue gases by a variety of means • Electrostatic precipitators • Fabric filters (baghouse) Coal Fly Ash Production • Quality and consistency depends in part on burning conditions and fuel sources • An important characteristic of coal combustion fly ash is the presence of residual carbon intermixed with the fly ash • Natural product of combustion – more prevalent in Class F ash • Powder activated carbon (PAC) added to achieve pollution control goals • Not all ash produced is acceptable for use in concrete • Non-spec ash may be useful for other construction applications • CLSM (flowable fill) • Subgrade stabilization 12/3/2020 4 Fly Ash Specification • Fly ash is specified under ASTM C618 (AASHTO M 295) Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete • Chemical Requirements • Classified based on the “sum of the oxides” (SUM) RECENT CHANGE SUM (wt.%) = % SiO2 + % Al2O3 + % Fe2O3 • Class F and Class C SUM ≥ 50% • Class F CaO ≤ 18% (low calcium oxide) • Class C CaO > 18% (high calcium oxide) • Class N SUM ≥ 70% (natural pozzolan source only) Coal Fly Ash Specification Class C Class F Increasing Hydraulic Activity Increasing Pozzolonic Activity Coal Fly Ash Specification Shehata & Thomas, 2002 Shashiprakash and Thomas 2001 McCarthy et al 1990 Coal Fly Ash Specification • Key Physical Requirements • Fineness – amount retained on 325 mesh sieve - Limit of 34% all classes • Strength Activity Index (SAI) – relative strength of a mortar with 80% portland, 20% fly ash compared to control (100% portland cement) - Limit of 75% of control, all classes at 7 or 28 day 12/3/2020 5 Strength Activity Index 75% Specification Limit Strength Activity Index • Strength Activity Index is questioned as it allows inert materials to pass • Experiments performed with non-pozzolanic quartz filler – at 20% replacement they all pass the SAI • Need a new test to measure SCM reactivity Strength Activity Index Coal Fly Ash Characteristics • Benefits • Improved workability • Decreased heat of hydration • Reduced cost • Potential increased sulfate resistance and alkali-silica reaction (ASR) mitigation • Increased late strength, and decreased shrinkage and permeability • Concerns • Air-entraining admixture adsorption by residual carbon in the fly ash • Slow initial strength gain (Class F) • Fly ash variability • How reactive is it? 12/3/2020 6 Fly Ash Carbon Affect on Air Entrainment • Air entraining admixtures (AEAs) • organic compounds used to entrain a controlled amount of air • AEAs typically contain ionic and non-ionic surfactants made of natural sources such as wood resins, tall oil, or synthetic chemicals Schematic view of AEA molecule Head Ionic portion (has a charge) Strong attraction to water (hydrophilic) Tail Non-ionic (has no charge) Little or no attraction to water (hydrophobic) • Hydrophilic, anionic polar groups (i.e. head) sorb strongly to the ionic cement particles • Hydrophobic, non-polar end of the surfactants (i.e. tail) orient towards the solution • Stabilize (entrain) air bubbles, prevent coalescing into larger bubbles Fly Ash Carbon Affect on Air Entrainment • Carbon in fly ash adsorbs AEA from the concrete mix water • Reduces the amount of AEA remaining in the water to a point where the AEA is no longer able to stabilize the required volume of air bubbles Fly Ash Carbon Affect on Air Entrainment • Carbon content in fly ash is estimated by the loss on ignition (LOI) test • Determines the total volatile materials, not just carbon • Test does not characterize the adsorption capacity of the carbon - most important • Two ashes can have the same LOI content but affect air entrainment very differently • Newly developed tests, such as the foam index test, iodine number test, and direct adsorption isotherm test, provide different approaches to measuring ash adsorption (NCHRP 749) Fly Ash Carbon Affect on Air Entrainment 12/3/2020 7 • An emerging issue is the use of powdered-activated carbon (PAC) as an additive in the coal combustion process to adsorb mercury from flue gases • PAC is highly adsorptive • A small amount may not significantly affect the LOI value but can drastically affect the ash adsorption properties • As PAC is more commonly included in coal fly ash, the need for adsorption-based tests and specifications will increase Fly Ash Carbon Affect on Air Entrainment ASR Mitigation with Fly Ash • Class F ash (pozzolanic) best at ASR mitigation • Pozzolanic materials consume CH, reducing hydroxyl ions in pore water, leads to ASR mitigation • Because of the variability in ash properties, it is important to verify an ash’s mitigation potential • Testing Fly Ash Mitigation – all tests are empirical, which means they are based on experience and observation • An empirical test only means something if you do it the same way when testing, as you did when you made the observation and created the test ASR Mitigation with Fly Ash • ASTM C1293 Concrete Prism Test • Currently the most reliable test available – not infallible • Not quick – one year minimum – two years when validating SCM replacement • Known drawbacks include alkali leaching that can lead to errors in estimating the alkali threshold need for ASR to occur 12/3/2020 8 ASR Mitigation with Fly Ash • ASTM C1567 • Accelerated Mortar Bar Test • Based on ASTM C1260 • Cannot be used unless there is a reasonable correlation between C1260 and C1293 for the aggregate in question Alkali-Aggregate Reactivity (AAR) Facts Book. Thomas, M.D.A., Fournier, B., Folliard, K.J. ASTM C1293 Data 0.04% at 2 years Specification Limit ASTM C1567 Data – 14 day (standard) 0.10% at 14 days Specification Limit ASTM C1567 Data – 28 day (non- standard) 0.10% at 14 days Specification Limit 12/3/2020 9 So what’s the problem? The Problem • Fly ash supplies are challenged by plant closures and conversions to natural gas • Fly ash spot shortages have been reported in many U.S. markets • Concerns center on the fact that no other material is available with the reserves that fly ash historically has provided Coal-fired Power Plants are Being Retired Navajo Generating Station • 2250 megawatt net coal- fired powerplant • Largest coal fired electrical generating station west of the Mississippi • Produces approximately 500,000 tons a year of Class F fly ash • Closed 2020 12/3/2020 10 Coal-fired Power Plants are Being Retired Source: U.S. Energy Information Administration, 2019 2020 2035 Ash Production is Dropping So What’s Up With Fly Ash? • Domestic fly ash production (new production) will be gradually decreasing over the next 20 years and beyond • Domestic production is predicted to stabilize (next 5 years) – reductions in coal–fired power will plateau (EIA 2019) • Fewer plants, running at a higher percentage of capacity • Suppliers believe that although total reserves may decrease, the volume of quality ash as a percentage of total production will increase due to dry handling – no more ponding • Harvested ash from landfills/ponds will become a significant fraction of the total reserves 12/3/2020 11 So What Else is Up With Fly Ash? • Other Challenges • Pollution control measures will affect “fresh” ash • Powdered Activated Carbon • Trona • Competing with other markets for the material • Lower supply – consider ash once rejected? • Harvested Ash – A New Frontier Options • What will replace fly ash if needed? • * Slag cement (existing solution) • * Harvested fly ash (emerging solution) • * Ash Imports (emerging solution) • Natural pozzolans (existing solution) • Lower quality fly ash (last resort) • New Materials (colloidal silica, ground glass) • Straight cement Are existing tests and specifications adequate? Slag Cement • Produced from blast-furnace slag (reduction of iron ore) in a blast furnace • Predominately glassy structure with a composition very similar to OPC. • Slag cement is hydraulic and produces calcium silicate hydrate (CSH) as a hydration product hot slag water Slag is changed to glassy sand like substance known as granulated blast furnace slag – GBFS – then ground Graphics used by permission of the Slag Cement Association Slag Cement - Hydration • Slag cement is hydraulic and produces calcium silicate hydrate (C-S-H) as a hydration product • Slag cement reacts slower than portland cement • Hydration of portland cement produces C-S-H and CH • CH reacts with the slag cement, breaking down the glass phases and causing the material to react with water and form C-S-H • Slag cement is not pozzolanic • It does consume CH by binding alkalis in its hydration products • Provides the benefits of a pozzolan 12/3/2020 12 Slag Cement - Specification • ASTM C989 (AASHTO M 302) Standard Specification for Slag Cement for Use in Concrete and Mortars • Classifies the material under three categories: Grade 80, Grade 100, and Grade120 • The grade classification refers to the relative strength of mortar cubes using the SAI test with a 50% replacement of OPC • Uses standard reference cement • 75% of the Control 28-day strength = Grade 80 • 95% of the Control 28-day strength = Grade 100 • 115% of the Control 28-day strength = Grade 120 Slag Cement • Because slag cement reacts slow: • Setting time can be increased significantly compared to OPC concrete • Has lower heat evolution making slag cement ideal for mass concrete placement where control of internal temperatures is critical - up to 80% replacement of OPC with slag cement is used for mass concrete • Curing is essential for all concrete; it is even more critical with slag-cement-based concrete • The slower reaction rate, especially at lower temperatures, is often overlooked, and this can lead to scaling when not properly cured • Slag cement is effective at mitigating ASR • Requires higher replacement rates than Class F ash (e.g., > 50%) Harvested Ash • Significant volumes of high- quality fly ash have been disposed • Approximately 2000 million short tons produced 1974 - 2013 • Approximately 650 million short tons used 1974 – 2013 • ~33% utilization – 1350 million short tons disposed • Not all is recoverable, but a large fraction is Production and Use of Coal Combustion Products in the U.S. ARTBA 2015 20.1 tons used 36.2 tons produced Harvested Ash • With diminishing production, ash marketers are turning to land fills & ash ponds to recover fly ash • Most harvested sources are Class F ash • Limited research to date on performance of harvested ash • All harvested sources will require processing • Drying • Sizing • Blending • Could lead to more uniformity - or less - depending upon source and degree of processing 12/3/2020 13 Harvested Ash • Concerns • Uniformity – ash in ponds will stratify based on density and strata in land fills/ponds will represent different coal sources and burning conditions • Weathering – Does storage alter the chemical or physical nature of the ash? • Adulteration – many land fills/ponds hold bottom ash, scrubber residue, and other wastes in addition to ash • Infiltration – clays and other materials may infiltrate and co-deposit • Testing – do current specifications provide tests & limits that will adequately screen harvested ash? Harvested Ash • Concerns (continued) • Current federal and state regulations require near-term closure of disposal ponds, leaving insufficient time to recover and use all available ash • Power producers have little to no incentive to use ash beneficially, closure (cap-in-place) is the lowest cost option. • Benefits of landfilled ash • Well over a billion tons of ash in disposal • Proper processing could provide a more uniform product • Significant reserves could help limit cost increases although processing will add costs Imported Ash 12/3/2020 14 Coal-fired Power Plants are Being Retired? Source: CarbonBrief Coal-fired Power Plants are Being Retired? Source: CarbonBrief Imports • Certainly in the near term, and potentially long term, imports will become a significant source • Imports are already a significant contributor in some markets • China is COMMITTED to keeping shipping costs low, making imports cost effective (i.e., producing a large number of ocean-going cargo ships at a fraction of the cost of western countries) • For imports. issues of quality must be considered - TESTING 12/3/2020 15 Natural Pozzolans • With issues of availability for other SCMs, natural pozzolans and ASCMs are attracting interest within the industry • Examples of natural pozzolans include • Some diatomaceous earths • Opaline cherts and shale • Tuffs • Volcanic ashes • Pumicite • Various calcined clays and shales • Some natural pozzolans can be used as mined • Most require processing such as drying, calcining, or grinding - TESTING Lower Quality - Increased Need for Testing • So called “off-spec” ash is being considered • Note: Existing ash specifications do not address performance (i.e., meeting the specification does not guarantee performance) • If performance of a material can be demonstrated – use it • Common off-spec issues • LOI • Fineness • Materials that are not coal fly ash are not off-spec; they are simply not fly ash – but they may work • Verify reserves New Materials – Ground Glass • Total Production (~ 11 million tons/year in U.S.) • Container Glass (~ 3 million tons/year in U.S.) • E-Glass (100,000 lbs/year in U.S.) • Recycling capacity exceeds generation (U.S. EPA) • Primary Processing – Grinding • -325 mesh • Composition is uniform 12/3/2020 16 Nominal Glass Composition Soda Lime Glass E-Glass Bottle Glass Plate Glass Display Glass SiO2 71 71 63 60 Al2O3 1.8 0.4 18 12.5 Fe2O3 0.6 0.4 0.0 0.4 B2O3 0.01 0.02 2.0 0.0 MgO 0.90 3.9 2.5 2.9 CaO 11 9.3 0.1 21 Na2O 13 13 13 0.75 K2O 0.5 0.05 0.0 0.06 Bottom Ash • ASTM is discussing a “Class B” for bottom ash • Mimics the properties of the fly ash from the same coal but attributes are subdued, relative to the fly ash • Contributes to concrete properties • Mitigates ASR • Angular – increased water demand • Commonly comingled with fly ash in harvested materials •Green, B. ACI Materials Journal, SP-254-8, 121–132, 2008. •Kudyba-Jansen, A., Hintzen, H., Metselaar, R. Materials Research Bulletin, 36, 1215 – 1230, 2001. Class F Fly Ash Colloidal Silica Colloidal Silica After J. Belkowitz, Intelligent Concrete LLC 12/3/2020 17 Alternative SCMs • Inorganic materials that react, as a pozzolan or hydraulic cement, and beneficially contribute to the strength, durability, workability, or other characteristics of concrete, and do not meet ASTM specifications C618, C989, and C1240 • Examples include some slags or fly ash from co-combustion processes such as coal with biomass • Used in limited applications in some markets • ASTM C1709 Standard Guide for Evaluation of Alternative Supplementary Cementitious Materials (ASCM) for Use in Concrete was developed to provide a clear methodology for evaluating these materials Ternary Mixtures • Concrete mixtures that contain OPC and two other materials in the binder fraction • The binder materials may be combined at the batch plant, or obtained as a pre-blended product • In general, ternary mixtures perform in a manner that can be predicted by knowing the characteristics of the individual ingredients • One benefit of ternary mixtures is that negative properties of a one SCM can be offset by positive properties of another Straight Cement? • 3:5:6 • Once 3:5:6 doesn’t apply (e.g., 6:6:6) the cement replacement advantage is diminished • Sustainability goals are important only if incentivized • A higher cement content (low alkali loading) is not out of reality IF the mixture meets performance • ASR mitigation • Sulfate attack prevention • Physical properties ASR Risk Mitigation - AASHTO 12/3/2020 18 What about tests and specifications? • Existing tests and specifications provide little information on performance • As harvested materials and other sources become more common, new tests and specifications are required that relate to performance (i.e., pozzolanic activity, hydraulic activity, particle size, adsorption) • Need to let go of historic limits/tests established in a completely different concrete world that mean little now (e.g., SAI test, LOI) • Specifications need to include blending SCMs • Need to get more materials in the market while improving performance and quality Trends in Specifications • Concerns with consistent performance & use of harvested ash have caused ASTM & AASHTO to re-evaluate specifications • Measure reactivity (done) • R3 tests (rapid, reliable, reproducible) – measure heat released by isothermal calorimetry or else measure bound water - both for SCM exposed to CH solution • Lime Pozzolanic Activity Test • Particle size – need a better test • Consider modifications to SAI • Measure efficiency Trends in Specifications • Recently removed the Effectiveness in Controlling ASR test & limits • Adsorption potential – just passed the foam index test at ASTM • Use adsorption based tests rather than LOI • Remove Autoclave soundness - nothing fails (pending) • Remove available alkali test - Not required to assess ASR mitigation (pending) • New natural pozzolan specification (pending) • New performance-based specification (pending) 12/3/2020 19 Summary • SCMs are essential to concrete durability • Key materials • Fly Ash • Slag cement • Silica fume • Emerging Materials • Natural pozzolans • Alternative SCMs Summary • All SCMs are expected to favorably affect the following but each does so in varying degrees • Strength • Permeability • Heat of hydration • ASR and Sulfate attack mitigation • SCMs may or may not favorably affect the following • Early strength • Rate of strength gain • Cost Summary • Availability and use of SCMs is changing – fly ash is in short supply in some markets • Traditional material supplies will be challenged • Trends will be towards more ternary mixtures where blends of SCMs will be used • New materials will enter the market place • Testing of all materials and verification of performance in concrete will become more important moving forward Summary • Near term solutions • Other SCMs (e.g., slag, ground glass, natural pozzolans) • Imports • Harvested Ash • Straight cement – possible – durability may suffer if not approached carefully 12/3/2020 20 Questions? llsutter@mtu.edu | ||
| Wet-Weather Strategies for Handling Concrete Placements Exposed To Rain | 👤 Ron Kozikowski | Iowa Better Concrete Conference | 2020 | 2020-11-18 | 12/11/2020 1 Ron Kozikowski, P.E. 1 Ronald Kozikowski is a Professional Engineer, specializing in troubleshooting concrete construction issues. With 20 years of concrete construction industry experience, Ron has been the Vice President of North Starr Concrete Consulting since 2012. Throughout his career, he has developed extensive knowledge and expertise in a broad range of concrete materials related subject matter. Ron is a member and voting member of several industry organizations and is a well-respected and trusted educator having taught and given technical presentations numerous conventions and conferences. He has authored more than 30 technical articles and is co-author on a book focused on topping slab design for the American Society of Concrete Contractors. Ron is licensed in both Illinois and New Hampshire and holds a BS in Civil Engineering and a MS in Materials/Structural Engineering from the University of New Hampshire. Wet-Weather Strategies for Concrete Placements Exposed To Rain Ronald Kozikowski North Starr Concrete Consulting November 18, 2020 2 IOWA Better Concrete Conference • Understand the four main properties of rainstorms and what affect they can have on concrete placements. • Timing of a rainstorm during a concrete placement will influence how the rain event should be handled. Learn what options available to contractors during the main stages of placing and finishing concrete. • Learn what repair options are available if a concrete placement is affected by rain. • Understand what a “wet weather plan” is and what should be included in one. Learning Objectives: Wet-Weather Strategies for Concrete Placements Exposed To Rain Wet-Weather Strategies for Concrete Placements Exposed To Rain 3 Additional Information – Concrete InternationalAdditional Information – Concrete International 4 • For more information see August 2019 article in Concrete International “Concrete Placements Exposed to Rain” 12/11/2020 2 Additional Information – Concrete InternationalAdditional Information – Concrete International 5 • For more information see August 2019 article in Concrete International “Concrete Placements Exposed to Rain” Rainwater vs. BleedwaterRainwater vs. Bleedwater 6 Rainwater vs. Bleed WaterRainwater vs. Bleed Water 7 • Rain and bleed water are similar • Neither will soak back into concrete • Cannot work either into the surface or intermix with the concrete • Must remove both prior to finishing 雨 Properties of Rainstorms Timing Duration Intensity Volume 8 12/11/2020 3 Timing – Most Influential PropertyTiming – Most Influential Property 9 • Most influential factor • Will dictate if rainwater can or cannot be removed prior to finishing • Can be broken down into 4 main stages of a concrete placement Timing – Most Influential PropertyTiming – Most Influential Property 10 Stage 1 Stage 2 Stage 3 Stage 4 Placement Waiting/Dormancy Final Finishing Curing Time S ti ff e n in g Duration – How Long Does It Last?Duration – How Long Does It Last? 11 • Once rain starts, how long does it last? • Timing of a storm may be favorable, but duration could limit or prevent water from being removed Timing – Most Influential PropertyTiming – Most Influential Property 12 Stage 1 Stage 2 Stage 3 Stage 4 Placement Waiting/Dormancy Final Finishing Curing Time S ti ff e n in g 12/11/2020 4 Timing – Most Influential PropertyTiming – Most Influential Property 13 Stage 1 Stage 2 Stage 3 Stage 4 Placement Waiting/Dormancy Final Finishing Curing Time S ti ff e n in g Intensity – How Hard Will It Rain?Intensity – How Hard Will It Rain? 14 • More intense storms increase the potential for washing away surface paste • Contractors may have to consider methods for minimizing washout and/or cushioning blows from rain droplets on the surface Volume – How Much Rainwater?Volume – How Much Rainwater? 15 • Least of the four rainwater concerns • Can pose labor concerns associated with manpower to remove excess water • Large volumes of flowing water can remove surface paste Surface If Rainwater Is Properly HandledSurface If Rainwater Is Properly Handled 16 12/11/2020 5 17 • If rainwater is not properly handled, the following types of damage can occur… Loss of Surface PasteLoss of Surface Paste 18 Loss of Surface PasteLoss of Surface Paste 19 Soft / Weak SurfaceSoft / Weak Surface 20 12/11/2020 6 Soft / Weak SurfaceSoft / Weak Surface 21 Soft / Weak SurfaceSoft / Weak Surface 22 Soft / Weak SurfaceSoft / Weak Surface 23 S.G. = 1.0 Water S.G. > 1.0 Cement SCM Rock Sand Soft / Weak SurfaceSoft / Weak Surface 24 • Standing rainwater will not be absorbed by concrete • If rainwater cannot be removed prior to finishing it could weaken a shallow surface layer • American Concrete Paving Association (ACPA) states rainwater typically affects top 1/8-inch of concrete surface and can be repaired by grinding 12/11/2020 7 Surface MarringSurface Marring 25 Indentations From Rain DropletsIndentations From Rain Droplets 26 Indentations From Rain DropletsIndentations From Rain Droplets 27 Indentations From Rain DropletsIndentations From Rain Droplets 28 12/11/2020 8 Planning and Protection OptionsPlanning and Protection Options • Timing and duration of a rain event is usually unpredictable • Understand situational protection options for the 4 stages of a concrete placement: Placement Waiting / Dormancy Final Finishing Curing 29 STAGE 1 – Concrete PlacementSTAGE 1 – Concrete Placement 30 Stage 1 Stage 2 Stage 3 Stage 4 Placement Waiting/Dormancy Final Finishing Curing Time S ti ff e n in g 31 32 12/11/2020 9 STAGE 1 - OPTIONSSTAGE 1 - OPTIONS • Involves placement, screeding, and floating • ONLY stage where rainwater could get intermixed while workers walk through, consolidate, and strike off concrete • ONLY stage where higher w/c and possibly lower compressive strengths could occur due to intermixing 33 STAGE 1 - OPTIONSSTAGE 1 - OPTIONS • Stop placement • Install emergency bulkhead • Evaluate the affected concrete 34 35 STAGE 2 – Waiting Period / DormancySTAGE 2 – Waiting Period / Dormancy 36 Stage 1 Stage 2 Stage 3 Stage 4 Placement Waiting/Dormancy Final Finishing Curing Time S ti ff e n in g 12/11/2020 10 STAGE 2 – Waiting Period / DormancySTAGE 2 – Waiting Period / Dormancy • A favorable window of time during which rain can occur (typically extends several hours) • Rainwater should be removed prior to final finishing • Rainwater will not be absorbed into the slab • If storm is intense may need to consider methods to minimize loss of surface paste 37 Should Slab Be Covered w/ Plastic?Should Slab Be Covered w/ Plastic? 38 Should Slab Be Covered w/ Plastic?Should Slab Be Covered w/ Plastic? 39 Should Slab Be Covered w/ Plastic?Should Slab Be Covered w/ Plastic? 40 • Obstacles (rebar, blockouts, etc.) can make it hard to cover slab • Sheets not usually wide enough to cover entire slab. Water gets between seams. • Removing plastic and standing water can be challenging • Plastic will trap heat & increase setting time of slab surface. This shortens amount of time to get rainwater off and finish slab. 12/11/2020 11 Removing Water From Surface Is Critical!Removing Water From Surface Is Critical! 41 • Timely removal = success! • Goal – Remove water quickly without removing excess surface paste • Rainwater Removal Equipment Squeegees Rigid polystyrene foam board Garden hose Old compressor hose Large fans Leaf blowers Removing Water From Surface Is Critical!Removing Water From Surface Is Critical! 42 Removing Water From Surface Is Critical!Removing Water From Surface Is Critical! 43 Removing Water From Surface Is Critical!Removing Water From Surface Is Critical! 44 12/11/2020 12 Removing Water From Surface Is Critical!Removing Water From Surface Is Critical! 45 Removing Water From Surface Is Critical!Removing Water From Surface Is Critical! 46 Removing Water From Surface Is Critical!Removing Water From Surface Is Critical! 47 Removing Water From Surface Is Critical!Removing Water From Surface Is Critical! 48 12/11/2020 13 Removing Water From Surface Is Critical!Removing Water From Surface Is Critical! 49 Don’t Forget To Keep Water Off SurfaceDon’t Forget To Keep Water Off Surface 50 Stage 3 – Final FinishingStage 3 – Final Finishing 51 Stage 1 Stage 2 Stage 3 Stage 4 Placement Waiting/Dormancy Final Finishing Curing Time S ti ff e n in g Stage 3 – Final FinishingStage 3 – Final Finishing 52 • Not a favorable time for rain • Slab is rapidly stiffening and minimal protection options are available. • A light rain between passes may be removed but heavy rain during this period may need to be addressed with repair. • Do not mix water into surface • Do no sprinkle dry cement on rainwater 12/11/2020 14 Stage 3 – Final FinishingStage 3 – Final Finishing 53 Stage 3 – Final FinishingStage 3 – Final Finishing 54 Stage 3 – Final FinishingStage 3 – Final Finishing 55 Stage 4 - CuringStage 4 - Curing 56 Stage 1 Stage 2 Stage 3 Stage 4 Placement Waiting/Dormancy Final Finishing Curing Time S ti ff e n in g 12/11/2020 15 Stage 4 - CuringStage 4 - Curing 57 • Most favorable time for rain event to occur • Generally slab has achieved final set after hard trowel passes are complete • Unlikely for washout to occur at this point but finishers may want to have plastic on hand in the event that a very intense rain occurs Rain Slab Repair OptionsRain Slab Repair Options 58 • Unfortunately not all rained-on slabs are successfully finished • If substantial intermixing of rainwater did not occur then damage is usually very superficial (1/8 inch) • Surface repairs are available • Consider depth of damage • Acceptance criteria for final surface appearance • Review Div 9 requirements & investigate what level of surface repair is necessary. Repair Options – Apply Silicate HardenerRepair Options – Apply Silicate Hardener 59 Repair Options – Apply Silicate HardenerRepair Options – Apply Silicate Hardener 60 12/11/2020 16 Repair Options – Apply Silicate HardenerRepair Options – Apply Silicate Hardener 61 Repair Options – Grind SurfaceRepair Options – Grind Surface 62 Repair Options – Bonded Topping SlabRepair Options – Bonded Topping Slab 63 • Proprietary products available for bonded overlays where ½” or less is being restored • Consider placing 4x4 ft mockup for approval and evaluating process Repair Options – Bonded Topping SlabRepair Options – Bonded Topping Slab 64 12/11/2020 17 Repair Options – Bonded Topping SlabRepair Options – Bonded Topping Slab 65 Repair Options – Bonded Topping SlabRepair Options – Bonded Topping Slab 66 67 Repair Options – Bonded Topping SlabRepair Options – Bonded Topping Slab 68 12/11/2020 18 Wet-Weather Protection PlanWet-Weather Protection Plan 69 • ACI 301-16 “Specification for Structural Concrete”, references possible wet-weather plan submittal along with hot and cold weather submittals. Section 5.1.2 Submittals Wet-Weather Protection Plan – SITE ACCESSWet-Weather Protection Plan – SITE ACCESS 70 Wet-Weather Protection Plan – SITE ACCESSWet-Weather Protection Plan – SITE ACCESS 71 Wet-Weather Protection Plan – Material StorageWet-Weather Protection Plan – Material Storage 72 12/11/2020 19 Wet-Weather Protection Plan – Material StorageWet-Weather Protection Plan – Material Storage 73 Wet-Weather Protection Plan – Material StorageWet-Weather Protection Plan – Material Storage 74 Wet-Weather Protection PlanWet-Weather Protection Plan 75 PPE Wet-Weather Protection PlanWet-Weather Protection Plan 76 Stage 1 Stage 2 Stage 3 Stage 4 Placement Waiting/Dormancy Final Finishing Curing Time S ti ff e n in g 12/11/2020 20 Wet-Weather Protection PlanWet-Weather Protection Plan 77 • Plan should include what protection options contractor may utilize during the 4 stages of concrete placement • Plan should include list of equipment & supplies • Discuss plan and proposed procedures during preconstruction meeting. • Discuss potential repairs should the need arise Wet-Weather Strategies for Concrete Placements Exposed to Rain Questions? 78 Iowa Better Concrete Conference Virtual November 18, 2020 | ||
| The New ACI 301-20 | 👤 Michelle Wilson | Iowa Better Concrete Conference | 2020 | 2020-11-11 | 11/4/2020 1 The New ACI 301-20 Presented by: Michelle L. Wilson, FACI Director, Concrete Knowledge Portland Cement Association ACI 301-20, Specifications for Concrete Construction Discussion • Goal of Specifications • ACI Standards and Codes • Defaults • Introduction to ACI 301-20 • How to Reference ACI 301 ACI 301-20, Specifications for Concrete Construction Goal of Specifications •Clear •Single interpretation • List only mandatory requirements •Be written so that it cannot be misunderstood ACI 301-20, Specifications for Concrete Construction Bad Specifications • Confusing • Non-Mandatory • Too Prescriptive 11/4/2020 2 ACI 301-20, Specifications for Concrete Construction ACI 301-20, Specifications for Concrete Construction ACI Committee Reports, Guides, Standard Practices, and Commentaries are intended for guidance in planning, designing, executing, and inspecting construction. This document is intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and who will accept responsibility for the application of the information it contains. ACI disclaims any and all responsibility for the stated principles. The Institute shall not be liable for any loss or damage arising there from. Reference to this document shall not be made in contract documents. If items found in this document are desired by the Architect/Engineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the Architect/Engineer. Industry Guide Documents ACI 301-20, Specifications for Concrete Construction ACI 301-20, Specifications for Concrete Construction Do You Know Your Defaults? US Standards: ACI 318- Building Code Requirements for Structural Concrete ACI 301- Standard Specification for Structural Concrete ACI 311.6 - Specification for Ready Mixed Concrete Testing Services ACI 117- Specifications for Tolerances for Concrete Construction ASTM C94- Standard Specification for Ready-Mixed Concrete 11/4/2020 3 ACI 301-20, Specifications for Concrete Construction Written to Comply with ACI 318-19, CH 26 ACI 301-20, Specifications for Concrete Construction Codes and Standards Umbrella ACI 301-20, Specifications for Concrete Construction Evolution of ACI 301 ACI 301-20, Specifications for Concrete Construction Quest for Perfection • ACI 301-xx 11/4/2020 4 ACI 301-20, Specifications for Concrete Construction Consensus ACI 301-20, Specifications for Concrete Construction 301 Family ACI 301-20, Specifications for Concrete Construction Introducing the New ACI 301-20 ACI 301-20, Specifications for Concrete Construction MasterFormat • Reference specification that is written to Construction Specifications Institute (CSI) Three Part Format: • General • Products • Execution 11/4/2020 5 Legal Document Body of the Specification (53 pages) -The Body of the Specification - Gives direction to the Contractor Checklists Direction to the Specifier (Back pages 53-69) -Mandatory Requirements Checklist -Optional Requirements Checklist ACI 301-20, Specifications for Concrete Construction ACI 301-20, Specifications for Concrete Construction Main Body • Section 1—General requirements • Section 2—Formwork and formwork accessories • Section 3—Reinforcement and reinforcement supports • Section 4—Concrete mixtures • Section 5—Handling, placing, and constructing ACI 301-20, Specifications for Concrete Construction Optional Sections- When Applicable • Section 6—Architectural concrete • Section 7—Lightweight concrete • Section 8—Mass concrete • Section 9—Post-tensioned concrete • Section 10—Shrinkage-compensating concrete for interior slabs • Section 11—Industrial floor slabs • Section 12—Tilt-up construction • Section 13—Precast structural concrete • Section 14—Precast architectural concrete ACI 301-20, Specifications for Concrete Construction Mandatory Requirements Checklist F4. The Mandatory Requirements Checklist indicates Work requirements regarding specific qualities, procedures, materials, and performance criteria that are not defined in ACI Specification 301-20. The Specifier must include these requirements in the Project Specification. 11/4/2020 6 • Trigger language- ‘specified in Contract Documents’ - Items requires the Specifier to take action f’c aggregate size tolerance of mesh reinforcement - Designate specialty sections scope ie: What portions of project are architectural concrete , mass concrete, or post-tensioned. Mandatory Requirements Checklist ACI 301-20, Specifications for Concrete Construction ACI 301-20, Specifications for Concrete Construction Optional Requirements Checklist F5. The Optional Requirements Checklist identifies Specifier choices and alternatives. The Checklist identifies the Sections, Parts, and Articles of the ACI Reference Specification 301-20 and the action required or available to the Specifier. The Specifier should review each of the items in the Checklist and make adjustments to the needs of a particular project by including those selected alternatives as mandatory requirements in the Project Specification. ACI 301-20, Specifications for Concrete Construction New Title- Define Scope ACI 301-20, Specifications for Concrete Construction Section 1- General Requirements, Definitions and Tolerances • Scope • Definitions • References- ACI, ASTM, Other Industry Documents • Testing 11/4/2020 7 ACI 301-20, Specifications for Concrete Construction • New definitions included for clarity. • Definitions of specialty concrete applications were removed. • A/E’s must designate portions of work meeting special applications such as architectural concrete or mass concrete. Definitions ACI 301-20, Specifications for Concrete Construction • Optional Checklist • Review • Project Requirements • Acceptance Criteria • Responsibilities Preconstruction Conference ACI 301-20, Specifications for Concrete Construction Internal Curing • ASTM C1761 ACI 301-20, Specifications for Concrete Construction Shotcrete • ACI 506.2 • ACI 318-19 11/4/2020 8 ACI 301-20, Specifications for Concrete Construction Section 2- Formwork and Formwork Accessories • Design and Construction • Movement Joints and Waterstops • LDE Optional or Mandated by Jurisdiction • Tolerances- ACI 117-10 ACI 301-20, Specifications for Concrete Construction Section 3- Reinforcement and Reinforcement Supports • Materials, Fabrication, and Placement • WWR • Tolerances- ACI 117-10 ACI 301-20, Specifications for Concrete Construction Zinc-Coated (Galvanized) Reinforcing Bars • 318-19 bars in accordance with ASTM A767/A767M • Lesser thickness permitted in accordance ASTM A1094/A1094M ACI 301-20, Specifications for Concrete Construction Section 4- Concrete Mixtures • Materials, Mixture Proportioning, Production, and Delivery • Specify f’c • Exposure Class • Durability Requirements 11/4/2020 9 ACI 301-20, Specifications for Concrete Construction Self-Consolidating Concrete • Requirements for Slump Flow • Passing Ability- ASTM C1621 • Static Segregation- ASTM C1610 ACI 301-20, Specifications for Concrete Construction Minimum Cementitious Requirements ACI 301-20, Specifications for Concrete Construction Prequalification of Aggregates • ASTM C33 • Alkali Aggregate Reactivity- ASR and ACR • ASTM C1293 • ASTM C1567 • ASTM C1260 • ASTM C1778 ACI 301-20, Specifications for Concrete Construction • Recycled Aggregates are permitted (ASTM C33) if documentation is provided suitable to A/E. • Mineral Fillers conforming to ASTM C1797 New Materials 11/4/2020 10 ACI 301-20, Specifications for Concrete Construction • Test Data • 318-19 Modulus of Elasticity ACI 301-20, Specifications for Concrete Construction Durability Exposure Classifications • Sulfate Exposure Categories • Chloride limits ACI 301-20, Specifications for Concrete Construction Section 5- Handling, Placing, and Constructing • Construction Requirements for cast-in Place Concrete • Handling, Placing, Finishing, Curing • Repair of Surface Defects ACI 301-20, Specifications for Concrete Construction Cold Weather • Temperature of Massive Metallic Embedded Items ≥ 10˚F • Contact Surface Temperature ≥ 32˚F 11/4/2020 11 ACI 301-20, Specifications for Concrete Construction Curing by Ponding • Temperature of Ponding Water Must be at Least ≥ 50˚F • Not More than 35˚F Cooler Than Surface Contact Temperature ACI 301-20, Specifications for Concrete Construction High Strength Concrete • Integrate HSC with Floor Systems • Extend at Least 2 ft Past Face of Columns and Walls • Achieve a Monolithic Mass ACI 301-20, Specifications for Concrete Construction Surface Finish Requirements • SF-2 is Default Finish • Exposed to View • Finish requirements updated ACI 301-20, Specifications for Concrete Construction Adhesive Anchor Requirements • Horizontally or Upwardly Inclined Holes • 21 Day Old Concrete • Installed by ACI Certified Adhesive Anchor Installers 11/4/2020 12 ACI 301-20, Specifications for Concrete Construction Section 6- Architectural Concrete • Mandatory Preconstruction Conference • Mock Ups • Technical Specialists ACI 301-20, Specifications for Concrete Construction Formwork for Architectural Concrete • Structurally Rated Plywood Bonded to Sanded Hardwood Veneer • NonPorous Finished Surface ACI 301-20, Specifications for Concrete Construction Section 7- Lightweight Concrete • Meet Equilibrium Density- ASTM C567 • Density Tolerances ±4 lb/ft3 ACI 301-20, Specifications for Concrete Construction Section 8- Mass Concrete • Thermal Control Plan • Maximum Temperature and Temperature Difference • DEF 11/4/2020 13 ACI 301-20, Specifications for Concrete Construction Thermal Control Plan • Cementitious Material Restrictions Removed • Allows Changes to Materials Without Updates ACI 301-20, Specifications for Concrete Construction Section 9- Post-Tensioned Concrete • Structural Design of PT • LDE ACI 301-20, Specifications for Concrete Construction Encapsulated Tendons • Non-Encapsulated Tendons Prohibited • Slabs on ground exposed to external sources of chlorides • Stressing pockets are subject to wetting or direct contact with soil • Cutting of Tendons ACI 301-20, Specifications for Concrete Construction Section 10- Shrinkage-Compensating Concrete for Interior Slabs • Cementitious Materials- ASTM C845 • Reinforcement Requirements • Isolation Joints • Expansion Test Results- ASTM C878 11/4/2020 14 ACI 301-20, Specifications for Concrete Construction Section 11- Industrial Floor Slabs • Drying Shrinkage Test Results- ASTM C157 ACI 301-20, Specifications for Concrete Construction Joint Fillers • 100% Solids • Shore A Hardness of at least 85%- ASTM D2240 • Elongation below 90%- ASTM D638 ACI 301-20, Specifications for Concrete Construction Section 12- Tilt-up Construction • Mock Ups • 2 Panels, at least 4 ft x 8 ft • Lifting and Bracing Design Drawings ACI 301-20, Specifications for Concrete Construction Smooth Panel Finishes • SPF-2 Finish Required • Visibility of Panels • Repair Scope and Method 11/4/2020 15 ACI 301-20, Specifications for Concrete Construction Sections 13 and 14- Precast Structural Concrete and Precast Architectural Concrete • Aligned with PCI • MNL-116 and MNL-117 • Erector QC, Plant QC • Fabricators Qualifications ACI 301-20, Specifications for Concrete Construction Fabricator Qualifications • Alternative Certification Program from NPCA • Applicable to Structural Precast Products (non prestressed) ACI 301-20, Specifications for Concrete Construction How to Reference ACI 301 • Work on (Project Title) shall conform to all requirements of ACI 301-20, “Specifications for Structural Concrete,” published by the American Concrete Institute, Farmington Hills, Michigan, except as modified by these Contract Documents. This is not sufficient! Must also handle Mandatory Checklist and consider Optional Checklist within Contract Documents Read ACI 301-20 • Avoid Confusion • Know what’s written • Do you know your defaults? ACI 301-20, Specifications for Concrete Construction 11/4/2020 16 Be Clear on Desired Outcome Specifications should have the right “hoops” to jump through to get the performance required for service conditions. Use ACI 301 ACI 301-20, Specifications for Concrete Construction Further Information Michelle L. Wilson Director, Concrete Knowledge mwilson@cement.org www.cement.org ACI 301-20, Specifications for Concrete Construction | ||
| A Scale of Two Cities | 👤 Dan Goldsworth 👤 Mark Stinocher 👤 Jordan Stokes 👤 Nick Aldrich | Iowa Better Concrete Conference | 2020 | 2020-12-16 | 12/17/2020 1 Project Bluejay (Bondurant) and Krause Gateway Center (Des Moines) A Scale of Two Cities 1 22 Agenda 1. Ryan Introductions 2. Project Bluejay 3. Krause Gateway Center 4. Q&A 3 About Ryan – Midwest Profile Jordan Stokes Self Performed Work Project Manager Nick Aldrich Senior Project Manager Mark Stinocher Concrete Superintendent Dan Goldsworth Senior Superintendent 12/17/2020 2 Project Bluejay Project Bluejay • Longest concrete pumping was 900’ off of the pump. 750’ slick line and 150’ rubber • SOG and SOMD simultaneously typically 900- 1000 yds on deck, 1400-1600 on ground • Winter conditions challenges to overcome • Sequencing changes due to Amazon early access dates • Achieving these pours with a rotating man- power team as they all traveled • Mesh install crew, install 50,000 to 60,000 sq ft per day. Concrete Summary Bollards 40.50 Column 169.00 Curb 269.50 Footing 6,328.50 Interior Piers 9005.50 Interior SOG 15,990.00 Paving 17,802.50 Retaining Walls 252.00 SOMD 33,816.00 Stem Walls 1,814.00 Stoops 34.50 Walks 3,388.00 TOTAL: 88,910.00 12/17/2020 3 2nd Floor - Steel Floor Pour sequence map SOG. Pour Map 12 Line Anchor Bolts 12/17/2020 4 SOD. # 3 rebar welded @ 4’’ X 4’’ Ready for Concrete Fun Facts • Started on Oct.16, 2019 • Substantial complete Sep. 29, 2020 • First SOD. Pour 4th. Floor 3-11 To last Interior Pour 5-16 • 67 Calendar days 3,000,000 SF. • CSI Partnered with Norwalk Concrete. • 10 Foot Candle of light required for all pours Pouring SOD 12/17/2020 5 12 Line Expansion Joint Installing Fu duchies on 2nd - 4th SOG. Dock Pit Pour SOG. Pour. 12/17/2020 6 Diamond Dowels Polished Breakroom floors Front Entry West Truck Parking 12/17/2020 7 Questions Krause Gateway Center Krause Gateway Center • Broke ground in 2015; Completed in 2018 • 6-story building; 164,000 SF • 225-stall 2-story underground parking • Designed by internationally renowned architect Renzo Piano Building Workshop (Genoa/Paris/New York) • Architect-of-Record: OPN Architects • Over 55 design consultants and subcontractors Self Perform Work • Jordan • Jordan • Jordan 12/17/2020 8 Krause Gateway Center • Natural, abundant light throughout the building • Collaborative work environments • Outdoor meeting space • Rooftop plaza sized for over 700 people • Green Roof with native prairie plants • Fitness room and adjoining locker room • Game room • Art collection Krause Gateway Center • Over 65,000 cubic yards of material has been excavated from the site • Over 4,000 tons of Structural Steel • 1,400 Steel Penetrations • 29’ tall x 4’ wide glass panels • 100’ tall mast on top of the building • LEED Certification (Registered) 12/17/2020 9 Self Performed Work • Normally run around 100 skilled tradesman in the field – between Carpenters, Finishers, and Laborers – this last year we peaked our skilled trade labor at 223 • Concrete • Carpentry • Structural and Finish Demo of Existing Spaces KGC – Concrete Scope • Foundations – Columns – Grade Beams – Pile Caps – Foundation Walls – 32’-0’’ tall in parking garage • Architectural Finished Concrete walls – similar to precast finish • Slab on Grade • Mild Reinforced concrete decks (parking ramp area) • Slab on Metal Deck (building levels) • Topping slabs on all levels • Exterior Site concrete – Sidewalks – Exposed aggregate with a ground finish Challenges • Working through constraints with the building itself. Overhangs made it difficult to complete “normal” concrete pours. • Tasked with producing “perfect” cast-in-place walls with the visual characteristics of pre- cast based only on photos of past project. • Site logistics –tight and highly visible site that takes up a small city block. It is always a challenge to make sure all work is coordinated. FOUNDATIONS 12/17/2020 10 Foundation Plan Parking Garage Foundations Core Mat Slab Stats • Five hour duration • Two concrete pumps • 627 cubic yards of concrete • 63 trucks of concrete material • 39,763 LF (7.5 miles) of rebar • 35.5 tons of rebar Core Foundation Plan 12/17/2020 11 Core Mat Slab Core Mat Slab PARKING GARAGE Walls and Columns 12/17/2020 12 Core Structural Deck Pour Shear Key Shear Key 12/17/2020 13 BUILDING FLATWORK Topping Slab Prep Slab-on-Deck Heat Tube Slab-on-Deck Pour 12/17/2020 14 ARCHITECTURAL CONCRETE WALLS Concrete Wall Mock Up Precast Mock Up Architectural Walls Architectural Walls 12/17/2020 15 Architectural Walls Architectural Walls Architectural Walls Architectural Walls 12/17/2020 16 Architectural Walls Debossed Sign SITE FLATWORK Site Flatwork 12/17/2020 17 Site Flatwork East Exterior Stair East Exterior Stair Site Flatwork - Mockup 12/17/2020 18 Site Flatwork Site Flatwork MOCK-UPS Slab on Grade Mock Up 12/17/2020 19 Steel Nosing Mock Up Glass Mock Up Wood Wall Mock Up Ceiling Mock Up 12/17/2020 20 Restroom Mock Up WE BUILD STORIES | ||
| 27th Annual Iowa Chapter ACI Excellence in Concrete Construction Awards | 👤 Steve Mallicoat 👤 Jerod Gross | Iowa Better Concrete Conference | 2020 | 2020-12-02 | 1 27th Annual Excellence in Concrete Awards Agricultural Above-Grade Buildings Low-Rise Buildings Mid-Rise Buildings Commercial/Industrial Decorative Parking Areas/Drives (<1,000 CY) Parking Areas/Drives (>1,000 CY) Infrastructure - Recreational Categories Infrastructure – Structures Recreational Trails Residential Above-Grade Homes Residential Decorative Streets and Intersections Infrastructure – Bridges Sustainable Practices Categories 2 Judges Brian Bartlett, frk architects & engineers Brant Bristow, Tometich Engineering, Inc. Natalie Carran, SB&A Architects Clay Schneckloth, Snyder & Associates, Inc. Matt Ferrier, Bolton & Menk Jerod Gross, Snyder & Associates, Inc. Todd Fonkert, Bremer County Engineer - Retired John Goode – Monroe County Engineer – Retired Denny Osipowicz, Lee County Engineer – Retired Thomas Parsons, ICPA-IRMCA Steve Mallicoat, ICPA-IRMCA Agricultural FIVE STAR COOPERATIVE NEW HAMPTON CROELL, INC. Agricultural OWNER Five Star Cooperative DESIGNER/GENERAL CONTRACTOR Empire Ag, LLC ENGINEER KC Engineering, P.C. 3 FIVE STAR COOPERATIVE FIVE STAR COOPERATIVE FIVE STAR COOPERATIVE Croell, Inc. FIVE STAR COOPERATIVE Five Star Cooperative 4 Above-Grade Buildings FAIRFIELD INN & SUITES DAVENPORT MANATT’S, INC. Above-Grade Buildings OWNER & GENERAL CONTRACTOR Heart of America Group CONCRETE SUBCONTRATOR Hidden Valley Builders, Inc. ICF SUPPLIER Fox Blocks ENGINEER Schaefer Structural Engineers FAIRFIELD INN & SUITES FAIRFIELD INN & SUITES 5 FAIRFIELD INN & SUITES Manatt’s, Inc. FAIRFIELD INN & SUITES Heart of America Group FAIRFIELD INN & SUITES Fox Blocks Low-Rise Buildings PIVO EVENT CENTER CALMAR CROELL, INC. 6 Low-Rise Buildings OWNER/GENERAL CONTRACTOR Craig Neuzil CONCRETE SUBCONTRACTOR Northeast Iowa Spray Foam & Construction, LLC DESIGNER Sara Neuzil PIVO Event Center PIVO Event Center PIVO Event Center Croell, Inc. 7 PIVO Event Center Craig & Sara Neuzil PIVO Event Center Northeast Iowa Sprayfoam & Const., LLC Mid-Rise Buildings ISU STUDENT INNOVATION CENTER AMES CONCRETE SUPPLY, INC. Mid-Rise Buildings OWNER Iowa State University GENERAL CONTRACTOR JE Dunn CONCRETE SUBCONTRACTOR Ceco Concrete Construction ARCHITECT/DESIGNER Kieran Timberlake ENGINEER Saul Enginering 8 ISU STUDENT INNOVATION CENTER ISU STUDENT INNOVATION CENTER ISU STUDENT INNOVATION CENTER Concrete Supply, Inc. ISU STUDENT INNOVATION CENTER Iowa State University 9 Commercial/Industrial Decorative JAMIE HURD AMPHITHEATER WEST DES MOINES CONCRETE SUPPLY, INC. Commercial/Industrial Decorative OWNER City of West Des Moines GENERAL CONTRACTOR Henkel Construction Company CONCRETE SUBCONTRACTOR Nehring Construction, Inc. ARCHITECT/DESIGNER OPN Architects, Inc. ENGINEER Raker Rhodes Engineering, LLC JAMIE HURD AMPHITHEATER JAMIE HURD AMPHITHEATER 10 JAMIE HURD AMPHITHEATER Concrete Supply, Inc JAMIE HURD AMPHITHEATER City of West Des Moines Parking Areas/Drives (<1,000 CY) HIDDEN CREEK MULTI-USE ANKENY CONCRETE SUPPLY, INC. Parking Areas/Drives (<1,000 CY) OWNER/DESIGNER Hunziker Development GENERAL CONTRACTOR Hunziker Construction Services CONCRETE SUBCONTACTOR Hetzler & Rhodes Concrete Construction ENGINEER Snyder & Associates, Inc. 11 HIDDEN CREEK MULTI-USE HIDDEN CREEK MULTI-USE HIDDEN CREEK MULTI-USE Concrete Supply, Inc. HIDDEN CREEK MULTI-USE Hunziker Development and Hunziker Construction Services 12 HIDDEN CREEK MULTI-USE Hetzler & Rhodes Concrete Construction Parking Areas/Drives (>1,000 CY) FLEET FARM CEDAR RAPIDS CROELL, INC. Parking Areas/Drives (>1,000 CY) OWNER & GENERAL CONTRACTOR Lloyd Companies CONCRETE SUBCONTRACTOR K & M Concrete Construction ARCHITECT/DESIGNER RSP Architects ENGINEER ISG FLEET FARM – CEDAR RAPIDS 13 FLEET FARM – CEDAR RAPIDS FLEET FARM – CEDAR RAPIDS Croell, Inc. FLEET FARM – CEDAR RAPIDS Lloyd Companies Infrastructure –Recreational MASON CITY MULTI-PURPOSE ARENA CROELL, INC. 14 Infrastructure -Recreational OWNER City of Mason City GENERAL CONTRACTOR Dean Snyder Construction ICE ARENA SUBCONTRACTOR Rink-Tec International, Inc. ARCHITECT/DESIGNER ICON Architectural Group ENGINEER WHKS MASON CITY MULTI-PURPOSE ARENA MASON CITY MULTI-PURPOSE ARENA MASON CITY MULTI-PURPOSE ARENA Croell, Inc. 15 MASON CITY MULTI-PURPOSE ARENA City of Mason City Infrastructure – Structures & Sustainable Practices RED ROCK HYDROELECTRIC PROJECT KNOXVILLE MANATT’S, INC. OWNER Missouri River Energy Services GENERAL CONTRACTOR Ames Construction ARCHITECT / ENGINEER Stantec Infrastructure – Structures & Sustainable Practices RED ROCK HYDROELECTRIC PROJECT 16 RED ROCK HYDROELECTRIC PROJECT RED ROCK HYDROELECTRIC PROJECT Manatt’s, Inc. RED ROCK HYDROELECTRIC PROJECT Missouri River Energy Services Infrastructure - Bridges IA 1 OVER CAMP CREEK LATERAL SLIDE KALONA CROELL, INC. 17 GENERAL CONTRACTOR Peterson Contractors, Inc. CONCRETE SUBCONTRACTOR Streb Construction Co., Inc. ARCHITECT/DESIGNER Iowa DOT Bridges & Structures Bureau ENGINEER Iowa DOT District 5 Office Infrastructure - Bridges IA 1 OVER CAMP CREEK LATERAL SLIDE IA 1 OVER CAMP CREEK LATERAL SLIDE IA 1 OVER CAMP CREEK LATERAL SLIDE Croell, Inc. 18 IA 1 OVER CAMP CREEK LATERAL SLIDE Streb Construction Co., Inc. IA 1 OVER CAMP CREEK LATERAL SLIDE Iowa Department of Transportation Recreational Trails GEAR AVENUE TRAIL IDEAL READY MIX CO., INC. Recreational Trails OWNER City of West Burlington GC / CONCRETE SUBCONTRACTOR Jones Contracting Corp. ENGINEER Snyder & Associates, Inc. 19 GEAR AVENUE TRAIL GEAR AVENUE TRAIL GEAR AVENUE TRAIL Ideal Ready Mix Co., Inc. GEAR AVENUE TRAIL City of West Burlington 20 GEAR AVENUE TRAIL Jones Contracting Corp. Residential Above-Grade Homes LEWIS RESIDENCE SIOUX CITY STANDARD READY MIX CONCRETE CO. Residential Above-Grade Homes OWNER/GENERAL CONTRACTOR Al Lewis CONCRETE SUBCONTRACTOR Prenger Construction ICF SUPPLIER LiteForm ENGINEER Schroder Engineering LEWIS RESIDENCE 21 LEWIS RESIDENCE LEWIS RESIDENCE Standard Ready Mix Concrete, Co. LEWIS RESIDENCE Al & Kathy Lewis LEWIS RESIDENCE LiteForm 22 Residential Decorative SCHARNBERG BARN ST. CHARLES CONCRETE SUPPLY, INC. Residential Decorative OWNER Mark Scharnberg GENERAL CONTRACTOR Eick & Day Construction, LLC CONCRETE SUBCONTRACTOR Amstutz Concrete, LLC ARCHITECT/DESIGNER SVPA Architects, Inc. ENGINEER Tometich Engineering SCHARNBERG BARN SCHARNBERG BARN 23 SCHARNBERG BARN Concrete Supply, Inc. Streets and Intersections 35TH/36TH ST. AVE L PROJECT FORT MADISON IDEAL READY MIX CO., INC. Streets and Intersections OWNER City of Fort Madison GC/CONCRETE SUBCONTRACTOR Jones Conctracting Corp. DESIGNER / ENGINEER HR Green, Inc. 35th/36th ST. AVE L PROJECT 24 35th/36th ST. AVE L PROJECT 35th/36th ST. AVE L PROJECT Ideal Ready Mix Co., Inc. 35th/36th ST. AVE L PROJECT City of Fort Madison 35th/36th ST. AVE L PROJECT Jones Contracting Corp. 25 Thank you! | ||
| Durable Concrete in a Low-Ash World | 👤 Jerod Gross 👤 Dan King | Concrete Lunch & Learn | Fall 2020 |
| 2020-11-02 | Durable Concrete in a Low-Ash World Jerod Gross, PE, LEED AP Dan King, PE Representing the CP Tech Center What’s Coming Up… A Virtual Better Concrete Conference Noon webinars Nov. 4 ACI 301 – Specifications for Concrete Construction Michelle Wilson, PCA Nov. 18 Wet Weather Strategies for Handling Concrete Placements Ron Kozikowski, North Starr Concrete Consulting Dec. 2 The Future of Fly Ash: Dystopia or Hysteria Larry Sutter, Michigan Tech University Dec. 16 Project Bluejay & Krause Gateway Center Dan Goldsworth, Mark Stinocher, Jordan Stokes, Nick Aldrich https://register.gotowebinar.com/register/6780190539906386191 2 https://register.gotowebinar.com/register/6780190539906386191 Special Thank you Dr. Peter Taylor, PE, Ph. D Director, National Concrete Pavement Technology Center ptaylor@iastate.edu 3 mailto:ptaylor@iastate.edu Overview • Introduction • Controlled mixtures • Other products • Impacts in Iowa • Crystal ball gazing 4 Presenter Presentation Notes To start off, we will give a background on fly ash. What is it, what is it good for, how is it used? Then we will discuss controlled mixtures, local impacts and looking to the future Introduction • Fly ash is amazing! • Less expensive $ • More workable • Reduces permeability • ASR / sulfate / oxychloride resistant • Cooler (lower heat of hydration) • But… • There are no fly ash factories • Utilities are changing • 2020… 5 Presenter Presentation Notes This image is from Dr. Taylors first professional conference in 1987. Fly ash is not just a waste product, it is a valuable resource. Not cheaper… less expensive. They take the place of cement 15-30% and have similar properties of cement More workable – sometimes challenging for tall curbs Reduces permeability Helps treat ASR, sulfate reaction , oxychloride resistant Production of fly ash is slowing down Particulates and contaminants that used to go up through the flume are captured and combined with the ash, so quality has changed over the years Cementitious Materials 6 Hydraulic cement – reacts with water, creates CH Pozzolan – reacts with cement and water, consumes CH Portland Cement Slag Cement Class C Fly Ash Class F Fly Ash Silica Fume Not to scale Cement F Fly Ash C Fly Ash Slag Silica fume Metakaolin CaO Al2O3 SiO2 Presenter Presentation Notes Definitions! HC = Material that sets and hardens by a series of nonreversible chemical reactions with water, a process called hydration. Portland cement = a specific type of hydraulic cement. Pozzolan = material that reacts with cement and water in ways that improve microstructure. SCM = cements and pozzolans other than portland cement Silica fume is pure pozzolan Class C is a little of both, but slightly more hydraulic Calcium Oxide (lime), silica oxide, Aluminum are 3 main ingredients as shown in upper right figure Class C is most common in Iowa pavements… Chart1 21.1695098703 70.7254079757 55.3944177195 39.153638945 56.4799176381 83.5955077264 11.5470053838 23.0940107676 34.6410161514 46.1880215352 34.6410161514 11.5470053838 23.0940107676 46.1880215352 103.9230484541 92.3760430703 80.8290376865 69.2820323028 0 103.9230484541 92.3760430703 80.8290376865 69.2820323028 69.2820323028 23.0940107676 46.1880215352 92.3760430703 92.3760430703 69.2820323028 46.1880215352 23.0940107676 57.735026919 115.4700538379 0 0 0 CaO Al2O3 SiO2 Cement F Fly Ash C Fly Ash Slag Silica fume Metakaolin ca1 ca2 ca3 ca4 sa3 sa1 sa2 sa4 cs1 cs2 cs3 cs4 Frame Cement 23.3333333333 65 47.2972972973 40.2298850575 97.8260869565 55.2083333333 20 40 60 80 60 20 40 80 20 40 60 80 0 20 40 60 80 0 0 0 0 0 0 0 0 100 0 0 Sheet1 Absolute Calcium oxide Silica Alumina Iron oxide Total CSA Cement 63 21 6 2 90 F Fly Ash 5 52 23 11 80 C Fly Ash 21 35 18 6 74 Slag 40 35 12 1 87 Silica fume 2 90 0 0 92 Metakaolin 0 53 43 1 96 another 1 1 1 0 3 Corrected Cement 70 23 7 F Fly Ash 6 65 29 C Fly Ash 28 47 24 Slag 46 40 14 Silica fume 2 98 0 Metakaolin 0 55 45 another 33 33 33 Y axis X axis Si 1/root3*(Si-2(100-Ca)) Cement 23 21 F Fly Ash 65 71 C Fly Ash 47 55 Slag 40 39 Silica fume 98 56 Metakaolin 55 84 another 33 58 Sheet1 11.5470053838 23.0940107676 34.6410161514 46.1880215352 34.6410161514 11.5470053838 23.0940107676 46.1880215352 103.9230484541 92.3760430703 80.8290376865 69.2820323028 0 103.9230484541 92.3760430703 80.8290376865 69.2820323028 69.2820323028 23.0940107676 46.1880215352 92.3760430703 92.3760430703 69.2820323028 46.1880215352 23.0940107676 57.735026919 115.4700538379 0 0 0 CaO Al2O3 SiO2 Cement F Fly Ash C Fly Ash Slag Silica fume Metakaolin ca1 ca2 ca3 ca4 sa3 sa1 sa2 sa4 cs1 cs2 cs3 cs4 Frame Cement 20 40 60 80 60 20 40 80 20 40 60 80 0 20 40 60 80 0 0 0 0 0 0 0 0 100 0 0 Sheet2 CS X Y Ca Si Al 1/root3*(Si-2(100-Ca)) 100 0 0 0 0 80 20 0 12 20 60 40 0 23 40 40 60 0 35 60 Boundary 20 80 0 46 80 0 0 0 100 0 58 100 0 100 0 0 SA 0 0 Ca Si Al X Y 0 0 100 115 0 0 20 80 104 20 0 40 60 92 40 0 60 40 81 60 0 80 20 69 80 0 100 0 58 100 CA Ca Si Al X Y 100 0 0 0 0 80 0 20 23 0 60 0 40 46 0 40 0 60 69 0 20 0 80 92 0 0 0 100 115 0 Sheet3 Fly Ash Production • By-product of combustion of pulverized coal • During combustion • Volatiles & carbon burned off • Mineral impurities remain in flue gas • Fused materials cool into glass spheres 7 Presenter Presentation Notes No fly ash factories! We depend on power! We have figured out how to burn low quality coal. Grind coal very small (flour consistency), blow air into furnace with the coal and still get good efficiency. Fine powder burned at high temperatures, very fine powder melts the rock, tiny spherical balls go up the flue, captured the waste on filters or electrostatic precipitators, the waste is cooled quickly that makes it glassy. Three properties: 1) Glass, 2) calcium silica alumina, 3) very small Fly Ash Contaminants • Carbon (LOI) • Sucks up air entrainers • Sulfates • Expansion • Moisture • Handling, workability • C3A • Can contribute to incompatibility 8 Hwang, Sun, Li Presenter Presentation Notes Contaminants Carbon - Image is unburned carbon transported out with the fly ash. Very porous, huge surface area so it sucks up air entrainers. With low quality ash, we have harder time entraining air with high carbon content. Measuring carbon is somewhat difficult so we have the term LOI (loss of ignition.) How much mass is lost when igniting (burning carbon) now burning other materials so LOI isn’t the best measurement any more. Not a 1:1 relationship anymore Looking for alternative ways to measure the effect of fly ash with air entrainers Sulfates – high lime systems tend to have high sulfate. Moisture – if there is any water left in the system, it can effect workability. mixes can get sticky With High calcium ashes (class C ash with lots of lime) may be in the form of tri-calcium aluminate C3A. This can contribute to incompatibility and can accelerate flash set. Specs are important ASTM C618. Need to watch for contaminants. CH How SCMs Work 9 Cement Water React C-S-H CH https://iowadot.gov/research/reports/Year/2007/fullreports/MLR-05-02.pdf Presenter Presentation Notes Important – modern cements produce more CH which can be addressed with the SCM . CH is flaky crystalline structure Easy to break a flat crystal (CH is not very strong) CH is reasonally soluable Faster curing concrete, industry has ground into finer particles, this has increased CH Calcium Hydroxide • Good for raising pH and protecting steel • Bad for • Oxychloride • Solubility • Shear strength 10 CH Presenter Presentation Notes CH is great for raising pH 13-14 range Calcium oxychloride is a bad thing. Forms and stable at relatively cool weather (above 32 degrees) Expands at 300%. 30 times the amount of water when it freezes CH How SCMs Work 11 Cement Water React C-S-H CHWaterSCM React C-S-H Presenter Presentation Notes Gray text in reaction arrow means slows the hydration Introduction • Can we go back to this? 12 Presenter Presentation Notes Can we just leave out the fly ash? No, we have been there done that. Introduction • Review the benefits 13 Hover 2020 Workability • Does workability matter to anybody other than the contractor? • “Add 10” • Hurts long term performance • The right vibration • How fast, how long • Moves air, water and aggregates • Aesthetics • Matter to the owner • Fly ash and admixtures help 14 Presenter Presentation Notes Excess vibration moves air upwards, moves water horizontally. (not good for structural applications) Photo is from Route 5 Need uniform distribution of aggregate and uniform air min. 5% Durability • Durability is largely governed by permeability / transport • Most failure mechanisms involve water • Getting low permeability • Low water/cement (MN history) • Appropriate SCM dose 15 Presenter Presentation Notes MN DOT led the charge for low w/cm 0.38-0.4 Far more durable concrete SCM helps by densifying the system and tying up the CaOxy Oxychloride • MgCl2 and CaCl2 • React with CaOH to form calcium oxychloride • Forms when temperature >32 ºF • Expands ~300% • Unstable at higher temperatures • Prevented by using SCMs to reduce 16 CH Presenter Presentation Notes Some researchers say we need 30-35% SCM 20% ash seems to work and is practical amount. Review • What do we (really) need from fly ash • ASR • Oxychloride • Permeability • Workability • Strength • Heat • Sustainability • Cost 17 Limited alternatives to fly ash Alternatives available Presenter Presentation Notes States like Michigan that pay attention to ASR does not have oxychloride because they use F ash There are alternative ways to getting Perm, workability, strength, heat 1% increase in cost Sustainability may come into play in the future. More important to get durable pavement now. So lets design our mixtures for what you need .. Next slide Controlled mixtures • Prepare the mixture for the application • Use what you need (and no more) • From what you have • Control the cementitious content 18 Controlled mixtures • Use what you need (and no more) • Its like balancing the family checkbook • ASR – depends on the aggregate • Oxychloride – depends on the cement • Permeability • Workability • Strength • Heat • Sustainability 19 Limited alternatives Alternatives available True or False? • More cement = more strength • Strength is everything • Slump indicates quality • Stronger concrete is more “brittle” 20 Controlled mixtures • Control the cementitious content • With more cement you need more fly ash • Excess has a: • Negative effect on permeability, shrinkage, cost • Small negative effect on strength • “Optimum” depends on: • Aggregate type • Gradation 21 How do we proportion to achieve design goals? 22 Workability Transport Strength Cold weather Shrinkage Aggregate stability Aggregate System Type, gradation - - - - Paste quality Air, w/cm, SCM type and dose Paste quantity Vp/Vv - - - - Presenter Presentation Notes This chart indicates which of the three mixture parameters affects what critical property. The yellow stripe is where the specification should reside. All else should be left to the contractor to match available materials with their equipment while still meeting spec requirements. Controlled mixtures • From what you have • Class C or F • Behave differently 23 Cement F Fly Ash C Fly Ash Slag Silica fume Metakaolin CaO Al2O3 SiO2 Other Products • Slag cement • Metakaolin • Other minerals like zeolite? • Microspheres for f/t protection • IP cements • But… 24 Sutter But • Do they do what we need? • They change mix properties • Cost • Particularly shipping • Is it worth it? • Availability • “Free market?” 25 But • Education • Every product has its own quirks • Specifications • Have to be appropriate • AASHTO PP84 • Iowa • DOT: QM-C • SUDAS: C-SUD 26 AASHTO PP84 • Require the things that matter • Transport properties (everywhere) • Aggregate stability (everywhere) • Strength (everywhere) • Cold weather resistance (cold locations) • Shrinkage (dry locations) • Workability (everywhere) 27 AASHTO PP84 • Measure them at the right time • Prequalification • Process control • Acceptance • A buffet of approaches • Prescriptive: w/cm, paste volume • Performance: Formation factor 28 AASHTO PP84 • Allow contractor to develop the mixture to meet requirements • w/cm (within limits) • SCM dose (within limits) • Aggregate gradation • Iowa’s QM-C and C-SUD mix specs are informed by these principles 29 Payne Presenter Presentation Notes And are changing for the better Measuring what we need • ASR • Follow AASHTO R80 / ASTM C1778 • Oxychloride • LTDSC • Expansion at 40°F 30 Measuring what we need • Permeability / Transport • Resistivity • Strength • Heat • Calorimetry • Air void system • SAM 31 Measuring what we need • Workability • VKelly • Box Measure the response to vibration 32 • Likely to continue seeing reduced fly ash production • Events in 2020 causing a short-term supply crunch: • Mild winter • COVID-19 • Other issues • Consistency • Substitutes are not immediately available 33 Fly Ash in Iowa • What can we do right now with our Iowa mixes to maximize durability? • Save the fly ash for where you need it • The C-SUD mix specification can be used regardless of fly ash content • Follow good principles (control the paste): • Lower total cementitious content via optimized gradation • Appropriate w/cm • Good air void system 34 Iowa Specifications The Future • Blended ashes • “Good enough for engineering purposes” • Coming soon to Iowa? • Reclaimed ash • Quality control • Transportation 35 Sutter 2020 • Reclaimed ash • CP Tech Center September 2020 Tech Brief: • Fly ash harvesting is being done in PA, SC, and WI, and should continue to expand 36 The Future The Future • Local powders • Limited availability • Testing can be onerous (ASTM C 1709) • But all help is good help • Economics may be helping 37 Philosophical Ramblings • What about those old pavements? • Cements have changed • Placement methods have changed • Curing!!!!! • Traffic has changed • Salting has changed 38 Philosophical Ramblings • Life is changing – we have to adapt • There are solutions • We have to think • Quality matters • Call us if you need help Dan King 515-963-0606 dking@concretestate.org Jerod Gross 515-669-7644 jgross@snyder-associates.com 39 mailto:dking@concretestate.org mailto:jgross@snyder-associates.com Durable Concrete in a �Low-Ash World What’s Coming Up… Special Thank you Overview Introduction Cementitious Materials Fly Ash Production Fly Ash Contaminants How SCMs Work Calcium Hydroxide How SCMs Work Introduction Introduction Workability Durability Oxychloride Review Controlled mixtures Controlled mixtures True or False? Controlled mixtures How do we proportion to achieve design goals? Controlled mixtures Other Products But But AASHTO PP84 AASHTO PP84 AASHTO PP84 Measuring what we need Measuring what we need Measuring what we need Fly Ash in Iowa Iowa Specifications The Future The Future The Future Philosophical Ramblings Philosophical Ramblings Slide Number 40 | |
| Concrete Roundabout Design and Construction | 👤 Eric Ferrebee 👤 Steve Waalkes | Concrete Pavement Technology Tuesday Webinar | 2020 |
| 2020-10-20 | 1 Roundabout Design and Construction Eric Ferrebee, P.E. Director of Technical Services ACPA | eferrebee@acpa.org Steve Waalkes, P.E. Director of Engineering MCA | swaalkes@miconcrete.net Concrete Pavement Versatility Why Roundabouts Anyway? According to FHWA: Up to 90% reduction in fatalities 76% reduction in injury crashes 30-40% reduction in pedestrian crashes 75% fewer conflict points than 4-way intersections 30-50% increase in traffic capacity No signal equipment to install/maintain No left-turn lane and reduced need for storage lanes Where are Concrete Pavements Historically Used? Answers: High traffic areas Areas with lots of turning movements Situations where we need a “long-term fix” Situations where future maintenance must be kept to an absolute minimum Areas where future disruption to traffic must be kept to a minimum Economical over long-term – Life-Cycle Cost (LCC) Areas where safety is a priority – surface characteristics 2 Things to Consider for all Intersections and Roundabouts Thickness Jointing Spacing Type Layout Constructability and MOT Other: Drainage Reconstruction versus inlay Subgrade and subbase requirements Thickness Design for Intersections and Roundabouts Pavement Thickness Design AASHTO 1993 Pavement Design Guide Pavement ME Design (MEPDG) Implemented in many states Under calibration in many other states Concrete Pavement Industry Method PavementDesigner.org Developed for Street & Local Road Design REGARDLESS OF METHOD MUST CONSIDER CUMULATIVE TRAFFIC!! Thickness Impacts Jointing! Class ADT ADTT Thickness Light residential < 200 2-4 4.0-5.0 in. Residential 200-1,000 10-50 5.0-6.0 in. Collector 1,000-8,000 50-500 5.5-8.0 in. Business 11,000-17,000 400-700 6.0-8.0 in. Industrial 2,000-4,000 300-800 6.5-9.5 in. Arterial (minor) 4,000-15,000 300-600 6.5-9.5 in. Arterial (major) 4,000-30,000 700-1,500 7.0-10.0 in. Design may be based on AASHTO, PavementDesigner, etc. 3 Concrete Intersections and Roundabouts: Thickness Physical Area Functional Area Concrete Intersections and Roundabouts: Thickness Physical Area Functional Area Low ADTT (T1) Low ADTT (T1) High ADTT (T3) T2 T3 T3 + 0.5 to 1 in. Physical Area Thickness Roadway 1 Low ADTT (T2) High ADTT (T3) High ADTT (T3) Roadway 2 T3>T2>T1 Basic Principles for Jointing and Joint Layout Joint Spacing “Best Practices” Summary Keep it Short! Keep it Uniform! Keep it Perpendicular! Keep it Simple! Keep it Practical! 4 Rules for Joint Layout Things to Do Match existing joints or cracks – location AND type! Cut joints at the proper time and to the proper depth Place joints to meet in-pavement structures Remember maximum joint spacing Place isolation joints where needed Understand that joint locations can be adjusted in the field! Be Practical Type Location Rules for Joint Layout Things to Avoid: Slabs < 2 ft wide Slabs > 15 ft wide Angles < 60º (90º is best) Use “dog-leg” joints through curve radius points Creating interior corners “Odd” shapes Keep slabs nearly square or rectangular, when possible Additional Step by Step Guidance 6 Step Method for Roundabouts http://wikipave.org/index.php?title=Joint_Layout Joint Layout for Roundabouts 5 Layout Joints as Normal Intersection Good for small roundabouts or traffic circles? Jointing Decide on joint layout philosophy Like normal intersection Isolate circle from legs Pave-through, isolate two legs Other philosophy, based on experience Follow 6-step method Joints in circular portion radiate from center Joints in legs are normal (perpendicular) 6-STEP METHOD FOR JOINTING ROUNDABOUTS Concrete Roundabout Design And Construction http://wikipave.org/index.php?title=Joint_Layout Jointing a Roundabout Step 1: Draw all pavement edges and back-of-curb lines in plan view. 6 Jointing a Roundabout Step 2: Draw all lane lines on the legs and in the circular portion, accounting for roundabout type. Jointing a Roundabout Step 3: Add “transverse” joints in the circle, being mindful of the maximum joint spacing. Example – Isolated Truck Apron Jointing a Roundabout Step 4: On the legs, add transverse joints where width changes occur. 7 Jointing a Roundabout Step 5: Add transverse joints between those added in Step 4, minding the maximum joint spacing. Doglegs Layout Joints as Normal Good for small roundabouts or traffic circles? Jointing a Roundabout Step 5: Add transverse joints between those added in Step 4, minding the maximum joint spacing. 8 Jointing a Roundabout Step 6: Make adjustments for in-pavement objects, fixtures, and to eliminate odd shaped slabs. Properly Jointed Roundabout What If I Have to Dead-end a Joint? Dead-End Joint with Roundabouts 9 What If I Have to Dead-end a Joint? What If I Have to Dead-end a Joint? What If I Have an Odd Shaped Slab? Concrete Intersections: Jointing Box Out Fixture Details 10 If You DO Box Out Properly…Good Results Happen! If You DON’T Box Out Properly…Bad Things Happen! Where There’s a Will, There’s a Way… Old…BUT NO CRACKS! 11 Good Practice… Lining joints perpendicular to pavement edge! Alternate Design Examples for Roundabouts Dealing With Traffic Calming and Flare Outs Kansas – Oval Shaped 12 Wisconsin – Pinwheel Method https://wisconsindot.gov/rdwy/sdd/sd-13c18.pdf#page=1 Minnesota – Fiber Reinforced Jointless Report: http://dot.state.mn.us/mnroad/nrra/structure-teams/rigid/files/frc-roundabout-task-1-construction-report-final.pdf Minnesota – Fiber Reinforced Jointless Netherlands – Continuously Reinforced W.A. Kramer, Cement&BetonCentrum G. Jurriaans, ECCRA Guidelines for Concrete Roundabouts in The Netherlands 13 More Information? “Concrete Pavement Field Reference: Prepaving,” EB237P, ACPA, 2007. “Concrete Roundabouts: Rigid Pavement Well-Suited to Increasingly Popular Intersection Type, “ R&T Update #6.03, ACPA, June 2005. “Roundabouts: An Informational Guide,” FHWA-RD-00-068, FHWA, March 2000. “Kansas Roundabout Guide”: http://www.ksdot.org/burTrafficEng/Roundabouts/Roundabout_Guide/RoundaboutGuide.asp Various agency standards…KS, WI, IA, OH, etc… Acknowledgements: Thanks to all ACPA Chapter / State Paving Associations and CPAM and MCA for various slides and photos throughout Thanks to Bill Cuerdon, Todd LaTorella, Kevin McMullen, and Matt Zeller Resources http://wikipave.org Thank You! Next Up: Roundabout Construction Steve Waalkes, P.E. Director of Engineering MCA | swaalkes@miconcrete.net Eric Ferrebee, P.E. Director of Technical Services ACPA | eferrebee@acpa.org 10/23/2020 1 Concrete Roundabout Construction • Joint Layout Plan • Bring up Pavement Markings Layer/Level in CAD • Coordinate joint layout with traffic engineers •Maintenance of Traffic • Field Engineering • Contractor Joint Layout; Must match MOT/staging/phasing Concrete Roundabout Jointing •Develop a jointing plan • Bird’s eye view •Remember rules •Follow the steps •Be practical! •Allow for field adjustments 2 2-Lane Pinwheel 4 10/23/2020 2 3-Lane Directional (pour diagram) Joint Layout – Pencil and Paper MDOT Contractor Joint Layout Special Provision Cass Avenue Roundabouts - Construction Issues •Construction of Concrete Roundabouts Under Traffic • Plan Your Stages Carefully • Partner with Contractor! • Development of Paving Plan • Pavement Widths • Elevations • Cross Section • Joint Layout 10/23/2020 3 Maintenance of Traffic Concept Designs Exp. Joints Isolating Roundabout 10/23/2020 4 M-5 Roundabout at Pontiac Trail, Commerce Township, Oakland County, 2011 ‐10“ non reinforced concrete ‐ Doweled in the roundabout ‐ Three lanes ‐ Constructed in three stages. M-5 & Pontiac Trail 60,000 ADT 10/23/2020 5 Field Engineering Field Engineering What not to do… 10/23/2020 6 What not to do… What not to do… What not to do… • Joint Types need to match! Thank You! swaalkes@miconcrete.net 616-633-9629 Resiliency Webinar – Questions and Answers – 10/20/2020 The questions submitted during the webinar follow with answers that our speakers have provided. Resources: • Joint Layout - Including 6-Step Method for Roundabouts • Jointing Concrete Pavements • Concrete Roundabouts - ACPA Research and Technology Update • EUPAVE’s Concrete Roundabouts Publication • Roundabout Guide from Kansas DOT 1. Noticed on one of the plan sheets a note for a "distribution slab." What is that? Oklahoma The distribution slab in the example from Kansas would also be termed a sleeper slab. This allows two sections of concrete to be isolated from one another and reduce the differential deflection between the two by increasing the support. A from that example is below. 2. Could you please explain more about the importance of aspect ratio? Iowa The aspect ratio of transverse to longitudinal joint spacing is a way of evaluating the slab dimensions. An aspect ratio of 1.25 would mean that the spacing between transverse joints is 1.25 times longer than the longitudinal joint spacing. A typical spacing between longitudinal joints is a 12 ft lane width. So assuming an aspect ratio of 1.25 would mean the transverse joint spacing is 15 ft. We recommend trying to maintain an aspect ratio of 1.25, and not to exceed 1.5. Larger aspect ratios result in a greater risk of cracking within the slab because of higher stresses. http://wikipave.org/index.php?title=Joint_Layout http://wikipave.org/index.php?title=Joints http://1204075.sites.myregisteredsite.com/downloads/RT/RT6.03.pdf https://www.eupave.eu/wp-content/uploads/eupave-concrete-roundabouts.pdf http://www.ksdot.org/burTrafficEng/Roundabouts/Roundabout_Guide/RoundaboutGuide.asp 3. Have you had any evidence that dowel bars lockup as the radius of the circular roadway decreases? Nebraska This concern has been raised, but I have not seen examples of it in the field. If this is a concern, one possible solution would be to use plate dowels or diamond dowels that allow for multi-directional movement. These types of dowels are more common in the industrial market where two-directional doweling is a little more common. 4. Do you have any experience with using plate dowels for roundabouts (and/or standard intersections)? Pennsylvania The concept of using plate dowels and diamond dowels for intersections and roundabouts has been raised, however I do not have photos or specific examples in the field. The benefit of using some plate dowels and diamond dowels is that they allow for two directional movement of the slabs and should be less likely to lockup a joint (see previous question for a little more discussion on this). 5. What is the practice for truck aprons, dowel or do not dowel? Pennsylvania The decision to dowel or not dowel the truck apron is usually on a case-by-case basis and should include a consultation with the geometric designer. With a smaller diameter roundabout, more/most of the trucks will need to utilize the truck apron, and once you approach 80 to 100 trucks per day, dowels are recommended. With a larger diameter roundabout, hopefully fewer trucks will need to use the truck apron, and dowels may be overkill. However, in most cases the initial cost to dowel this area is quite small compared to the overall budget for a roundabout project and is usually a good idea if either of both of the intersecting roadways have significant amounts of heavier truck traffic. 6. What is the recommendation for texturing a roundabout? Pennsylvania Since most roundabouts are low speed, a heavy burlap or broomed texture is common. Artificial turf drag has also been used. Although not required due to the low speeds involved, a few roundabouts have utilized a tined texture. 7. Eric: It would be great if you could share more pictures and info of the CRCP roundabout in the Netherlands. I look into this in the past and I recall that we only had one CRCP roundabout in the US (Texas). I believe CRCP roundabout is attractive because the joint design should be simpler since we only have terminal joints. California EUPAVE (the European Concrete Paving Association) has a roundabout publication that shows some additional photos and details on CRCP roundabouts. There’s also a report on the Dutch Practice of CRCP Roundabouts. https://www.eupave.eu/wp-content/uploads/eupave-concrete-roundabouts.pdf https://www.eupave.eu/wp-content/uploads/eupave-concrete-roundabouts.pdf http://crcpavement.org/wp-content/uploads/2015/08/9th-Stet-Roundabouts.pdf http://crcpavement.org/wp-content/uploads/2015/08/9th-Stet-Roundabouts.pdf There have been a few CRCP roundabouts done in Texas. There was recently a presentation given at ACPA’s Annual Meeting that covered a couple of these. There are definitely some benefits to using a CRCP roundabout as it provides a long- term, low-maintenance pavement that should handle significant truck traffic for a very long time. The cost-benefit should of course be evaluated using best engineering practices and a Life-Cycle Cost Analysis. 8. Are there criteria that will help the designer select the type of roundabout - whether isolated circle, pave-through or pinwheel? Iowa The decision on the type of roundabout joint layout is best left to the overall project engineer in consultation with the traffic engineer and geometric designer. If the “contractor joint layout” option is used, the contractor’s submittal requires approval by the project engineer prior to starting concrete placement. That said, the pinwheel option is quickly becoming popular with many engineers. Contractors will usually live with whatever joint layout is decided upon, subject to field modifications for constructability. 9. What type of base material (if any) is recommended to be placed under the truck apron? Florida The same base material that is under the rest of the roundabout pavement should extend into the middle under the truck apron. 10. Steve: Do you ever run into issues with "contractor joint layouts" when agency/engineer require changes and increased costs, i.e. additional joints, dowels, tie bars, etc? Kansas In Michigan, projects with concrete intersections (including roundabouts) are bid with the following bid items at a minimum: square yards of X inch concrete pavement, lineal feet of transverse doweled joints, lineal feet of tied sawcut longitudinal joints, lineal feet of tied edge-formed longitudinal joints, and lineal feet of plain sawcut plane-of-weakness joints. So the contract will have prices for these items, even if the engineers are off on some of their quantities. In many cases, the engineer still produces a joint layout for their own quantity determination purposes and does not publish it in the plan set released for bid. So to answer your question, there are times when an agency requires changes that were not considered beforehand, and items need to be added to the bid. There is a standard process for this that is followed that controls the allowable price ranges. But most projects have the flexibility to increase some item quantities and/or decrease others without significant cost to the project as a whole. http://www.acpa.org/wp-content/uploads/2016/12/2-Halsted-ACPA-CRCP-Innovations-12.01.16-Halsted.pdf http://www.acpa.org/wp-content/uploads/2016/12/2-Halsted-ACPA-CRCP-Innovations-12.01.16-Halsted.pdf http://www.acpa.org/wp-content/uploads/2016/12/2-Halsted-ACPA-CRCP-Innovations-12.01.16-Halsted.pdf 11. Eric: In the Kansas example it looked like the wheelpaths were at a longitudinal joint because of the way the lanes were striped. Is that a concern for roundabouts or is it unavoidable? Texas We do want to avoid placing longitudinal joints in the wheel paths whenever possible. In some cases where the longitudinal joints can’t match up with lane stripes, they may be placed within the lane, but it is still recommended to keep them out of the wheel path if possible (especially with heavy truck traffic). 12. What is the purpose of the flat section on the inner radius of some of the roundabout examples shown? Nebraska Mountable truck apron. This allows articulated semi-trucks (think WB-50 or WB-53 in geometric design terms) the ability to navigate the relative tight turn radius of a roundabout, with the front wheels staying on the main roundabout pavement while the rear wheels of the trailer sweep across the truck apron. 13. What is the filling material of the core at the dead-end joint? Quebec The fill material can be a weak sand mortar mixture or joint sealant material if the hole is smaller. 14. What volume of truck traffic typically determines whether asphalt or concrete would be best utilized for a roundabout? Oregon AND Is there any guidance out there to select concrete roundabout or asphalt roundabout? California Concrete can be used for any roundabout regardless of what the traffic is. Concrete can be used for nearly any pavement facility. The selection of the paving material should be done with good engineering judgement, design, and should use a life-cycle cost analysis (the subject of next month’s CPTech Webinar) to help make a decision. Having alternate paving alternatives creates more competition that can reduce costs for both paving materials. More information on this concept will be discussed in the LCCA webinar and can also be found on MIT’s Concrete Sustainability Hub website. 15. It seems to be that the public perception of roundabouts is often negative, especially when first installed. Is that something that you have found goes away when the public gets more used to using them or how do you deal with negative public opinion? Iowa Public perception and reaction is generally resistant to any change to the norm. Public outreach and effective communication help to get public buy-in to a project. Typically, with changing an intersection to a roundabout will receive some resistance until the decision is explained or until it has been in place long enough for the public https://cshub.mit.edu/pavements to get used to the change. Oftentimes the negative perception wears away as drivers get used to the new intersection. 16. Are there any dowels at the joints? Florida Dowels are typically used in roundabouts, especially when there is a decent amount of truck traffic. 17. Need good communication with the Inspectors as well as the contractor! Florida Yes! Good communication between all parties on the project is essential for achieving project success. 18. Please define the terms you used: Rutting and shoving. Florida Rutting and shoving are distresses that are often seen in asphalt pavements, especially at intersections and roundabouts that see significant truck traffic. 19. In the dead-end treatment with a hole, how is the hole sealed? Do we use concrete or joint fillers? Minnesota The fill material can be a weak sand mortar mixture or joint sealant material if the hole is smaller. 20. Please explain what isolation joint is. Is this the same as expansion joint? Do we seal that type of joint? Minnesota Many people call isolation joints expansion joints. ACPA uses the term isolation joint to differentiate it from expansion joints used for bridges. A short ACPA publication discusses the difference. These joints are often sealed as well. You can find more information on this on WikiPave’s Jointing page as well as in ACPA’s Joint Sealing technical bulletin. 21. Have you studied the effects of joints that do not complement pavement markings at 2x2 multi-lane roundabouts? Isolated circle jointing seems okay/preferable for single- lane roundabouts, however, can lead to improper lane changing at multi-lane exits due to outer lane vehicles following the joint instead of exiting. Same with Pave-through unless it is a 2x1 RAB lane configuration. For 2x2 the pinwheel pattern seems beneficial to have the jointing complement the pavement markings to reinforce proper lane use. Texas AND It is important to consider how joint patterns can influence driver perceptions of lane geometry, particularly in wet weather. Especially at a multi-lane roundabout, the https://pavementinteractive.org/reference-desk/pavement-management/pavement-distresses/rutting/ https://pavementinteractive.org/reference-desk/pavement-management/pavement-distresses/corrugation-and-shoving/ https://pavementinteractive.org/reference-desk/pavement-management/pavement-distresses/corrugation-and-shoving/ http://metiebar.acpa.org/Downloads/Is400.pdf http://metiebar.acpa.org/Downloads/Is400.pdf https://wikipave.org/index.php?title=Joints http://www.acpa.org/wp-content/uploads/2019/04/Jointing-Sealing-Tech-Bulletin-TB010-2018.pdf http://www.acpa.org/wp-content/uploads/2019/04/Jointing-Sealing-Tech-Bulletin-TB010-2018.pdf isolated circle method differs from the MUTCD pavement marking patterns, and doing so can lend an air of legitimacy to the most common driver errors at multi-lane roundabouts, such as illegal left turns from the outer lane(s). Pinwheel patterns keep the joints in conformance with the MUTCD lane configurations. Michigan and Wisconsin I think have been national leaders in this area. MN The pinwheel joint pattern was developed in Michigan in 2005 primarily for this reason - to appease the concern of traffic engineers with regard to the influence of joint patterns on driver behavior. More important, however, is proper signage and pavement markings. Joint patterns can enhance but do not override these aspects, but they can help function as lane markers in wet weather. Anecdotal evidence from around the country shows that all types of joint patterns can work for most situations, given the proper geometric design, sign type and placement, and pavement markings. Most roundabouts, regardless of pavement type, require some tweaking of signs and pavement markings after they are opened to traffic. 22. Do you have any jointing examples for Turbo Roundabouts? Oklahoma No. Turbo-roundabouts are still a fairly new concept as the first one was constructed around 2000 in the Netherlands. So far there are only about 400 of these type of roundabouts with most being built in the Netherlands (http://www.turboroundabout.com/turbo-roundabout.html). The FHWA Safety Program has released an Informational Primer on Turbo Roundabouts for more details. As this is a fairly new concept in the U.S., we currently don’t have any jointing examples, but would encourage anyone interested in building one in concrete to reach out to your local ACPA Chapter or ACPA National for help in developing a joint layout. 23. What are common designs for the curb and gutter? Can you go with no curb or gutter and just have a shoulder on the outside? We are having issues with larger tractors in ND. North Dakota Curb and gutter profiles range from taller (6”+) barrier curb, to 3” or less mountable curb, flat gutter, and 18” wide to 4’+ wide sections, tied and untied to the concrete pavement, and everything in between, including granite slabs in the Northeast. Local preference usually prevails here. Concrete roundabouts can accommodate many if not all of these types. The main concerns to remember are that curb & gutter functions as a path for drainage, a guide to motorists, and edge support for the concrete pavement. If you decide not to use curb and gutter and will have heavy (tractor) loads at the free edge, the pavement thickness can easily be designed for this, and usually only requires an extra inch vs. tied curb and gutter. Concrete shoulder also functions as edge support just like curb and gutter and can work just fine in a more rural concrete roundabout situation. http://www.turboroundabout.com/turbo-roundabout.html https://safety.fhwa.dot.gov/intersection/innovative/roundabouts/docs/fhwasa20019.pdf Resiliency Webinar – Questions and Answers – 10/20/2020 | |
| Resiliency and Resilient Pavement Systems | 👤 Tom Van Dam 👤 Jim Mack 👤 Gordon Smith | Concrete Pavement Technology Tuesday Webinar | 2020 |
| 2020-09-28 | 1 So What Is Going On With Pavement Resiliency? Thomas Van Dam, Ph.D., P.E., FACI September 22, 2020 What Do You Need to Know About Pavements and Resiliency? • Pavements are important • The climate is changing – Temperatures • Hotter for longer – Wetter in some places, drier in others • Climate change is leading to sea- level rise – Coastal flooding • Other changes https://www.fhwa.dot.gov/pavement/sustaina bility/hif15015.pdf Pavements are Designed for Climatic Conditions • Material selection for range of temperatures – Freezing and thawing – Rutting of asphalt pavements • Moisture condition of unbound subgrade, subbase, and base • Our understanding is at best mechanistic- empirical and based on historic data – Afterall, it is an empirical world 2 Pavements of the Future Need to Be Designed for Future Conditions • Resistant to increasing temperatures • Resistant to increased levels of saturation https://www.epa.gov/climate-indicators/climate-change-indicators- heavy-precipitation Future Needs • Pavements will need to be more robust – This means more costly • Must be close coordination between regional climate modelers, planners, and engineers – Identify critical links, evaluate risk, and make critical links that are vulnerable less so Who Are The Stakeholders? • Agencies – Local, State, and Federal agencies – Those in charge of resource allocation need to incorporate climate change into the decision-making process • Current pavement design and management tools are “looking backwards” • Consultants – The ones conducting planning studies and design – Need to get up to speed with the changing environment • The public – They are the ones most directly affected FHWA Sustainable Pavements Program • In Year 9 of 10-year effort • Many products available and more under development – https://www.fhwa.dot.gov/pavement/sustainability/ • The Sustainable Pavements Technical Working Group (SPTWG) meets twice a year – Next meeting (virtual) Nov. 9, 2020 (become a friend) 3 FHWA Resiliency Efforts • Pavement resiliency peer-exchanges – Two to be held (virtually) on Oct. 6th & 7th and Dec 16th & 17th – Report will be available early next year – Conduct a one-day workshop (optional) • Develop and publish final document • Conduct webinar Wish Us Luck Thomas Van Dam, Ph.D., P.E., FACI Principal tvandam@ncenet.com 702-852-3060 (o) 775-527-0690 (c) Questions? 9/28/2020 1 IMPROVING PAVEMENT RESILIENCY & DISASTER RECOVERY A Case for Concrete Pavements Jim Mack, P.E. Director of Market Development – Infrastructure September 2020 - 2 - TOPICS COVERED The Need for Resilient Pavements Defining Resiliency Improving a Pavement’s Resiliency - 3 - INCREASE OF DAYS WITH HEAT INDEX > 90 F DEGREES BY 2050 Many cities will experience a month or more sweltering days each year. Sources: • https://www.nationalgeographic.com/environment/2019/07/extreme-heat-to-affect-millions-of-americans/#close: • Killer Heat in the United States: Climate Choices and the Future of Dangerously Hot Days, Union of Concerned Scientists, July 2019 - 4 - THE NUMBER OF EXTREME HEAT DAYS WILL INCREASE DRAMATICALLY Urban Areas exposed to 30 or more days with a heat index > 105 F degrees Compared with just 3 urban areas historically Extreme heat will not occur in isolation. There will also be droughts, wildfires, floods, and other extreme weather events that will compound the impacts of the heat Sources: • https://www.nationalgeographic.com/environment/2019/07/extreme-heat-to-affect-millions-of-americans/#close: • Killer Heat in the United States: Climate Choices and the Future of Dangerously Hot Days, Union of Concerned Scientists, July 2019 Midcentury No Action (150+ Urban Areas) Midcentury Slow Action (80+ Urban Areas) Cities Experiencing Heat Index >105°F 9/28/2020 2 - 5 - INCREASED TEMPERATURES CREATE OTHER CLIMATE RISK Risk can occur as both sudden shocks & long-term recurring chronic pressures Airports Rail Roads River Seaports Wildfires Sea-level rise & tidal floods Riverine & pluvial flooding Hurricanes, typhoons & storms Tornadoes & wind events Drought Heat (air & water) Little or No Risk Increased Risk Source: McKinsey & Company, Will infrastructure bend or break under climate stress?, McKinsey & Company, August 19, 2020 https://www.mckinsey.com/Videos/video?vid=6180836320001&plyrid=HkOJqCPWdb&aid=A21DD0A9-7DA8-44A2-87E0-B4944177F295 Climate risk increases operating costs & exacerbates the infrastructure funding gap Transportation Asset - 6 - WARMER SUMMERS WILL AFFECT THE ABILITY TO WORK OUTDOORS In extreme cases, this could put human lives at risk. Sources: • https://www.nationalgeographic.com/environment/2019/07/extreme-heat-to-affect-millions-of-americans/#close: • Killer Heat in the United States: Climate Choices and the Future of Dangerously Hot Days, Union of Concerned Scientists, July 2019 Extreme Heat Days - 7 - EXTREME FLOOD EVENTS ARE INCREASING IN BOTH FREQUENCY AND MAGNITUDE Source: https://www.epa.gov/climate-indicators Change in Magnitude of U.S. River Flooding, 1965–2015 Frequency of Flooding Along U.S. Coasts, 2010–2015 vs 1950–1959 - 8 - NORTH CAROLINA HAS BEEN HIT BY TWO 500 YEAR FLOOD EVENTS Hurricane Matthew (2016) & Hurricane Florence (2018) I-95 Lumberton, NC (2016) I-95 Lumberton, NC (2016) I-40 Pender County 4-Days post hurricane (2018) With Hurricane Florence, NC had over 2500 road closures 9/28/2020 3 - 9 - HOUSTON TEXAS HAS BEEN HIT BY 4 FLOOD EVENTS IN THE LAST SEVERAL YEARS – THE WORST WAS HURRICANE HARVEY - 10 - HURRICANE SALLY IS THE LATEST STORM TO HIT THE USA But it will not be the last Flooded streets, Hurricane Sally Pensacola, Florida on September 16, 2020. - 11 - At one point, the Nebraska DOT reported 1,500 road miles were closed RIVER FLOODING IN THE PLAIN STATES HAS BEEN SEVERE THE LAST SEVERAL YEARS 2018 - 12 - SEA LEVEL RISE IS ALREADY IMPACTING COASTAL ZONES Sunny sky flooding is becoming a common or daily occurrence SR54 East of Fenwick, DE South Bowers Beach , DE DE Photos courtesy of Jim Pappas, DELDOT FL Photos courtesy of Amy Wedel, FC&PA Miami, FL Miami, FL 9/28/2020 4 - 13 - EXTREME HEAT INCREASES THE INCIDENCE OF LARGE FOREST FIRES The number of fires has increased with high statistical significance in 7 out of 10 western US States 1 • Warmer & drier conditions • Increased pest populations • Increased land management practices • Increased fire suppression practices Denser vegetation (increased fuel) Contributing Factors 1. USGCRP, 2018: Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II: 2. Patrick Gonzalez, UC Berkeley forest ecologist and climate change scientist, https://www.capradio.org/articles/2020/09/03/wildfires-in-california-will-continue-to-get-worse-climate-change-experts-explore-why/ “Outdated policies and human-caused climate change [have] increased burn area [by] 900% across the western U.S. since 1984” - 14 - 2020 IS THE WORST YEAR ON RECORD FOR FOREST FIRES More than 85 large wildfires are ripping across the West Coast California – more than 3.2 million acres have burned Oregon – 46 large fires burned more than 1 million acres between Sept 7 – 13. • Double the state's average of 500,000 acres burned annually Washington - over 500,000 acres have burnt in seven days, • Twice the state's total from all of 2019. https://www.insider.com/west-coast-wildfires-map-of-biggest-fires-color-coded-2020-9#:~:text=More%20than%2085%20large%20wildfires,California's%20biggest%20wildfire%20season%20ever. Photo: Noah Berger/AP Highway 162 Bear Fire burns in Oroville, California, Wednesday, September 9, 2020. - 15 - HUMANS HAVE MOVED CLOSER TO FORESTLANDS Expanded the Wildland–Urban Interface Tubbs Fire - burned parts of Napa, Sonoma, and Lake counties • $1.2 billion in damages • over 5,000 structures destroyed (5% of the housing stock in the city of Santa Rosa) NASA satellite image shows active fires on October 9, 2017. USGCRP, 2018: Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II: Patrick Gonzalez, UC Berkeley forest ecologist and climate change scientist, https://www.capradio.org/articles/2020/09/03/wildfires-in-california-will-continue-to-get-worse-climate-change-experts-explore-why/ The results is larger and more damaging fires 60% increase in wildfire-related property damage costs since 2008 - 16 - TOPICS COVERED The Need for Resilient Pavements Defining Resiliency Improving a Pavement’s Resiliency 9/28/2020 5 - 17 - INTRODUCTION TO RESILIENCE The ability to … anticipate, prepare for, and adapt … withstand, respond to, and recover rapidly…1 Performance Time 1) Drop in Performance 2) Recovery time (full, or partial improvement) Resilience with respect to an event (eg. Flooding, fire, earthquake, etc ) is characterized by two parameters: 1. Drop in performance, induced by the event (eg. reduced ability to carry load). 2. Recovery time to reinstate or improve performance. Green is more resilient than Red • Faster recovery time • Higher level of service Blue is a hardened 2 system as it has a higher final performance level 1. FHWA Order 5520: Transportation System Preparedness and Resilience to Climate Change and Extreme Weather Events 2. Hardening Infrastructure – Elevating, upgrading, relocating assets, flood walls, berms and levees, etc. - 18 - FUNDAMENTALS TO CREATING RESILIENT SYSTEMS Prevention, Protection & Mitigation Strategies have Benefit / Cost Ratios range from 2:1 to 9:1 Hierarchy to Resilient Systems 1 1. Prevention: stop a … manmade or natural disasters 2. Protection: secure against …manmade or natural disasters 3. Mitigation: reduce …. by lessening the impact of disasters 4. Response: … meet basic human needs after an incident 5. Recovery: …assist communities affected by an incident to recover effectively Developing a resilient pavements / roadway infrastructure requires an understanding the risk and damaged caused for each climate hazards 1. AASHTO. Fundamentals of Effective All Hazards Security and Resilience for State DOTs, 2015. 2. Mitigation Saves: Utilities and Transportation Infrastructure Investments Can Provide Significant Returns, The National Institute of Building Sciences, 2019 3. Estimating the benefits of Climate Resilient Buildings and Core Public Infrastructure (CRBCPI), Institute for Catastrophic Loss Reduction, February 2020 - 19 - INCREASED FLOODING IS IMPACTING OUR PAVEMENT STRUCTURES Need to distinguish between Inundation and Washout Impacts Washout Rapid flow of flood water / high current that scours and washes out the pavement structure Pavement type has little impact Inundation The rise of water that submerges the pavement. No rapid flow or current Pavement type does have an impact - 20 - CONCRETE AND ASPHALT PAVEMENTS ARE DIFFERENT DUE TO HOW THEY TRANSMIT LOADS TO THE SUBGRADE Concrete’s rigidity spreads the load over a large area & keeps pressures on the subgrade low • Load - more concentrated & transferred to the underlying layers • Higher deflection • Subgrade & base strength are important • Requires more layers / greater thickness to protect the subgrade Asphalt Pavements are Flexible Concrete Pavements are Rigid 7000 lbs load pressure 15 - 20 psi Asphalt Base Subbase Subgrade pressure ~3 - 7 psi Concrete Subbase Subgrade • Load – Carried by concrete and distributed over a large area • Minor deflection • Low subgrade contact pressure • Subgrade uniformity is more important than strength 9/28/2020 6 - 21 - FLOODING CAUSES THE SUBGRADE TO BECOME SUPERSATURATED Moisture infiltrates base, pushes the subgrade particles apart and weakens the system Flooding does not impact the concrete’s load carrying capacity to the same degree as asphalt’s • Lowered subgrade strength & reduced modulus • Reduced load carrying capacity • Takes ~1 year to regain strength • Loading during this times accelerates pavement damage / deterioration • Reduced pavement life • Maintains high level of strength / stiffness • Subgrade is weak, but still uniform • Spreading of the load means subgrade is not overstressed • Little impact on the serviceability / life Concrete Pavements are Rigid 7000 lbs load pressure 15 - 20 psi Asphalt Base Subbase Subgrade pressure ~3 - 7 psi Concrete Subbase Subgrade Asphalt Pavements are Flexible - 22 - SOAKING REDUCES STRENGTH OF SOILS BY 20 TO 40% Different Soils (clays, silts, sands, clay sands, etc) react differently but all decrease 0 5 10 15 20 25 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 Un-soaked vs 4-day Soaked CBR Comparisons Inorganic Clays (CL Type Soil) Clayey Sands (SC Type Soil) Percent Decrease Avg = 32.5% Range = 7.6% - 49.1% Percent Decrease Avg = 21.5% Range = 2.7% - 34.7% 4-day soaked CBR Un-soaked CBR C al if o rn ia B ea ri n g R at io ( C B R ) V al u e 0 5 10 15 20 25 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 Silty Sands (SM Type Soil)Inorganic Silts (ML Type Soil) Percent Decrease Avg = 42.1% Range = 3.9% - 65.4% Percent Decrease Avg = 30.5% Range = 0.7% - 48.9% Source: Comparison Between Soaked and Unsoaked CBR, Sathawara Jigar K & Prof. A.K.Patel; International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974 - 23 - RESEARCH FINDINGS INDICATE IT TAKES UP TO 1 YEAR FOR THE SUBGRADE STRENGTH TO RECOVER FROM FLOODING After the flood waters recede, the pavements are structurally vulnerable For this case, this strength loss is a 40 to 60% reduction load carrying capacity and about 3 years of life Sources: 1. Decision Support Criteria for Flood Inundated Roadways: A Case Study, A. Gundla, Ph.D., E. Offei, Ph.D. G. Wang, Ph.D., P.E. C.Holzschuher, P.E. and B. Choubane, Ph.D., P.E., Presented at the 2020 TRB Annual Mtg 2. Western Iowa Missouri River Flooding— Geo-Infrastructure Damage Assessment, Repair, and Mitigation Strategies; Center for Earthworks Engineering Research, Iowa State University, Report No. IHRB Project TR-638 US 441 in Alachua County, Florida between MP 7.960 to MP 9.680 - 24 - WHEN LOOKING AT PAVEMENT’S RESILIENCY, NEED TO RECOGNIZE DAMAGE FROM 2 DIFFERENT SOURCES / TIMES Impact Types / Timing • Primary / Direct Impacts – alters the pavement structural or functional capabilities • Secondary / Indirect Impacts – Impacts due to recovery activities or use • Rescue and Emergency response during the disaster • Recovery activities (clean up and rebuilding) after the disaster 1 2 To have a resilient pavement system requires that both aspects be addressed 9/28/2020 7 - 25 - RELIEF AND RESCUE EFFORTS WILL TAKE PLACE Loading occurs both during the crisis and long after Joplin, MO Tornado (2011) Debris Hauling from Camp Fire, Paradise, CA (2018) 3.66 million tons removed over a nine-month period Hurricane Florence (2018) - 26 - NEED TO ACCOUNT FOR LONG TERM SECONDARY IMPACTS WHEN DISCUSSING PAVEMENT RESILIENCE Weakened pavement & additional loading can lead to early rehabilitation needs Performance Time Design Life Early Rehab Primary impacts Secondary impacts Green is more resilient than Red • Faster recovery time • Higher level of service • Less Secondary damage Pavement Resilience should be characterized by three parameters: 1. Drop in performance, induced by the event (eg. reduced ability to carry load). 2. Recovery time to reinstate or improve performance. 3. Ability to withstand emergency and recovery activities - 27 - TOPICS COVERED The Need for Resilient Pavements Defining Resiliency Improving a Pavement’s Resiliency - 28 - APPROACHES TO IMPROVE A HIGHWAY’S / PAVEMENTS RESILIENCE Adapted from Bruneau, 2003 and McDaniels, 2008 Adaptive Resilience – Capacity to learn and make decisions to avoid future loss based on the type of disturbance 1) Modifications before disruptive events that improve system performancePerformance TimeTime to Full Recovery 2) Repairs after disruptive event to restore system functionality Lost Performance Event 9/28/2020 8 - 29 - ONE OFTEN DISCUSSED APPROACH IS ELEVATING THE ROAD ABOVE FLOODING ELEVATION Elevating the roadway is not cheap and it is not possible to raise all roadways Elevation View of SR54 Viaduct From Old SR54 Alignment, Fenwick DE Cost = $16 M in 2001 Schematic and Photo courtesy of Jim Pappas, DELDOT - 30 - ANOTHER APPROACH IS ROAD ABANDONMENT Old Corbitt Road – Odessa, Delaware Abandoning the roadway is not always possible Schematic and Photo courtesy of Jim Pappas, DELDOT • Overtops daily due to tides • 340 Avg Daily Traffic (ADT) • Traveling time will be slightly increased by approximately 2 to 3.5 minutes. • Alternate - 250’ long concrete structure. Estimated cost = $2.5M - 31 - STIFFER PAVEMENTS ARE MORE RESILIENT TO INUNDATION FLOODING Stiffer Pavements are less impacted by subgrade strength loss and recover faster (stiffer = concrete, cement stabilized bases, increased asphalt thickness) Performance Time (years) Concrete Asphalt Early Rehab Time the road is submerged / not passable 1) Lower drop in performance (Both Short and long term) 2) Quicker opening 3) Shorter recovery time Design Life 4) Less Secondary impacts (less dependence on subgrade / base strength) - 32 - KEY FINDINGS FOR PAVEMENTS THAT WERE SUBMERGED BY HURRICANE KATRINA Submerged pavements were weaker than non-submerged pavements • Asphalt pavements − Overall strength loss ≈ two inches of new asphalt concrete − Damage occurred regardless of the length of time the pavement was submerged − Cost: $50 million to rehabilitate 200 miles of submerged asphalt roads • Concrete Pavements − Little relative loss of strength due to flooded conditions − Resilient modulus(Mr) is similar for submerged and non-submerged pavements − No information given on repairs or repair costs Impact of Hurricane Katrina on Roadways in the New Orleans Area, Technical Assistance Report No. 07-2TA Kevin Gaspard, Mark Martinez, Zhongjie Zhang, and Zhong Wu; LTRC Pavement Research Group, March 2007 9/28/2020 9 - 33 - FLOODED PAVEMENTS RESEARCH IN AUSTRALIA FOUND SIMILAR RESULTS Road authorities may want consider changing their roads into flood-resilient pavements. A rigid pavement performs better than composite and flexible road groups • Composite and flexible road groups show similar performance up to 2–3 years. • Rigid pavement performs the best at any probability of flooding, and flooding effect is not critical A pavement’s strength may be enhanced by: • Strengthening with an overlay • Layer stabilization. • Converting the road into a rigid or composite pavement through granular layers’ stabilization. Estimating Pavement’s Flood Resilience; Misbah U. Khan, CPEng; Mahmoud Mesbah, Ph.D.; Luis Ferreira, Ph.D.; and David J. Williams, Ph.D.; American Society of Civil Engineer's Journal of Transportation Engineering, Part B Pavements, 2017 “It is settled that a rigid pavement is the more flood-resilient.”(p- 5) - 34 - PAVEMENTS IN HOUSTON HAVE BEEN FLOODED SEVERAL TIMES But roadways are opened as soon as water has receded Resilient Pavement Structures in Texas, Andrew Wimsatt, Ph.D., P.E., Texas A&M Transportation Institute and Lisa Lukefahr, P.E., Texas Concrete Pavement Association ESALS – Equivalent Single Axle Loads. It is how pavement engineering defines traffic Opened roadway shortly after Hurricane Harvey I-610 to I-45 11” CRCP UBOL & 14” CRCP (Const = 1995-2000) Design= 43M ESALS, Carried = 92M ESALS Southmore to Yellowstone 9” CRCP (Const = 1983 & 1984) Design = 7M ESALS, Carried = 22M ESALS Both sections have been flooded at least three times since original construction - 35 - ACTIVITIES THAT CAN BE USED TO “HARDEN THE PAVEMENT SYSTEM” Adopt & Use Concrete Pavement Photos courtesy of Erdman Anthony https://www.erdmananthony.com/Our-Projects/project/484 Yacht Harbor Manor Neighborhood Improvements, Riviera Beach, Florida - 36 - ACTIVITIES THAT CAN BE USED TO “HARDEN THE PAVEMENT SYSTEM” Modify “Design Standards” to be based on weakened subgrade condition Almost All Pavement Designs in Australia are based on soaked subgrade conditions 9/28/2020 10 - 37 - Concrete overlay increases both the height and the structural strength of the roadway 7000 lbs load. 7000 lbs load. pressure 15 - 20 psi Asphalt Base Subbase Subgrade Pressure ~3 - 7 psi at the top of the Asphalt layer Base & subgrade pressures are even lower Concrete Asphalt Base Subbase Subgrade Road Elevation raised the height of the overlay ACTIVITIES THAT CAN BE USED TO “HARDEN THE PAVEMENT SYSTEM” Use Concrete Overlays - 38 - Moisture infiltrates base • Through high water table • Capillary action • Causing softening, lower strength, and reduced modulus Cement stabilization reduces permeability • Helps keep moisture out • Maintains high level of strength and stiffness even when saturated High water table Un-stabilized Granular Base FDR w/ Cement- Stabilized Base 100 psi 15 psi 100 psi 4 psi ACTIVITIES THAT CAN BE USED TO “HARDEN THE PAVEMENT SYSTEM” FDR w/ Cement increases rigidity, reduces permeability, & reduces moisture susceptibility - 39 - CONCLUSIONS • We are beginning to recognize the need to make our infrastructure “Resilient” ‒ Need to define specific actions that agencies should consider when dealing with pavements ‒ Need to define how each specific “climate risk” will impact the system ‒ Must account for secondary impacts • In areas where pavements have a history of flooding (or in flood prone areas) ‒ Require pavement designs be based on lowered subgrade strength ‒ Use Stiffer or stiffen the existing pavement ‒ There are many solutions that are viable that are low costs, such as concrete overlays and FDR with cement that can be used as mitigation / hardening strategies 1 2 - 40 - DEFINING A PAVEMENT’S FIRE RESILIENCY Howe Ridge Fire from across Lake McDonald in Montana’s Glacier National Park (2018) USGCRP, 2018: Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II 9/28/2020 11 - 41 - FIRE DAMAGES CONCRETE & ASPHALT PAVEMENTS DIFFERENTLY While there are no studies on wildfires & pavements, there are studies from tunnel fires Concrete Pavements are Non Combustible • Concrete is a fire resistance material • Inert due to its purely mineral composition • Minimal or no emission of toxic gases. • Can get minor cracks, popouts, etc. as the water in the concrete / aggregate vaporizes Asphalt Pavements are Combustible • Approximate ignition temperatures is 300 – 450°C (based on asphalt material / type) • At lower temperatures, asphalt “melts” and has some thermal degradation (calcination and the detachment of aggregates) • Burning / melting releases considerable toxic gases (CO, SO2, NO, NO2) 1. IMPROVING FIRE SAFETY IN TUNNELS: The concrete pavement solution: CEMBUREAU / BIBM / ERMCO 2. Emanuele Toraldo (2013), Comparative laboratory investigation into pavement materials for road tunnels, Road Materials and Pavement Design 3. Rudi van Staden and Sam Fragomeni (2017) Fire damaged flexible pavement deterioration under dynamic loading: a finite element study, While most wild fires do not generate enough heat to cause the road to ignite There is still considerable damage - 42 - Kincade Fire ‐ photo source = cbsnews.com Noah Berger SOURCES OF ASPHALT PAVEMENT DAMAGE Pavement Scarring Due to Car Fire & Weakened Asphalt Binder / Structure are the Most Common Car fire Stages – Stage 1: 15 minutes Temp ~200 C Stage 2 : 45 to 60 min Temp ~900 C Stage 3 : Smoldering and Cool down Binder / emulsion at the surface burns and melts from aggregate / rock Results in Raveling, shoving, & rutting Emanuele Toraldo (2013), Comparative laboratory investigation into pavement materials for road tunnels, Road Materials and Pavement Design Rudi van Staden and Sam Fragomeni (2017) Fire damaged flexible pavement deterioration under dynamic loading: a finite element study, - 43 - CONCRETE PAVEMENT DAMAGE IS OFTEN LIMITED TO SURFACE SPALLING Intense heat causes the moisture inside the concrete to boil and fracture Tanker explosion on I-465 south to I-70 east ramp, Feb 20, 2020, Indianapolis Indiana Surface was sandblasted, railing and guardrail replaced and re-opened to traffic in ~12 hours - 44 - CONCRETE CAN BE MADE FIRE RESISTANT BY ADDING POLYPROPYLENE FIBERS (roughly 2% by wt) No Fibers Fibers Water in the concrete boils, forms steams and Violently spalls (moisture clog spalling) Polypropylene fibers melt and provide escape path for the steam, preventing spalling Videos: Courtesy of Dr Tyler Ley, Oklahoma State University, https://www.youtube.com/watch?v=xNFFcaljlzM 9/28/2020 12 - 45 - ANOTHER SOURCES OF PAVEMENT DAMAGE IS DRAINAGE PIPE FIRES Collapsed & Burnt out Culverts - undermine the roadway. Slope failure due to burnt out HDPE Pipe High-density polyethylene (HDPE) or polypropylene (PP) are plastic, and have a melting point of about 120 – 180 C - 46 - THE MAJOR SOURCE OF DAMAGE IS INCREASED / HEAVIER TRAFFIC Damage can be a lot or a little; and depends on traffic, weight, and pavement design Before After 2,256 156 142 1,822 346 817 1,310 295 268 1,298 454 1,072 ADT Trucks/day Daily ESALS Pre-fire Post-fire Pentz – 4.75 years of damage (cleanup) 8.00 years of damage (construction) Neal – 3.00 years of damage (cleanup) 5.25 years of damage (construction) 7% to 19% Trucks 23% to 35% Trucks - 47 - INCREASED / HEAVIER TRAFFIC DOES DAMAGE THE PAVEMENT Damage can be a lot or a little; and depends on traffic, weight, and pavement design Before After - 48 - Comparing Normal Verse Cleanup/Construction Traffic Pentz ADT Timing Percent Trucks Trucks/Day LEF Daily ESALs 1822 Current 19% 346.18 2.36 817 2256 Pre-Fire 7% 155.664 0.91 142 Neal ADT Timing Percent Trucks Trucks/Day LEF Daily ESALs 1298 Current 35% 454.3 2.36 1072 1310 Pre-Fire 23% 294.75 0.91 268 4.75 Extra years of damage per year of cleanup at this rate 3.00 Extra years of damage per year of cleanup at this rate 8.00 Extra years of damage per year of construction at this rate 5.25 Extra years of damage per year of construction at this rate Creating this type of structural damage makes the road more susceptible to water and environmental damage – further/rapidly exacerbating the damage! 9/28/2020 13 - 49 - The average loss of Pavement Condition Index score was conservatively calculated as a reduction of 20 basis points Camp Fire Paradise Private Road Damage Report: Quantifying Private Road Damage Costs Due to the Fire, Utility Restoration, Debris Removal, Hazard Tree Removal and Rebuild Efforts. Draft Report – Jan 2020 Don’t use until final; - 50 - LONG TERM EXPOSURE TO INTENSE HEAT DOES IMPACT PAVEMENT STRENGTH • First bar chart = Control (no thermal stress) • Next four bar charts = Specimens subjected to fire tests at 400 C • Durations ranging from 60 to 240 min • Last bar chart = specimens subjected to high- temperature oven test • 650 C for 60 min • Concrete ~ 35% to 40% Strength Reduction (due to the micro-evaporation of water) • Asphalt ~ 90% to 98% Strength Reduction (due to the bitumen burning, which occurs after only 15 min of fire exposure) Change in Cubic Compression Resistance (CCR) results due to fire exposure GM = Grouted Macadam. An open-grade bituminous mixture (voids content equal to 30%) filled with cement mortar Emanuele Toraldo (2013), Comparative laboratory investigation into pavement materials for road tunnels, Road Materials and Pavement Design - 51 - About the Presenters Jim Mack, P.E. – Director, Market Development, CEMEX Provides customer & internal support to identify and develop cement and concrete pavement application opportunities Works with State DOTS, Federal Agencies and industry Assns. to improve and develop standards related to cement and concrete pavement applications 30 years of pavement engineering experience Concrete pavement design, rehabilitation; construction; forensic evaluation, materials and specifications Pavement management, life cycle cost analysis and life cycle assessment (environmental impact). Education MBA – University of Chicago MSCE – University of Illinois at Urbana-Champaign BSCE – University of Illinois at Urbana-Champaign Registered Professional Engineer – Illinois and Texas Resiliency Webinar – Questions and Answers The questions submitted during the webinar follow with answers that our speakers have provided. So the damage to the roadway that happens after a flood event occurs when traffic is opened up to it and the subgrade is saturated? Flexible pavements withstand the damage less favorably than rigid pavements due to the higher wheel pressures? Indiana Essentially yes. The flooding supersaturates the support layers, which cause them (the support layers) to lose strength. When the Flexible pavement is loaded, it still delivers that high load to the underlying layers, but in their weakened state, it overstresses the pavement (subgrade stain and/or asphalt strain). If the pavements were not loaded in this weakened condition, there would be no damage (or little). It’s the loading in the weakened state that causes the damage. This is in contrast to concrete where the concrete is carrying the load, and the inundation does not impact that. Saludos a Jim desde Chile!! Su amiga, Gabriela Eguiluz, Chile Hola Gabriela – hay much tiempo que no hablar contigo. Esperando que toda esta bien. Mucha brazos y besos. 1930s were far worse regarding forest fires. Iowa I have no reference to the 1930 forest fires; and as such, this may be true. The sources I used were: 1. USGCRP, 2018: Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II: 2. Patrick Gonzalez, UC Berkeley forest ecologist and climate change scientist, https://www.capradio.org/articles/2020/09/03/wildfires-in-california-will-continue-to-get-worse-climate-change-experts-explore-why/ 3. https://www.insider.com/west-coast-wildfires-map-of-biggest-fires-color-coded-2020-9#:~:text=More%20than%2085%20large%20wildfires,California's%20biggest%20wildfire%20season%20ever One aspect that I am sure is different is the economic extent of the damage due to the expanded Wildland–Urban Interface and the increased population in contact with the fires. 4 day soak is not enough for some clay soils as certain clay soils can lose more than 50% of strength under saturation. Maryland Agree. Each soil will behave differently due to their make up (mineralogy, particle size, plasticity). That is why the report looked at so many different soils. Some hardly change at all, while others lost strength dramatically. For more information, see Comparison Between Soaked and Unsoaked CBR, Sathawara Jigar K & Prof. A.K.Patel; International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974 Two years back we did a study in Cincinnati to investigate the effect of flooding on pavement performance. Most pavements along the river belt was either composite or PCC. When the water receded, we noticed little damage to pavement. We did DCP tests and tested core samples. Agree with your findings. Ohio This is great information and feedback. Thank you. I would love to see a report if one is available. Isn't the development of more resilient foundation layers a key to the solution. In Houston the resilient foundation layer (Cement Treated Base) saved the concrete pavements during Harvey. TTI performed testing to verify that the base layer was not affected by the sustained flooding. Texas I agree with your statement that the more resilient (e.g. stiff) foundation layers can be part of the solution. As stated during the presentation, anything that stiffens up the pavement system should lead to a more flood resistant pavement. However, I disagree with the assessment that the CTB saved the concrete in Houston. CRCP’s are by nature, a very stiff pavement systems and the pressure delivered by loads to the underlying support is always going to be very low. The CTB’s just make them even lower. It is also important to note there are other concrete pavement structures in Houston. Most of the city and county concrete pavements are JRCP and are on an aggregate base (and there are 1000s of miles of them). These pavements also survived Harvey without damage. Similarly, the pavements evaluated in the other studies (LA, Australia) were jointed pavements on aggregate base and the same conclusion of “little or no damage” were found. In conclusion, based on what I have seen, having any concrete pavement type as the top surface layer will provides a high degree of resiliency because it spreads the loads out overt a large area. A CTB will stiffen the system and make it more resilient but is not necessarily needed under a concrete pavement. For an asphalt pavement, a CTB or FDR with cement is a great option for stiffening the system. See these studies 1. Structural Study of Cold Central Plant Recycling Sections at the National Center for Asphalt Technology (NCAT) Test Track, Brian K. Diefenderfer, Ph.D., P.E., Benjamin F. Bowers, Ph.D. (VTRC), Miguel Díaz Sánchez, David H. Timm, Ph.D., P.E., Auburn University, http://www.virginiadot.org/vtrc/main/online_reports/pdf/17-r9.pdf 2. Comparison of Full-Depth Reclamation with Portland Cement and Full-Depth Reclamation with No Stabilizer in Accelerated Loading Test, David Jones, Rongzong Wu, Stefan Louw, https://doi.org/10.3141/2524-13 Are you looking at the ultra strength materials (UHPC, compressive on the order of 30,000 psi) for their resiliency? Texas We have not looked at UHPC materials. I am sure they would perform, but I am not sure they would perform any better. Well-designed concrete pavements seem to do well as is. It may be interesting to see how a UHPC would work as an thin overlay, but it would have to be tested, and compared to standard concrete overlays on both on a performance and cost basis. Can we use this presentation to illustrate others, and make them conscious of the importance of considering the resiliency of a pavement? Florida, Wagner Vieira, vieirawagnerc@gmail.com Yes – please feel free to use as you see fit. Please acknowledge the source. [bookmark: _GoBack]How thick is a typical concrete overlay? Texas Unfortunately, Texas does not do many concrete overlays. The Texas examples were “new or original pavement construction.” Using concrete overlays as a hardening technique of existing pavements is just getting started. Earlier webinars in this program covered overlays in detail and are available to watch at https://cptechcenter.org/webinars-and-videos/#overlay | |
| NCC NC² Fall 2020 Online Meeting—September 3 | 👤 Katheryn Malusky 👤 Danny Lane 👤 Drew Waldrop 👤 Tyler Ley 👤 Brett Trautman | NC² Meeting | Fall 2020 |
| 2020-09-03 | 8/30/2020 1 About the Presenter • Katheryn Malusky is the Senior Program Manager for AASHTO’s National Transportation Product Evaluation Program (NTPEP). • Katheryn graduated with a Bachelor of Science degree in Chemistry from Mansfield University of Pennsylvania. • She began working for AASHTO in 2006 and has been involved with the NTPEP Program since 2008. • Katheryn manages and oversees the operations of the NTPEP program and also works closely with several of the NTPEP technical committees and the NTPEP Steering Committee. • Katheryn’s presentation will include an Overview of the NTPEP product evaluation programs that include concrete materials. Testing Programs for Concrete Materials/ Overview of Concrete Materials Katheryn Malusky Senior Program Manager for NTPEP AASHTO What is NTPEP? • NTPEP stands for the National Transportation Product Evaluation Program • Established within AASHTO in 1994, as a technical service program, who reports to the Council on Highways and Streets • A partnership between the AASHTO member agencies and industry participants • Combines the professional and physical resources of the AASHTO member departments in order to evaluate materials, products and devices of common interest for use in highway and bridge construction • Primary Goal- provide cost-effective evaluations for the AASHTO members (state DOTs) NTPEP’s Mission • Simplify the product evaluation process • Make it more cost-effective for both the manufacturer and state end user • Reduce duplication of efforts by State DOTs • Serve as a “One Stop Shop” for Manufacturers of engineered products 8/30/2020 2 What NTPEP is NOT • NTPEP does NOT evaluate “New Products” being introduced by industry for the first time • NTPEP does NOT pass or fail products (ultimately up to the state to develop and determine pass/fail criteria) • NTPEP does NOT replace the Quality Assurance activities of state DOTs or manufacturers • NTPEP does NOT supersede State Requirements for product approval. Any state can require additional testing of the product prior to approval. • If such additional testing is required, the state can appeal to NTPEP for inclusion into the Work Plan. NTPEP & State DOT Members • Voting member from each state to guide NTPEP’s mission • Product-specific technical committees within NTPEP include interested state DOT members and industry representatives • The NTPEP audits and evaluations reports serve as tools available free of charge to every state’s transportation agency. • AASHTO/NTPEP does NOT dictate how and what data to use or set as specifications for product approval or qualification. This is a decision and choice within each agency. NTPEP & Industry Partners • Transportation products & materials manufacturers submit their products to be “evaluated” • Evaluation results become available to registered DOT members on DataMine (data.ntpep.org) • Industry representatives invited to submit ideas, suggestions for improvement, and general feedback to each program How NTPEP Works • Products are evaluated according to nationally recognized test methods (e.g. AASHTO, ASTM) specified by the members of that Technical Committee in the Work Plan • When standards do not exist, the NTPEP Technical Committee convenes and establishes test protocols through ballot consensus process • Testing Service Fees assessed to industry cover actual costs for field and lab testing of products • Contributions from AASHTO members and apportionment of industry fees sustain NTPEP 8/30/2020 3 DataMine • http://data.ntpep.org • The “nucleus” of NTPEP • Data Repository for evaluation results • Accessible to all individuals with a valid state transportation agency email WWW.NTPEP.ORG Concrete Admixtures (CADD) CADD - Overview • Testing of Air Entraining Admixtures provides results that can be used to verify compliance with AASHTO M 154 (ASTM C260), “Standard Specification for Air-Entraining Admixtures for Concrete.” This evaluation provides: • Testing of “Concrete Admixtures” provides results that can be used to verify compliance with AASHTO M 194 (ASTM C494), “Standard Specification for Chemical Admixtures for Concrete.” 8/30/2020 4 CADD - Overview • CADD evaluations consist of: • Level 1 - Testing needed to verify compliance with AASHTO M 194 or M 154. • Level 2 – Uniformity and equivalence testing is an option for products that are not required to undergo Level 1 testing. This evaluation is also required within the 5- year time frame if the manufacturer requests a name change for the product. The chemical evaluation must indicate the product is the same product. • Dry Cast Admixtures and Corrosion inhibitors will be accepted by the technical committee for Level 2 testing only. • Products are again submitted for full Level 1 testing within 5 years of the initial Level 1 testing. • Specialty Admixtures (Type S) will be tested using the standard evaluation protocol without evaluating special properties. Concrete Curing Compounds (CCC) CCC - Overview • Provided testing can be used to verify compliance with: ASTM C309, “Standard Specification for Liquid Membrane- Forming Compounds for Curing Concrete.” This evaluation consists of laboratory testing. • Products should be submitted for retesting every 3 years. CCC - Overview The evaluation consists of laboratory testing which includes: • AASHTO T 155, “Standard Method of Test for Water Retention by Liquid Membrane-Forming Curing Compounds for Concrete.” • Minnesota DOT “Three-Day Settlement Test.” • ASTM D93, “Standard Test Method for Flash Point by Pensky- Martens Closed Cup Tester.” • Fourier Transform Infrared Spectroscopy (FTIR) Scan 8/30/2020 5 Rapid Set Concrete Patching Materials (RSCP) RSCP - Overview • The evaluation protocol has been developed to meet the specific needs of State DOTs and includes most aspects of: ASTM C928, “Standard Specification for Packaged, Dry, Rapid-Hardening Cementitious Materials for Concrete Repairs.” • Products evaluated by this program are: • Cementitious, polymer modified, and polymer repair materials. • Products evaluated are intended for: • horizontal use, • vertical/overhead use, or • both horizontal and vertical/overhead use. RSCP - Overview Products may be tested as “neat” and/or “extended.” • “Neat” - a product which has less that 5% aggregate retained on the 3/8” sieve with only water or liquid added • “Extended” - a product which has at least 5% aggregate retained on the 3/8” sieve which is included in the package or as an addition by the user along with water or liquid. RSCP - Overview The evaluation includes: • Lab testing of all product types. • Initial field trial of products intended for horizontal and both horizontal and vertical/overhead use. • No field trial for products intended for vertical/overhead use only. • Retesting – Lab testing every 5 years. 8/30/2020 6 Lab testing – Cementitious Products • Bond strength by direct tension and by slant shear • *Resistance to Freeze/Thaw * Manufacturers may choose to have products tested as per AASHTO T 161 Procedure A, Procedure B, or both. • Chloride ion penetration and content • Surface Resistivity • Compressive strength, neat and extended • Length change • Tensile strength • Time of setting by Vicat Needle and by penetration resistance. Lab testing – Polymer modified products: * Manufacturers may choose to have products tested as per AASHTO T 161 Procedure A, Procedure B, or both. • Bond strength by direct tension and by slant shear • Chloride ion penetration and content • Surface Resistivity • Compressive strength neat and extended • Length change • Thermal Compatibility • Time of setting by penetration resistance • *Resistance to freeze/thaw Lab testing – Polymer products • Bond strength by direct tension and by slant shear • Chloride ion penetration • Compressive strength • Time of setting by penetration resistance. • Gel time (pot life) • Thermal compatibility • Linear shrinkage & coefficient of thermal expansion Lab testing – Extender aggregate • AASHTO T 27, “Standard Method of Test for Sieve Analysis of Fine and Coarse Aggregates.” If the product is submitted for evaluation with extender aggregate, the aggregate is tested using the following methods: • AASHTO T 103, “Standard Method of Test for Soundness of Aggregates by Freezing and Thawing.” • AASHTO T 84 and/or T 85, “Standard Method of Test for Specific Gravity and Absorption of Fine Aggregate” and/or AASHTO T 85, “Standard Method of Test for Specific Gravity and Absorption of Coarse Aggregate.” 8/30/2020 7 The RSCP test deck is in Ohio • A test patch with typical size of 9 feet long, 3 feet wide, and 4 inches deep is prepared by Ohio DOT. • Photos are taken at the time of installation and at each evaluation. • Manufacturers provide labor and equipment needed to install patching material. • Field observations are made at the time of installation and at 12 and 24 months intervals. • Edge debonding • Percent of total area that becomes delaminated • Mid panel cracking • The field trial provides for evaluation of: Portland Cement Concrete Joint Sealant (JS) Hot Mix Asphalt Crack Sealant (CS) & • Hot-poured products are those that meet the requirements of ASTM D6690, “Standard Specification for Joint and Crack Sealants, Hot Applied for Concrete and Asphalt Pavements.” PCC Joint Sealants • PCC joint sealant types evaluated include hot-poured, cold-applied, and preformed elastomeric products. • Cold-applied products are those that meet the requirements of ASTM D5893, “Standard Specification for Cold Applied, Single Component, Chemically Curing Silicone Joint Sealant for Portland Cement Concrete Pavements.” • Types SL (Self-leveling) and NS (Non-sag) are evaluated. • Preformed elastomeric products are those that meet the requirements of ASTM D2628, “Standard Specification for Preformed Polychloroprene Elastomeric Joint Seals for Concrete Pavements.” • HMA crack sealer types evaluated include products meeting one of the following specifications: HMA Crack Sealers • ASTM D6690, “Standard Specification for Joint and Crack Sealants.” • ASTM D5078, “Standard Specification for Crack Filler, Hot-Applied, for Asphalt Concrete and Portland cement Concrete Pavements.” 8/30/2020 8 JS/CS - Overview • The evaluation includes lab testing and a field trial for both JS and CS products. • After the initial evaluation, products are retested (lab only) every 3 years. • If the product formulation has changed, then retesting will include both lab testing and a field trial. • Lab samples must be from the same lot or batch as material used in the field trial. Lab testing - Hot-Poured Sealers • Samples are prepared as per ASTM D5167, “Standard Practice for Melting of Hot-Applied Joint and Crack Sealant and Filler for Evaluation.” • Bond to Concrete • Resilience • Cone penetration • Asphalt Compatibility • Apparent Viscosity • Fingerprinting • Softening Point • Samples are evaluated in accordance with ASTM D6690. • Lab testing includes: Lab testing - Cold Applied Sealers • Samples are evaluated in accordance with ASTM D5893. • Tack Free Time • Effects of Heat Aging • Bond to Concrete • Ultimate Elongation and Tensile Stress at 150% Elongation • Effects of Accelerated Weathering • Slump Test (NS products) • Fingerprinting • Resilience • Hardness • Flow • Lab testing includes: Lab testing - Preformed Elastomeric Seals • Tensile Strength and Elongation • Type A Hardness • Oven Aging • Oil Swell • Low Temperature Stiffening • Low Temperature Recovery • High Temperature Recovery • Compression-Deflection • Samples are evaluated in accordance with ASTM D2628. • Lab testing includes: 8/30/2020 9 JS/CS – Field Trial • The intent is to alternate test deck locations so as to represent all climatic regions. • Test deck information gathered includes: • Annual average daily traffic • Monthly weather conditions • Deicing salt used per lane mile through the test deck • A pavement condition survey is performed prior to the field trial. • Roadway information such as pavement slope, joint spacing, joint width and the condition of joints is documented. • The test deck consists of at least 10 joints per sealant material. JS/CS – Field Trial • Water infiltration is measured as a percentage of joint length where water can leak past the sealant. Cohesive Failure Adhesive Failure The field evaluation consists of: • Adhesion and cohesion failures are measured as a percentage of the joint length. • A Sealant Condition Number (SCN) is determined using evaluations of water infiltration and stone retention. • Stone retention is evaluated as the amount of debris and stones that become embedded or stuck to the surface of the sealant. • Photographs of each joint are taken for each test cycle. Katheryn Malusky Senior Program Manager, NTPEP AASHTO Email: kmalusky@aashto.org Phone Number: 202-624-3695 www.ntpep.org http://data.ntpep.org www.transportation.org 9/2/2020 1 1 Danny Lane works for the Tennessee Department of Transportation as an Assistant Director for the Division of Materials and Tests. Danny manages the Research and Product Evaluation section within the Division. This section handles the (Qualified Products List) which consist of 45 lists with over 3,000 products. This section also manages all in house research and assists in Departmental and University research. Danny is a 40-year employee with the Department, he holds Chairmanships with in the AASHTO National Transportation Product Evaluation Program and serves as the Departments representative and voting member of the AASHTO Committee on Materials and Pavements (COMP). About the Presenter NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING Danny Lane Tennessee Department of Transportation Research & Product Evaluation Danny Lane Tennessee Department of Transportation Research & Product Evaluation TTCD 1988 / 1989 NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING TTCD IMPACTS DRUMS & DELINEATORS 9/2/2020 2 NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING AASHTOs’ National Transportation Product Evaluation Program (NTPEP) Application of Binder HFTO TEST DECKS NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING AASHTOs’ National Transportation Product Evaluation Program (NTPEP) Test Decks NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING AASHTOs’ National Transportation Product Evaluation Program (NTPEP) HFTO Test Decks 8 Binder Resin Systems Suppliers – Low-Mod Epoxies – Methyl methacrylate (MMA) – Polyesters 5 Different Aggregates – Calcined Bauxite HFST – Flint (Picher Oklahoma) Bridge Preservation – Basalt (Washington State Granite) Bridge Preservation – Taconite (Silica/Iron Oxide) Bridge Preservation – Feldspar Bridge Preservation NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING AASHTOs’ National Transportation Product Evaluation Program (NTPEP) HFTO Test Decks 3-year Evaluation for – Friction SKID Test – Bonding – Ware and Delamination Currently Evaluating (37), 200 ‘ Test Sections Placed in 2016 & 2017 – 10 Asphalt Pavement Decks (Single Lift) HFST – 9 Concrete Pavement Decks (Single Lift) HFST – 11 Concrete Bridge Decks (Double Lift) Bridge Preservation 9/2/2020 3 BEFORE DATAMINE NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING BEFORE DATAMINE NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING 6,338 2,021 286 4,031 9/2/2020 4 NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING QPL 1 Raised Pavement Markers / Snowplowable Raised Pavement Markers (RPM/SRPM) QPL 1 Delineators and Workzone Drums QPL 1 Pavement Marking Materials (PMM) QPL 3 Structural Steel Coatings/Concrete Coating Systems (SSC/CCS) QPL 4 Concrete Admixtures/Concrete Curing Compounds (CADD/CCC) QPL 8 Epoxy and Resin Based Adhesive Bonding Systems (ERB)* QPL 10 Sign Sheeting Materials/Roll Up Signs (SSM/RUP) QPL 13 Rapid Set Concrete Patch Materials (RSCP) QPL 14 Portland & Blended Cement (PBC) * NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING QPL 17 Erosion Control Products (ECP) QPL 21 Asphalt Release Agents (ARA) QPL 29 Flashing Arrow Panels (PCMS/FAP) QPL 30 Portable Changeable Message Signs QPL 23 & 31 High Friction and Thin Overlays (HFTO) QPL 36 Geosynthetics (GTX & REGEO) QPL 37 Detectable Warning Systems (DWS) QPL 39 Warm Mix Asphalt Technologies (WMA) QPL 42 Spray Applied Pipe Liners (SAPL) NEW 2019 NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING Special Provision Regarding Spray Applied Pipe Liners (SPAL) NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING 9/2/2020 5 NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING NTPEP Rapid Set Concrete Patch Materials (RSCP) QPL 15 Pre-Packaged Concrete Mixture QPL 43 Closure Pour Materials NTPEP Rapid Set Concrete Patch Materials (RSCP) DATA THE EXTENDED PRODUCT SHALL MEET THE FOLLOWING CRITERIA: 1) AASHTO T106/ASTM C 109 – or - AASHTO T22/ASTM C39 Compressive Strength: Age Compressive Strength 8 hours 4,000 PSI 24 hours For Information Only 3 days For Information Only 7 days For Information Only 28 days 6,000 PSI 2) ASTM C157 - Length Change of Hardened Concrete (cured in air) Age Maximum Length Change 28 days - 0.10 % 3) ASTM C882 - Bond Strength by Slant Shear (modified to test at early ages) Age Bond Strength 24 hours 1,000 PSI 7 days For Information Only NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING PCC Joint Sealants (JS) & Hot Mix Asphalt Crack Sealant (CS) * Detectable Warning Systems (DWS) * Epoxy and Resin Based Adhesive Bonding Systems (ERB) * Portland & Blended Cement (PBC) * NTPEP 2020 Implementation NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING 9/2/2020 6 NTPEP Audit Program NAP NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING 1,497 579 229 573 Corrugated Metal Pipe (CMP) Audit Programs Elastomeric Bridge Bearing Pads (EBB) Geosynthetics (GTX & REGEO) Guardrail/Guiderail (GRL) Reinforcing Steel/Welded Wire Reinforcement (REBAR/WWR) Thermoplastic Pipe (THP) NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING TDOT INVESTMENT NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING DesignDesign TDOT DIVISIONS BENEFITTING FROM NTPEP ConstructionConstruction StructuresStructures MaintenanceMaintenance Traffic OperationsTraffic Operations Materials & TestsMaterials & Tests SafetySafety EnvironmentalEnvironmental Occupational Health and SafetyOccupational Health and Safety NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING 9/2/2020 7 NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING STATE AGENCIES INDUSTRY PARTNERS INDUSTRY PARTNERS PARTNERSHIP CHAIRS & VICE CHAIRS CHAIRS & VICE CHAIRS COMMITTEES MEMBERSCOMMITTEES MEMBERS INDUSTRY PARTNERS INDUSTRY PARTNERS STATE AGENCIES STATE AGENCIES NATIONAL CONCRETE CONSORTIUM 2020 ANNUAL MEETING 9/3/2020 1 About the Presenter • Drew Waldrop is the State Concrete Engineer with the Alabama Department of Transportation. • He holds a Bachelor of Science degree in Civil Engineering from the University of Alabama and is a registered professional engineer in Alabama. • He has been employed with ALDOT Bureau of Materials & Tests for over 11 years. He has served as the Chairman of the NTPEP Portland & Blended Cements Technical Committee since it was established as a task force in 2018. OVERVIEW OF NTPEP PORTLAND & BLENDED CEMENT (PBC) TECHNICAL COMMITTEE DREW WALDROP, P.E. ALABAMA DOT CHAIRMAN BACKGROUND OF COMMITTEE • 2018: NTPEP IMPLEMENTATION COMMITTEE ESTABLISHES TASK FORCE TO DEVELOP WORK PLAN FOR CEMENT • CONDUCTED SURVEY OF DOT REQUIREMENTS • SPECS FOR CEMENT – DEVIATION FROM M 85 AND M 240? • FREQUENCY OF TESTING? • OTHER REQUIREMENTS? PROGRAM OVERVIEW • TESTING PROGRAM FOR ALL TYPES OF PORTLAND (AASHTO M 85/ ASTM C150) AND BLENDED (AASHTO M 240/ASTM C595) CEMENTS • QUARTERLY SAMPLES FROM PARTICIPATING MILLS PORTLAND CEMENTS BLENDED CEMENTS 9/3/2020 2 PROGRAM OVERVIEW • OPTIONAL TESTS AVAILABLE FOR ADDITIONAL FEES PROGRAM OVERVIEW • PRODUCER INFORMATION CLEARINGHOUSE FOR STATES • QMS SUBMITTED INITIALLY AND ANY TIME THERE IS A CHANGE • 6 MONTHS OF QC TEST DATA INITIALLY • MILL CERTS UPLOADED MONTHLY TESTING FACILITIES • 3 LABS AWARDED CONTRACTS • AMERICAN ENGINEERING TESTING, INC. – ST. PAUL, MN • SGS TEC SERVICES – LAWRENCEVILLE, GA • CTLGROUP – SKOKIE, IL • LABS ARE REQUIRED TO MAINTAIN AASHTO ACCREDITATION • ALL TESTING MUST BE COMPLETED WITHIN 2 MONTHS OF RECEIPT OF SAMPLE DATAMINE MODULE – PRODUCT LISTINGS 9/3/2020 3 DATAMINE MODULE – MILL CERTS DATAMINE MODULE – PRODUCT INFORMATION DATAMINE MODULE – PRODUCT TIMELINE PROGRAM BENEFITS • FOR DOTS: • FREES UP DOT RESOURCES FOR PROJECT-LEVEL TESTING • AS A SUPPLEMENT, PROVIDES INDEPENDENT 3RD PARTY TESTING FOR COMPARISON • FOR INDUSTRY: • ELIMINATES OR REDUCES REDUNDANT SAMPLING FOR DOT 9/3/2020 4 DREW WALDROP – CHAIR WALDROPA@DOT.STATE.AL.US BRIAN HUNTER – VICE-CHAIR BHUNTER@NCDOT.GOV COURTNEY WALLACE – TECHNICAL LIAISON CWALLACE@AASHTO.ORG 1 Tyler Ley, PE, PhD Professor at Oklahoma State University for 13 y Work experience with a contractor, DOT, and a consultant. Research focus – Constructability, Durability, and Novel Test methods YouTube Channel > 5M views and > 50K subscribers CONCRETE FREAK!!!! Why Do You Lose Air Volume When Pumping Air-Entrained Concrete??? and Why Does the Air Come Back? Justin Becker, Nick Seader, Chad Staffileno Tyler Ley, PE, PhD, 2 Acknowledgements • Oklahoma DOT • FHWA • Colorado DOT • Kansas DOT • Nebraska DOT • Iowa DOT • Minnesota DOT • Idaho DOT • North Dakota DOT • Pennsylvania DOT • Connecticut DOT • Illinois DOT • Indiana DOT • Michigan DOT • Wisconsin DOT • New Jersey DOT • RMC Foundation • American Concrete Pumping Association Acknowledgements • Vermont DOT • Jim Wild • Justin LaRoche 5 Overview Why do we add air to concrete? Why do pumps change the air content of concrete? Why does the air come back? 6 If you see Pistol Pete then that means that something is very important!!!! Why is this important? 8 9 1. Water sits 10 1. Water sits 2. Concrete becomes saturated 11 3. Concrete is damaged by freezing Why is this happening? 12 Why is this happening? • Air void system • Permeability – water to cement ratio • Saturation level - environment 13 Why is this happening? • Air void system • Permeability – water to cement ratio • Saturation level - environment 14 Why Do We Add Air to Concrete? Air-entrained bubbles are a key to the freeze-thaw resistance of concrete Air volume = freeze-thaw performance Smaller bubbles are more effective in providing freeze-thaw resistance and have less of an impact on our concrete than larger bubbles • Volume of air provided is the same for both. • Case B has a better air void distribution. A B What Do You Want in an Air-Void System? A B • Volume of air provided is the same for both. • Case B has a better air void distribution. What Do You Want in an Air-Void System? AASHTO PP84 Freeze Thaw Field Acceptance Air Volume > 4% SAM Number < 0.30 18 AASHTO PP84 Freeze Thaw Field Acceptance Air Volume > 4% SAM Number < 0.30 19 Where is this from? What air content do you use? 3.5 Months 5 mins Recommended Not Recommended What air content do you use? Small bubbles Large bubbles 3.5 Months 5 mins Recommended Not Recommended 0 10 20 30 40 50 60 70 80 90 100 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 D u ra b il it y F ac to r % SAM Number 0.40 WROS 20%FA 0.45 WROS 20%FA 0.35 WROS+PC1 0.40 WROS+PC1 0.40 WROS+PC2 0.40 WROS+PC3 0.40 WROS+PC4 0.40 WROS+PC5 0.40 WROS+WR 0.40 WROS 0.40 WROS+PC1 0.45 WROS 0.45 WROS+PC1 0.50 WROS 0.50 WROS+PC1 Cliff of Doom 98 mixtures 91% agreement Recommended Not Recommended 3.5 Months 10 mins UNC Charlotte 23 Discussion The SAM Number can better predict freeze thaw performance than the air volume. The SAM Number can be determined in fresh concrete in about 10 mins. Why are we doing this? Concrete pumps are essential tools in the industry but it is hard to predict how pumping will impact the air void system in concrete. 25 26 When you pump air entrained concrete one of three things will happen: 27 When you pump air entrained concrete one of three things will happen: 1. The air volume will go down 28 When you pump air entrained concrete one of three things will happen: 1. The air volume will go down 2. The air volume will go up 29 When you pump air entrained concrete one of three things will happen: 1. The air volume will go down 2. The air volume will go up 3. The air volume will stay the same - Ken Hover 30 When you pump air entrained concrete one of three things will happen: 1. The air volume will go down 2. The air volume will go up 3. The air volume will stay the same - Ken Hover Engineers are worried about this and so it is common to require sampling after the concrete pump. 31 32 Concrete is delivered here 33 Concrete is delivered here Concrete is sampled here 34 35 Ready Mix General Contractor 36 Ready Mix General Contractor I brought you concrete with the right air! 37 Ready Mix General Contractor I brought you concrete with the right air! It doesn’t have the right air any more!!! How do people deal with this? Increase the air volume before it goes into the pump so that it still has enough air when it comes out. One time this worked…. 38 39 Durable asphalt 40 1. Pressure 2. Vacuum 3. Impact How does pumping change air? Mechanisms 41 1. Pressure 2. Vacuum 3. Impact 1. Pressure Mechanisms How does pumping change air? Methods • Investigate the following before and after pumping: • Air volume • SAM Number (air void spacing) AASHTO TP 118 • Spacing factor (petrographic analysis) ASTM C 457 • Freeze-thaw performance ASTM C 666 42 Mixture Design • 0.45 w/cm • 20% Class C ash • 6.5 sacks (611 lbs) • Limestone and natural sand • 5” to 8” slump Air contents from 4% to 8% With and without water reducer/retarder 33 lab mixtures 44 45 Pipe Network Lab Pumping Information • 4” diameter pipe • 60’ of steel pipe • 10’ Rubber hose • pumping pressures from 55 to 110 psi 47 Failure (DF) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0% 1% 2% 3% 4% 5% 6% 7% 8% D u ra b ili ty F ac to r Air Content, % Before Pumping After Pumping Previous Work Lab data 48 Failure (DF) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0% 1% 2% 3% 4% 5% 6% 7% 8% D u ra b ili ty F ac to r Air Content, % Before Pumping After Pumping Previous Work Lab data Pumped concrete Non-pumped concrete 49 33 Fresh Air > 4.0% SAM # < 0.32 Before Pumping After Pumping Hardened Concrete Summary Summary 50 33 Fresh Air > 4.0% SAM # < 0.32 11 Fresh Air > 4.0% SAM # < 0.32 Before Pumping After Pumping Hardened Concrete Fresh Air < 4.0% SAM # > 0.32 51 33 Fresh Air > 4.0% SAM # < 0.32 11 Fresh Air > 4.0% SAM # < 0.32 33 ASTM C666 Durability Factor > 70% Before Pumping After Pumping Hardened Concrete Summary Fresh Air < 4.0% SAM # > 0.32 5255 A Clue!!! Fresh air content after pumping Hardened air content after pumping 53 Hardened air higher than fresh air Hardened air lower than fresh air 54 Variation of test method Line of agreement Discussion • Satisfactory freeze thaw performance of pumped concrete was observed even though there were low air contents and high SAM Numbers after pumping. • BUT! There is minimal change in the spacing factor measured on the hardened concrete taken before and after pumping. 55 Discussion • The hardened and fresh measurements closely matched prior to pumping. • After pumping the hardened air content was on average 1.15x higher in the fresh air content. For example – After pumping 6% fresh and about 7% in hardened concrete The fresh measurements after pumping do not represent the performance or properties of the hardened concrete. 56 57 33 Fresh Air > 4.0% SAM # < 0.32 11 Fresh Air > 4.0% SAM # < 0.32 33 ASTM C666 Durability Factor > 70% Before Pumping After Pumping Hardened Concrete ReliableReliable Unreliable Fresh Air < 4.0% SAM # > 0.32 Does this hold for other equipment and mixtures? 58 Field Pumping Information • 62 different mixtures tested • 30+ different projects • Bridge decks, walls, sidewalk, parking lot, drilled shaft • 18 Different Types of Pumps • Boom lengths ranged from 100’ to 180’ • Pipes from 4” to 6” in diameter • Used three different boom configurations 60 Flat Arch A-Frame Pump configurations 61 Flat Arch A-frame 62 24% Decrease - 35% A-Frame - 21% Arch 63 64 0.098 offset 65 29% Increase - 32% A-Frame - 44% Arch - 40% Flat 0.098 offset Discussion • Air Content • 24% of samples show a significant decrease • A-frame caused the most impact on the air volume after pumping • SAM Number • 29% of samples increased significantly • Arch configuration caused the most impact on void spacing after pumping 66 How about the hardened concrete? 67 68 69 23% Increase! 70 Arch results are similar. Flat shows little loss in air. 70% 80% 90% 100% 110% 120% 130% Before After H ar d A ir / F re sh A ir x 1 0 0 ( % ) A-Frame 70 Hardened air higher than fresh air Hardened air lower than fresh air After PumpingBefore Pumping Field data 71 Discussion • The hardened and fresh measurements closely matched prior to pumping. • After pumping the hardened air content was on average 1.15x higher than the fresh air content. For example – After pumping 6% fresh and about 7% in hardened concrete • There is no significant change in the spacing factor when comparing data before and after pumping. 72 Discussion These are the same findings from the lab but with different pump configurations, equipment, and materials!!!! The fresh measurements after pumping do not seem to represent the performance or properties of the hardened concrete. 73 What is happening? 74 Where does the air change within the pump network? 75 76 a b c d e f 77 Before Pumping A B C D E F 0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% 0 10 20 30 40 50 A ir C o n te n t, % Feet along pipeline Discussion The air is lost right after the pump and stays almost constant throughout the pipe network. Additional piston strokes (pressure cycles) did not cause additional air to be lost. The Air loss coincides with point of highest pressure. 78 Why does this happen? 79 Henry’s Law – p=kc p=partial pressure of the gas c=concentration of the dissolved gas in solution k=constant Pressure Dissolved gas How does this change the bubble size distribution? 80 2” 2” 0.75” 0.75” Air pump pressure step 0 atmospheric pressuresynthetic AEA pressure step 1 pressure step 2 pressure step 3 pressure step 4 pressure step 5 pressure step 6 pressure step 7 Atmospheric pressure pressure step 0 atmospheric pressure Discussion 1. As the pressure increases the small bubbles dissolve into the surrounding solution 2. These bubbles do not immediately come back when you decrease the pressure. 94 Why do the small bubbles dissolve??? 95 Laplace-Young Equation P1=P0+4 /d • P1=internal pressure of the air bubble • P0=pressure of fluid surrounding the bubble • • d=bubble radius Why do the bubbles dissolve? • As you increase the pressure, air will dissolve in the surrounding solution (Henry’s Law) • Because the smaller bubbles are at a higher pressure they dissolve before the larger bubbles Higher press Lower press Why do the small bubbles dissolve??? What does this mean? • The pressures during pumping causes the small bubbles to dissolve and so they are not present in the fresh concrete when it discharges from the pump. • This is why the air volume decreases and the SAM Number increases. 97 98 Remember!!!! Air and SAM over time • We pumped concrete and measured how the air volume and SAM Number change over time. 99 15 min 30 min 45 min Sampling time after pumping 100 101 102 Bubbles go away Bubbles come back? 103 104 105 Bubble spacing increases Bubble spacing decreases? What is happening??? • The pressures from pumping causes the small bubbles to temporarily dissolve • But good performance in the petrographic analysis, freeze-thaw testing, and reducing SAM Number over time suggests that the dissolved air comes back before the concrete hardens. • When the air comes back it seems to be well dispersed and provides a similar spacing factor to what went into the pump. 106 107 108 109 110 111BUBBLES What does this mean? • Air Content and SAM testing after pumping are not representative of the hardened concrete. • If this is true then concrete should not be rejected for low air or high SAM Number after pumping. • It appears that sampling the concrete prior to pumping is a good indicator to the air void system in the hardened concrete. 112 What do I think needs to happen? • Testing air at the point of discharge from a pump is dangerous and it is not representative of the properties of the hardened concrete. • We need to test concrete before pumping and not require testing at the point of placement. 113 What do I think needs to happen? • I think our air testing needs to be done with the SAM because it better correlates with freeze thaw performance. • We need to have local discussions about how we need to change specifications and construction practices. 114 Integrating Construction Practices and Weather Into Freeze Thaw Specifications [TPF-5(448)] Idaho Iowa Kansas Minnesota Missouri New York 115 North Dakota Oklahoma Pennsylvania Wisconsin FHWA American Concrete Pumping Association Integrating Construction Practices and Weather Into Freeze Thaw Specifications [TPF-5(448)] Idaho Iowa Kansas Minnesota Missouri New York 116 North Dakota Oklahoma Pennsylvania Wisconsin FHWA American Concrete Pumping Association Join Now!!! 117 118 Concrete is delivered here 119 Concrete is delivered here Concrete is sampled here 120 Ready Mix General Contractor I brought you concrete with the right air! 121 Ready Mix General Contractor I brought you concrete with the right air! YAY!!! I love you. 122 BUBBLES Conclusion • Pumping was observed to modify the air content and SAM Number in both the lab and the field testing. • Based on the hardened air void analysis, freeze thaw testing, and changing SAM Number over time, the small bubbles seem to return to the concrete with a similar air void distribution and freeze thaw performance as was in the concrete before pumping. • The SAM was an invaluable tool to give insights into the performance of air before and after a concrete pump. 123 www.youtube.com/tylerley BUBBLES Questions? www.tylerley.com Tyler.ley@okstate.edu Join TPF-5(448) 8/30/2020 1 Brett Trautman works for the Missouri Department of Transportation as the Physical Laboratory Director He has worked for MoDOT for over 30 years. The first 6 years he worked in the Materials Section of the Central District before joining the Construction and Materials Division as a Field Materials Engineer. In 2013, Brett was promoted to his current position where he oversees the testing of concrete, bituminous mixtures, aggregates, rebar, and other highway construction materials He serves as the Departments representative and voting member of the AASHTO Committee on Materials and Pavements (COMP) and is the Vice-Chair for Technical Subcommittee 3a Hydraulic Cement and Lime Brett is the current Chair of the NRRA Rigid Team Brett graduated from the University of Missouri – Columbia with a degree in Civil Engineering and is a registered professional engineer in Missouri About the Presenter BT1 National Road Research Alliance (NRRA) Project Update 2020 Fall National Concrete Consortium September 3, 2020 Brett Trautman Physical Laboratory Director Missouri DOT A pool fund focusing on solving problems that impact highway agencies - Minnesota lead state Highway agencies provide input and participate in decision making needed for future construction and research Industry and academia provide their knowledge and experience - Barriers to implementation What is the NRRA? 10 Total - California (CalTran), Illinois DOT, Illinois Tollway, Iowa DOT, Michigan DOT, Minnesota DOT, Minnesota Local Road Research Board, Missouri DOT, North Dakota DOT, and Wisconsin DOT Agency Members Slide 1 BT1 Brett Trautman, 8/19/2020 8/30/2020 2 60 Total - 17 Academia - 7 Associations - 36 Private Associate Members Executive Committee - 2 members per agency 5 Teams Structure Intelligent Construction Technologies Flexibility Geotechnical Rigid Preventive Maintenance Executive Committee 2017 Synthesis (2) • Design & Performance of Concrete Unbonded Overlays • Repair of Joints Associated Distress in Concrete Pavement 2017 Projects (4) • Fiber-Reinforced Concrete Pavement • Evaluation of Long-Term Impacts of Early Opening of Concrete Pavements • Reduced Cementitious Materials in Optimized Concrete Mixtures • Compacted Concrete for Local Streets Rigid Team Efforts 2019 Projects (5) • Solutions to Mitigate Dowel/Tie-Bar Propagated Cracking • Construction Report for Jointless FRC Roundabout in Minnesota • Incorporate Joint Faulting Model into BCOA-ME • Blending of Higher Strength Aggregates with Recycled Concrete and Marginal Aggregates to Improve Concrete Properties • Performance of Concrete Overlays over Full Depth Reclamation (FDR) Rigid Team Efforts 8/30/2020 3 Call for Innovations - Additional funding available - Evaluated several projects - Three select for funding - Pavement Specific Structural Synthetic Fibers Call for Construction - For associate members - Fund construction - MnROAD monitors - Satellite locations considered 2020 NRRA Initiatives Three constructed at MnROAD - 3.5 mi. Mainline - 3.5 mi. Bypass - 2.5 mi. Low Volume Road Live traffic - Interstate 94, EB & WB Opened in 1994 2017 Projects MnROAD Fiber-Reinforced Concrete 1) Determine contribution of fibers in reducing panel fatigue cracking 2) Determine contribution of fibers in mitigating joint faulting 3) Determine optimal panel size for thin unbonded concrete overlays 4) Determine minimum thickness of FRC for low- volume streets Objectives 8/30/2020 4 Fiber-Reinforced Concrete Four Cells (506, 606, 706, & 806) Evaluating the impact fiber dosage has on fatigue cracking & joint faulting Cell lengths: Cell No. 506 606 706 806 Length 144 ft. 138 ft. 138 ft. 138 ft. Fiber-Reinforced Concrete Full depth pavement on grade All cells: 6’ x 6’ panels Fiber content: - Cell 506: No fibers (control) - Cell 606: 20% RSR - Cell 706: 30% RSR - Cell 806: 0.75% fibers by volume Pavement Details 3" Existing Class 5 base 11" Drainable aggregate base Clay subgrade 5" Fiber Reinforced Concrete Fiber-Reinforced Concrete Cell 506 – No Fibers Cell 506 – No Fibers Cell 506 – No Fibers Cell 606 – 20% RSR Fiber-Reinforced Concrete Two Cells (705 & 805) Evaluating the impact fibers have on fatigue cracking, joint faulting, & panel size Cell Lengths: Cell No. 705 805 Length 144 ft. 124 ft. 8/30/2020 5 Fiber-Reinforced Concrete Unbonded Overlay - Non-woven geotextile fabric interlayer Cell 705 - 14’W x 12’L & 12’x12’ panels Cell 805 - 6’ Wx12’L & 8’Wx12’L panels Fiber content: 20% RSR Pavement Details Fiber-Reinforced Concrete Cell 705 Cell 805 Fiber-Reinforced Concrete Two cells (139 & 239) Evaluate using fiber-reinforced concrete pavement for city streets Cell Lengths: Cell No. 139 239 Length 270 ft. 273 ft. Fiber-Reinforced Concrete Cells 139 & 239: 6’ x 6’ panels Full depth concrete on grade Fiber content: 30% RSR Pavement Details 3" Fiber Reinforced Concrete 6" Class 5 4" common borrow (silty ‐clay Clay subgrade 4" Fiber Reinforced Concrete 6" Class 5 4" common borrow (silty ‐clay Clay subgrade 8/30/2020 6 Fiber-Reinforced Concrete Cell 139 – 3 in. Cell 239 – 4 in. Cell 139 – 3 in. Cell 139 – 3 in. Early Opening to Traffic 1) Evaluate visible and non-visible immediate damage caused by early age loading 2) Quantify the effect of early loading damage on long-term performance 3) Determine minimum strength at opening or other measurable variables associated with this parameter 4) Recommend strategies for minimizing or avoiding early loading damage detrimental to long-term performance Objectives Early Opening to Traffic Six cells (124, 224, 324, 424, 524 & 624) Early sequential traffic loadings Cell No. 124 224 324 424 524 624 Length 120 ft. 120 ft. 120 ft. 115 ft. 60 ft. 20 ft. Early Opening to Traffic Standard panel size 12’W x 15’L Full depth concrete on grade Standard concrete mix Doweled joints Pavement Details 6" PCC 6" Class 6 Sand subgrade 8/30/2020 7 Early Opening to Traffic Initial Loading - Half ton pickup truck - Snow plow truck Initial Loading Cell 624 - 2-hrs (hot day) Inside Lane Outside Lane Initial Loading Cells 124 – 424 - Half ton pickup truck - Outside Lane Initial Loading Cells 124 – 424 - Snow plow truck - Inside Lane 8/30/2020 8 Initial Loading Maturity (Deg‐Hr) Flexural (psi) 100 73 200 196 300 267 400 318 Starting Day 2, 5 passes per day for first week Cell x24 Early Loading Sequence Loads applied to lanes 1st Load on Cell 124 (forward and back) 1st Load on Cell 224, 2nd load on Cell 124 1st Load on Cell 324, 2nd load on Cell 224, 3rd load on Cell 124 1st Load on Cell 424, 2nd load on Cell 324, 3rd load on Cell 224, 4th load on Cell 124 Cells 124 – 424 Cell 524 not loaded early - Control Early Opening to Traffic Reduced Cementitious Content 1) Investigate the early-age characteristics of concrete paving mixes containing low cementitious content 2) Assess the potential for durability issues with very low cementitious content 3) Identify effect of reduced cementitious content on long term serviceability and economics of concrete pavements 4) Develop recommended specifications, mixing and placement practices for the use of low cementitious content concrete mixes Objectives Reduced Cementitious Content Two Cells (138 & 238) Cells will be exposed to deicing agents Cell Lengths: Cell No. 138 238 Length 258 ft. 260 ft. 8/30/2020 9 Reduced Cementitious Content Standard panel size 12’W x 15’L Full depth concrete on grade Doweled Joints Cell 138 - Cementitious content = 500 lb./cy Cell 238 - Cementitious content = 470 lb./cy Pavement Details 138 & 238 Cell 138 – 500 lbs. Cell 238 – 470 lbs. Reduced Cementitious Content Cell 238 – 470 lbs. Core T-1 Compacted Concrete for Local Streets 1) Evaluate the feasibility of producing and placing compact concrete pavement 2) Evaluate overall field performance 3) Determine if longer joint spacing can be utilized 4) Evaluate the effectiveness of utilizing macro fibers for load transfer Objectives Where 8/30/2020 10 Rigid Team selected CCP - Cost more than anticipated SE District added CCP to a project - Contract awarded - Asked if NRRA funds could be used for research - First NRRA satellite project NRRA Involvement Outer Road – East side of I-55 Scott County Approx. 2 miles Test Strip on Oct. 24, 2018 Full Production started on Oct. 25, 2018 - SBL placed first Project Location Constructed three test sections (SBL’s) Test Section No. 1 (495 ft.) - 15 ft. joint spacing - No fibers Test Section No. 2 (504 ft.) - 12 ft. joint spacing - No fibers Test Section No. 3 (255 ft.) - 15 ft. joint spacing - 5 lbs./C.Y. macro fibers utilized (2” length) Test Sections Pavement Structure Plans Proposed 8” CCP 6” CCP 6” Type V Base 4” Type V Base 12” Soil Stabilization 8/30/2020 11 Concrete Plant Adding ACEit Admixture High Density Paver CCP Placement 8/30/2020 12 Finishing CCP Texturing CCP Curing Sawing 8/30/2020 13 Test Sections Test Section No. 1 Test Section No. 2 Test Section No. 3 Test Section No. 3 Performance – May 2020 Test Section No. 1 Test Section No. 3 Test Section No. 1 Test Section No. 2 If interested in joining contact: Glenn Engstrom (Email: glenn.engstrom@state.mn.us) or Ben Worel (Email: ben.worel@state.mn.us) The pool fund solicitation is posted at: https://www.pooledfund.org/Details/Solicitation/1531 Interested 8/30/2020 14 Questions Email: Brett.Trautman@modot.mo.gov Office: 573-751-1036 | |
| NCC NC² Fall 2020 Online Meeting—September 2 | 👤 Ethan Bahmer 👤 Dan Wadley 👤 Kevin McMullen 👤 Jeff Roesler 👤 Maria Masten 👤 Shree Rao | NC² Meeting | Fall 2020 |
| 2020-09-02 | 8/30/2020 1 About the Presenter Ethan Bahmer is the Concrete Construction Engineer for the Michigan Department of Transportation. He’s been with the Michigan Department of Transportation for over 5 years. During this time he’s been involved with research, writing and reviewing specifications, design and construction. He also holds a Masters of Science degree in Civil Engineering from Michigan State University. Performance Engineered Mix Testing (PEM Testing) PEM Testing: V-Kelly Ball (V-Kelly): Have used in the lab Have not required its use on Projects QC Test PEM Testing: Box Test: Have used it in the lab Have not required its use on Projects Perhaps require its use for trial batches QC Test 8/30/2020 2 PEM Testing: Maturity Method: MDOT has specific requirements Special Provision Contractor’s option to use Couple of projects a year PEM Testing: Formation Factor: MDOT has not used the formation factor Mainly focused on resistivity testing PEM Testing: Surface Resistivity: Testing was performed on 2 long life (30 and 50 year) pavement projects Was being conducted on all freeze- thaw samples 40+ sets of coarse aggregate samples were tested All testing and mix ingredients were provided to Jason Weiss MDOT’s experience: Fairly high level of variability Must hold Probes perpendicular to the surface Ensure the Probes’ reservoirs are full Keep Probes away from voids and aggregate located on the surface Currently MDOT is collecting data PEM Testing: Bulk Resistivity: Currently being conducted on all freeze-thaw samples Used on multiple research projects MDOT’s experience: Simpler test than surface resistivity Consistent results Ensure the sponges remain wet Keep away from metal Currently MDOT is collecting data 8/30/2020 3 PEM Testing: Super Air Meter (SAM): MDOT owns 19 SAMs Introduced to Region personnel Shadow SP: 12CF601 Requires testing for information only: Mainline Pavement Structures Barrier One test per sublot Typically 5 tests per day for mainline paving PEM Testing: Super Air Meter (SAM): Shadow SP: 12CF601 Placed in multiple projects: Previous: I-75 Monroe I-131 Grand Rapids I-69 Flint Current: I-496 Lansing Future projects Information provided to Federal Highway and CP Tech Center PEM Testing: Super Air Meter (SAM): Michigan Concrete Association’s SAM certification Class: 2 training classes completed 3 certification classed completed 3 upcoming classes (postponed due to covid) PEM Testing: Super Air Meter (SAM): MDOT’s Experience: Introduce the SAM gauge Inspectors experience Time to run the test Do not store wet gauges in cases Do not leave the gauges in the air- conditioned cab prior to testing Always have spare batteries Have a backup gauge Use the Shotgun Follow the gauge’s directions 8/30/2020 4 PEM Testing: Super Air Meter (SAM): Future Use: QC? Mix Design Verification? Quality Assurance Daily Test? Random number Testing? PWL? Ethan Bahmer Bahmert1@Michigan.gov (517) 636-4919 Works Cited: H. Sallehi, P. Ghords, O.B. Isgor, Cement and Concrete Composites, 91: 174- 188, 2018. 8/31/2020 1 DAN L. WADLEY, P.E.KANSAS DOT – RESEARCH A LONG TIME AGO… IN A GALAXY FAR, FAR, AWAY…Dan used to spend a lot of time hanging out under bridges with the tics and poison ivy writing up bridge condition states (Routine and Fracture Critical Bridge Inspections). That turned out to be an outstanding short course in concrete (and steel) deterioration case studies. With over 6,000+ bridges on the State system, of all different ages, types, sizes… that’s a lot of time spent looking at stuff falling apart.From there the hook was set, and Dan spent the next epoch in Bridge Maintence Plans – producing plans to fix the stuff that was broke, blending the worlds of Inspection and Design. From there he transferred into a regular Bridge Design Squad to learn about new construction, because why not? And then one day the phone rang… And the rest, as they say, is history… Dan is currently the Assistant Bureau Chief of Research, stationed out of the Materials and Research Center – KDOT Central Lab in Topeka. KDOT Research has a strong research partnership with both KU and KSU through our K-Trans program, but also has an internal staff of investigative Engineers and Technicians on both the concrete and asphalt fronts, as well as advanced technology and just about anything else transportation related there is to look at. Plus we have an outstanding new Research Geologist who’s about to get her very own laser!! The Lab is a great place to work with lots of fun people and fun gadgets, but perhaps best of all… he gets to spend a lot of time mixing and testing concrete!! THAT alone should make any Engineer happy--because who doesn’t love concrete!!?! ; ) KANSAS DOTNCC- FALL 2020 SHADOW PROJECT UPDATEKA-0726-01 (PHASE 1=WB) KA-0726-01 in Gove Co. , KS KA-0726-01 = $ 38.1 M 8/31/2020 2 P H A S E 1 = ( WB ) 4 2 ’x 1 2 ” N R D J ( A E ) SA M U t i l i ze d a s P r i m a r y Te st G a m e p l a n i s t o m i n i m i z e o v e r a l l E r r o r s : M A C H I N E G A S K E T L E A K S G U T S & V A L V E S P U M P G A U G E O P E R A T O R A I R D E L I V E R Y E N E R G Y D E L I V E R Y P R E C I S I O N Q A N O T E S M U D - - G - - O P T I M I Z E D S C M ’ S A D M I X T U R E S B A T C H I N G P L A C E I N G C U R I N G “ I f y o u d i d n ’ t w r i t e i t d o w n , i t n e v e r h a p p e n e d … ” – H e W h o W i s h e s h e h a d d a t a t h e n e x t m o r n i n g . F I E L D S H E E T = R E D U C E … M a c h i n e E r r o r … M A C H I N EV A R . W A T E R R U N = A a = S H O W S L E A K S S E A T S R I M G A S K E T W A K E S U P M A C H I N E W A K E S U P O P E R A T O R ! P R O V I D E S D O C U M E N T A T I O N O F D A I L Y M A C H I N E F U N C T I O N A L I T Y ! ! ! M A C H I N EE R R O R C H E C K A a < G = O K A a > G = C H E C K S A M # = < 0 . 2 0 = O K> 0 . 2 0 = N O F L Y, C H E C K 8/31/2020 3 R E D U C E … O p e r a t o r E r r o r … I S O P E R A T O R A W A K E ? P R O V E I T D A I L Y O P E R A T O R C H E C K H U M A NV A R . W A T E R R U N = M U D R U N = F I E L D S H E E T + E . S < < O R > > F I E L D S H E E T +O S U ‘ R E L I A B I L I T Y F A C T O R ’a . k . a . “ S A M ’ s C h a n c e ” I S R E S U L T R E A S O N A B L E ? P R O V E I T Q U A N T I F Y … M a c h i n e + O p e r a t o r … O . S . U . R E L I A B I L I T Y F A C T O R Q U A N T I F Y … M u d R u n s … F O R E A C H M I X : C A L C U L A T E A G G R E G A T E C O R R E C T I O N F A C T O R = - - G - - - - R A N G E - -( F O R O U R M A C H I N E )M I N . = 0 . 2 *T Y P. = + / - 0 . 3 *M A X . = 1 . 2 * * ( P r e s u m e s t h e C a l i - c a n u s e d t o c a l i b r a t e t h e S A M . ) M U D V A R . P R E L I M I N A R Y R E S U LT S …W B M O T I O N 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 7/24/19 8/3/19 8/13/19 8/23/19 9/2/19 9/12/19 9/22/19 SAM # PROJECT TIME KSU RESEARCH OAKLEY D:3 D:6 KOSS KOSS DAILY X 8/31/2020 4 P R E L I M I N R Y R E S U LT S … M A L L E T V S . S T I N G E R 0 1 2 3 4 5 6 7 8 9 10 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 As = % B efo re P ave r Ai r by SA M M ete r SAM # KDOT KOSS OK ATTN!! POOR POOR STINGERCONSOLODATIONS MALLET STRIKECONSOLODATION A s - H A - S F V S . S A M # P R E L I M I N R Y R E S U LT S … 4 5 6 7 8 9 10 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 As % SAM # As % vs. SAM # 4 5 6 7 8 9 10 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 HA % SAM # HA % vs. SAM # 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 SPA CIN G F ACT OR (IN) SAM # SF % vs. SAM # FINE COARSE S P A C I N G F A C T O R V S . H A % - S S - S A M # 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 SPA CIN G F ACT OR (IN) SAM # SF vs. SAM # FINE COARSE 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 400 600 800 1000 1200 SPA CIN G F ACT OR (IN) SPECIFIC SURFACE (IN^-1) SF v. S_SURF 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 0 2 4 6 8 10 SPA CIN G F ACT OR (IN) HA %) SF vs. HA % P R E L I M I N R Y R E S U LT S … T A K E A W A Y S C a l c u l a t e - - G - - i f u s i n g l i m e s t o n e o r a b s o r p t i v e a g g r e g a t e s ; P e r f o r m ‘ w a t e r r u n ’ o n c e i n t h e m o r n i n g t o d o c u m e n t m a c h i n e a n d o p e r a t o r a r e f u n c t i o n i n g ; H a v e a s h e e t t o t r a c k e n d i n g p r e s s u r e s t e p s ; M a l l e t i s m o r e c o n s i s t e n t t h a n S t i n g e r ; 8/31/2020 5 T A K E A W A Y S S A M i s a d y n a m i c r e s p o n s e t e s t t h a t g i v e s y o u 4 i m p o r t a n t i n d i c a t o r s : A n i d e a o f h o w t h e m i x w i l l r e s p o n d t o e n e r g y ( h o w i t v i s u a l l y r e s p o n d s d u r i n g c o n s o l i d a t i o n ) ; T o t a l A i r ( A a - G = A s % ) ; I n d i c a t i o n o f t h e o v e r a l l q u a l i t y o f t h e a i r v o i d s y s t e m ( C o a r s e o r F i n e v i a S A M # ) , a n d c a n r e c o g n i z e c h a n g e s t o t h e m i x t h a t a r e o c c u r r i n g i n t h e f i e l d , m a k i n g i t a g r e a t - > > Q A / Q C T o o l ; U n i t W e i g h t ; A n d i t g i v e s y o u t h e s e t h i n g s q u i c k l y . F I N E R P O I N T S … < 1 . 2 5 ” S L U M P m o s t d i f f i c u l t t o r u n . M U S T d e l i v e r s u f f i c i e n t e n e r g y b y m a l l e t s t r i k e o r t e s t w i l l n o t r u n . ( R e c o m m e n d : h i t , p u s h b u t t o n t o s t a r t c o u n t d o w n , h i t 3 m o r e t i m e s . ) F i n a l C l e a n M e t i c u l o u s l y – j u s t a l i t t l e s a n d o n t h e r i m m a y e r r o r o u t t h e t e s t . D O N O T p u t t h e m a c h i n e a w a y w e t o r h a v e a n y w e t r a g s i n c a s e – i t w i l l s h i p w r e c k t h e g a u g e f o r t h e n e x t d a y . 8/31/2020 6 THANKS & BE SAFE!! 9/4/2020 1 Performance Engineered Mixtures Testing in Wisconsin Performance Engineered Mixtures Testing in Wisconsin Kevin W. McMullen, P.E. President Wisconsin Concrete Pavement Association The PEM Concept and InitiativeThe PEM Concept and Initiative • A partnership of agency and industry to – Understand what makes concrete “good” – Specify the critical properties and test for them – Design the paving mixtures to meet those specifications Performance Engineered MixturesPerformance Engineered Mixtures 9/4/2020 2 Performance Engineered Mixtures in WisconsinPerformance Engineered Mixtures in Wisconsin • More than a National priority, we have made it a state priority • FHWA Pooled Fund Study – WisDOT and WCPA are both participating and funding. • Our Joint Concrete Pavement Technical Committee is in the lead – We are getting beyond the decades old practice of blue book mixes, ACI 211 and tests of air, strength and slump. – WisDOT and contractors are supporting the emphasis on durability and performance based specifications • Wisconsin Highway Research Program project to verify what we are doing PEM Research in WisconsinPEM Research in Wisconsin • Evaluation of Current WI Mixes Using Performance Engineered Mixture Testing Protocols - Interim Report • https://wisconsindot.gov/documents2/research/0092-17- 07-interim-report.pdf Aggregate Quality and Stability OUR FIRST PRIORITY Aggregate Quality and Stability OUR FIRST PRIORITY 9/4/2020 3 Optimized Aggregate Gradation and Concrete Mixtures Optimized Aggregate Gradation and Concrete Mixtures • National Research • Tarantula Curve – Dr. Tyler Ley, OSU • Promoted by NCPTC • WisDOT and WCPA jointly developed the Standard special provisions (STSP) and specifications for WisDOT work • Used on some construction projects in 2017 and has been incorporated into all concrete pavement projects by STSP since 2018. Optimized Aggregate Gradation and Concrete Mixtures Optimized Aggregate Gradation and Concrete Mixtures • The GOALS – Stronger – More durable – Less permeable more dense concrete – Easier consolidated/workability – Improved ride The TARANTULA curve!!!! Optimized Aggregate Gradation SpecOptimized Aggregate Gradation Spec TABLE 1 TARANTULA CURVE GRADATION BAND SIEVE SIZES PERCENT RETAINED 2 in. 0 1 1/2 in. ≤5 1 in. <16 3/4 in. <20 1/2 in. 4-20 3/8 in. 4-20 No. 4 4-20 No. 8[1] <12 No. 16[1] <12 No. 30[1] [2] 4-20 No. 50 [2] 4-20 No. 100 [2] ≤10 No. 200 [2] ≤2.3 [1] Minimum of 15% retained on the sum of the #8, #16, and #30 sieves. [2] Conform to 24-34% retained of fine sand on the #30-200 sieves 9/4/2020 4 Optimized Aggregate Gradation SpecOptimized Aggregate Gradation Spec TABLE 2 JMF WORKING RANGE SIEVE SIZES WORKING RANGE[1] (PERCENT) 2 in. ±5 1 1/2 in. ±5 1 in. ±5 3/4 in. ±5 1/2 in. ±5 3/8 in. ±5 No. 4 ±5 No. 8 ±4 No. 16 ±4 No. 30 ±4 No. 50 ±3 No. 100 ±2 No. 200 ≤ 2.3 [1] Working range limits of composite gradation based on moving average of 4 tests. WisDOT Optimized Aggregate Gradation and Mixture Design STSP WisDOT Optimized Aggregate Gradation and Mixture Design STSP PART 1 • Defines optimized gradation • Outlines spec and testing requirements • Contractor eligible for 3% incentive • Sample on the belt leading to the weigh hopper • Or, working face of the stockpile • Test each component aggregate once per 1,500 CY of concrete production • Moving average of four tests What does the research project say?What does the research project say? 9/4/2020 5 WisDOT Optimized Aggregate Gradation and Mixture Design STSP WisDOT Optimized Aggregate Gradation and Mixture Design STSP PART 2 • Once aggregate gradation is optimized contractor can elect to go to mixture optimization • Can reduce cementitious content to 520 lbs/CY. • Utilizes new national design procedure • Up to 30% replacement with fly ash, slag or combination • Need to include the departments Flexural Strength for Mix Design STSP or the Concrete Pavement Flexural Strength SPV WisDOT Optimized Aggregate Gradation and Mixture Design STSP WisDOT Optimized Aggregate Gradation and Mixture Design STSP 1. Utilizes mix design procedure and spreadsheet developed by the National Concrete Pavement Technology Center 2. Utilize the spreadsheet to obtain an aggregate gradation system that fits within the Tarantula Curve and is relatively close to the power 45 curve. 3. Determine the volume of voids in the selected aggregate gradation system. a) Run ASTM C29 Specific Gravity on the proposed proportions of each aggregate. 4. Select the paste parameters; binder type, percentages, air content, w/cm. 5. Select an Initial Vpaste / Vvoids value (1.25 – 2.00). WisDOT Optimized Aggregate Gradation and Mixture Design STSP WisDOT Optimized Aggregate Gradation and Mixture Design STSP 6. Calculate the paste content utilizing the spreadsheet. WisDOT requires a minimum cement content of 520 lbs so the Vpaste / Vvoids value may need to be adjusted to meet this minimum cement content 7. Prepare trial batches and assess fresh properties and workability. 8. Prepare final trial batch and assess hardened properties. BOX TEST WorkabilityWorkability 9/4/2020 6 Assess WorkabilityAssess Workability • Box Test • V Kelly Ball BOX TESTBOX TEST BOX TESTBOX TEST From the research project 9/4/2020 7 V-KELLYV-KELLY ASR TestingASR Testing • First time incorporated into the standard specifications 501.2.5.4.4 Alkali Silica Reactivity Testing and Mitigation Requirements (1) If using coarse aggregate from sources containing significant amounts of fine-grained granitic rocks including felsic-volcanics, felsic-metavolcanics, rhyolite, diorite, gneiss, or quartzite; test coarse aggregate according to ASTM C1260 for alkali silica reactivity. Gravel aggregates are exempt from this requirement. (2) If ASTM C1260 tests indicate a 14-day expansion of 0.15 percent or greater, perform additional testing according to ASTM C1567. Test mortar bars made with coarse aggregate and the blend of cementitious materials proposed for concrete placed under the contract. The department will reject the aggregate if ASTM C1567 tests confirm mortar bar expansion of 0.15 percent or greater at 14 days. WisDOT Optimized Aggregate Gradation and Mixture Design STSP WisDOT Optimized Aggregate Gradation and Mixture Design STSP • WisDOT Spreadsheet • Originally developed at National Center for Concrete Pavement Technology • Adapted for WisDOT use • STSP requires use and submittal of this spreadsheet for approval • http://wisconsindot.gov/Pages/doing-bus/eng-consultants/cnslt- rsrces/qmp/default.aspx New Aggregate System 9/4/2020 8 New Data Charts New Paste Quality New Mix Design (Solver) STRENGTHSTRENGTH 9/4/2020 9 Flexural StrengthFlexural Strength • WisDOT basis for design is flexural strength in AASHTO pavement design procedure. • Makes sense to assure we are achieving what was designed for Special Provision Flexural StrengthSpecial Provision Flexural Strength Maximum resistance of a concrete specimen to bending. • 6-inch x 6-inch x 21-inch concrete beams • Third-point loading in accordance with AASHTO T 97. Flexural StrengthFlexural Strength • Two SPV’s – SPV for mix qualification – SPV for strength acceptance • Incentive/disincentive pay model for flexural strength is based on data from pilot projects over the last decade Flexural StrengthFlexural Strength • http://wisconsindot.gov/Pages/doing-bus/eng- consultants/cnslt-rsrces/qmp/default.aspx • Requires design of a mix using flexural strength • Replaces all 28-day compressive strengths with flexural strengths • New pay equations 9/4/2020 10 Flexural Strength ChallengesFlexural Strength Challenges • Molds • Equipment – breakers • Curing facilities to assure QC and QV are cured equally • Sensitivity of flexural beams • Risk Management (beam and mold can weigh as much as 110 pounds) Flexural Strength Moving ForwardFlexural Strength Moving Forward • Limited use • Interstate/freeway only type projects • Greater than 20,000 square yards • Coordination with central office From the research project:From the research project: FREEZE THAW RESISTANCEFREEZE THAW RESISTANCE 9/4/2020 11 SUPER AIR METER (SAM)SUPER AIR METER (SAM) SAM Moving ForwardSAM Moving Forward • Incorporated into specifications in December 2017 • Requires doing SAM during Mix Design (715.2.3.1) • Requires SAM test once per lot during concrete paving (715.3.1.1) • Shadow specification to begin building database of where WI mixes are • Does not impact acceptance • Timeline to move to acceptance in 2021? • WisDOT moving to structure specifications. Shadow testing begins in 2020 2021 SAM spec? • 2 years of shadow specification • 587 data points • 72.7% 0.2 and 0.25 and 0.3 From the research project: 9/4/2020 12 TRANSPORT PROPERTIES (the next priority) TRANSPORT PROPERTIES (the next priority) Electric ResistivityElectric Resistivity • Durability measurement • Correlates very well with Rapid Chloride Permeability. • RPC 28-day test • This can be used on any cylinder or concrete. Formation FactorFormation Factor • Resistivity – Store a cylinder in a fixed salt solution – Pull out at desired age – Read and put back – Repeat – Calculate formation factor (x10) • F = Resistivity (bulk) Resistivity (solution) From the research project:From the research project: 9/4/2020 13 After that?After that? • Resistance to deicing salt attack? – Calcium Oxychloride test – SCM use • Shrinkage (the last piece of the puzzle) – Is this impacting pavement performance? ShrinkageShrinkage • Paste content (read the batch sheet) – Easy – Fast Project Gravel 1" 5/15/2017 Mixture Proportions Targets Actual Pounds R.D. Volume Cement Type I 342 3.15 1.74 SCM 1 F Ash 86 2.65 0.52 SCM 2 Slag 0 1.00 0.00 Coarse Agg A85006 1753 2.72 10.33 Fine Agg A25518 1318 2.66 7.94 Intermediate A85007 340 2.43 2.24 Water 180 1.00 2.88 Air % 5.0 1.35 4019 27.00 Cementitious 428 428 pcy Volume of paste 24.0 % Volume of aggs 76.0 % Volume of voids 19.2 vp/vv 125 125.0 w/cm 0.42 0.42 % SCM 1 20 20 % % SCM 2 0 0 % Mass aggs 3411 3411 pcy Excess paste, % 4.8 % Shrinkage Discussion To Date With WisDOT Shrinkage Discussion To Date With WisDOT • Pavements – Low priority – Short joint spacing – Early cracking not a performance problem/concern • Structures – Higher priority – Reduction in bridge deck cracking is a high priority QUESTIONS?QUESTIONS? Kevin W. McMullen, P.E. President Wisconsin Concrete Pavement Association 4001 Nakoosa Trail, Suite 101 Madison, WI 53714 Email: kmcmullen@wisconcrete.org Phone: (608)240-1020 Mobil: (608)209-0878 Jeffery Roesler Bio Ph.D. (1998) in CEE at University of Illinois University of California BerkeleyPost doctoral researcher (1998 2000) University of Illinois Urbana Champaign (2000 present)Professor; Associate Head & Dir. of Graduate Studies and Research(2014 present) President, Society of Concrete Pavement (2016 2020) Research area interests:Passive road sensing for AV, Concrete pavement design andanalysis, Concrete fatigue/fracture, Fiber reinforced concrete,Urban Heat Island, Photocatalytic concrete, Internal Curing, Noncontact ultrasonics for concrete construction, Recycled materialsfor concrete, Roller compacted concrete, foamed cellular concrete 1 Effect of Dowels and Tie bars on Premature Cracking in JPCP Jeffery Roesler Department of Civil and Environmental Engineering University of Illinois Urbana Champaign National Concrete Consortium Fall 2020 September 2, 2020 Acknowledgements Funding: Illinois Department of Transportation thru Illinois Center forTransportation Project R27 193 4 Charles Wienrank, Illinois DOT Chair of Technical Review Panel UIUC Researchers: Roberto Montemayor, Prakhar Gupta, Dr. John DeSantis Problem Statement Premature Cracking in Urban ConcretePavements <1 year after construction (earliest observed) Between 1 5 years after construction Why is this occurring? Construction? Design? Excessive restraint? Green Street (4th to Wright) Champaign, IL Gregory Drive (Oak to 1st) Champaign, IL Gregory Drive (1st 4th St) Champaign, IL Springfield Avenue Urbana, IL Summary of Initial Observations of Distress Extent Inspection Age (Years) No. of Lanes Slab Thickness (in.) Joint Spacing (ft) Panel Width (ft) Trans. Crack (%) Green St. 7 3 9 15 11, 10, 11 37.5 Stadium Dr. 13 4 10 10 8, 8, 8, 8 0 1st Street 1 3 10 15 10.5, 9.5, 6 0 Springfield Ave 9 2 8.5 12 11, 11 11 Gregory (Oak 1st) 4 2 8.5 15 18, 14.5 4.3 Gregory (1st 4th) 1 2 4 ~8.5 15 18, 14.5 >10* S. 4th St. 1 4 8.5 14 11, 9.5 0 John St. 10 4 8.5 14 7.5, 7.5, 7.5, 7.5 0 Logan St. 8 2 (4) 8 15 and 10 4, 11, 11, 4 25 *EstimatedTransverse and Longitudinal reinforcement had consistent spacing and depth Initial sites within Champaign Urbana, IL Primary Cracking Hypothesis Axial tensile stresses caused by excessive reinforcement inlongitudinal & transverse joints that restrain thermal expansion /contraction. Tied C&G + doweled transverse joint offer high restraint versus lowfriction subbase (granular) 1.5 inch dowels@ c c Initial Hypothesis Transverse cracking due to high restraints from tie bar / dowels (?) High restraint lead to stress development due to concrete shrinkage (temp+moisture) Re assess reinforcement design standards Reducing bar diameter? Need to confirm hypothesis in other cities 13 Restraint System: higher steel reinforcement than need forbase friction or ME tie bar design Dowels Tie Bars Construction Survey Visual assessment of construction in C U in Summer 2018 (M Coreproject). IDOT Research Project Objective TASK 1 Review of Extent of Premature Cracking of Urban JPCPIs this a problem locally? TASK 2 Select Field Survey of Urban JPCP in IllinoisOccurring throughout the state? Other states? TASK 3 Development of Premature Cracking MechanismsWhat is the source of distress?Initial hypothesis: steel reinforcement overdesigned (excessive restraint)?Slab geometry, sawcutting, friction of base layer, etc.?How to resolve? Field Evaluation Multiple districts in Illinois VISUAL Lane config. Slab geometry Distress ULTRASONIC Thickness Joint detailsTie BarsDowelsSpacing 16feet 16feet MIRA Ultrasonic Testing Distress overlapping tie barlocation Field Evaluation Tool ULTRASONIC TESTING SYSTEM (MIRA) Thickness Tie Bars Dowels Spacing District 5Chatham Lane Crack Transverse Joint Bloomington, IL District 8 (East St. Louis) Mid Panel Cracks 30 ft Panels 4 5 years old Survey Summary (May 2020 Update) State of Illinois District Survey towns/areas PrematureTransverse Cracking Observations District 1 Joliet, Naperville, Shaumburg,Aurora, Des Plaines, Crystal Lake. No 9 slabs in good shape District 2 Galena No Longitudinal cracks on 14ft median lane District 3 Oswego, Yorkville, Dwight, Morris,Utica No 9 Slabs in good shape. The only crack foundedwas at an entrance of a school. District 4 Peoria, Dunlap, Morton. No 9 slabs in good shapeCracks were present only in utilities District 5 Champaign, Urbana, Rantoul,Mahomet, Bloomington, Normal. Yes Significant amount of roads showing prematurecracks District 6 Springfield Low amount of concrete roads District 7 Effingham Yes for long panels Long panels ~30ft District 8 Granite city, Madison, East St Louis,Maryville Yes for long panels(30ft) roads in good shape (Only cracks at curb)Only long panels showed premature cracks. District 9 Carbondale Pending Updated Hypothesis of Premature Cracking Dowel/Tie Bar interaction (Excessive Restraint during contraction) Dowel bars diameter spacing Tie bar spacing # 6 bar @ Non uniform restraintSlab thickness to Curb and gutter sections (plate w/ hole effect) No grease on dowels? Low base layer friction (no resistance to contraction) Rapid temperatures drop (>40 F) Non activated contraction joints (Sawcutting) Concrete mixture proportions/constituents (Not a factor) Excessive curling Slab Geometry Summary More cracking prevalent in non traditional geometries 14 ft width slabs resulting in longitudinal cracking Slab lengths > 15 ft resulting in transverse cracking East St. Louis (D8)30 ft x 12 ft (LxW)Trans. cracking Effingham (D7)13 ft x 15 ft (LxW)Long. cracking Mahomet (D5)20 ft x 8 ft (LxW)No cracking Curtis Road Champaign, IL Photos 2020 Sawcut Timing Ultrasonic Evaluation of Joint Cracks 0 0.5 1 Time (sec) 10-3 2-3 2-4 2-5 2-6 2-7 2-8 2-9 2-10 2-11 2-12 Notch FOR CONCRETE WITH NOTCH Reflected pulse received by channel 9 Diffracted pulse received by channel 9 Reflected pulse received by channel 6Initial shear pulse received by channel 6 Am plit ude (a .u.) A scan / Time domain Signals Tran, Q. and Roesler, J. detection of concrete joint activation using normalized shear wavetransmission IJPE 2020. No crack Partial crack Full crack Metal sheet toprevent thecrack fromclosing The visible end of thecrack The start ofthe crack Test setup Sawcut Timing Ultrasonic Evaluation of Joint Cracks Diffracted pulse received by channel 7 Reflected pulse received by channel 7 Directed pulse received by channel 6 Am plit ude (a. u.) Diffracted pulse received by channel 7 Reflected pulse received by channel 7 Directed pulse received by channel 6 Am plit ude (a. u.) Time(sec) Diffracted pulse received by channel 7 Reflected pulse received by channel 7 Directed pulse received by channel 6 Am plit ude (a. u.) Time(sec) NO crack PARTIAL crack FULL CRACK Tran, Q., Roesler, J., detection of concrete joint activation using normalized shear wave transmission 2020. Sawcut Timing Ultrasonic Evaluation of Joint Cracks Healey St. (Champaign, IL) Surveyed 2019 Constructed 2017 PCC = panels Dowels/tie bars included 50% panels cracked (trans. cracking) y = -1.41x + 0.84 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.2 0.4 0.6 0.8 1 NT E 2 -11 NTE 2-7 Joint 1 Joint 2 No crack Crack Sawcut Timing Ultrasonic Evaluation of Joint Cracks Some Urban Concrete Pavement cracks are related to non activated joints Normalize the energy by the 6th energy w : i : receiver No. from 7 to 12 Normalized Transmission Energy (NTE) 3D Analysis of Urban JPCP w/ C&G Friction Friction coefficient Max. Stress @ bottom of PCC mid panel (psi) 1 6.70 10 35.68 100 115.89 infinite 174.20 2 lane road (15 ft x 11 ft) w/ C&G (15 ft x 2 ft) Dowels & tie bars (Modeled as springs) Slab base friction coefficient (initially) Uniform Temperature Drop = 27 F (15C) Dowel Bar Restraint: NCHRP 637 Findings Khazanovich, Hoegh, Snyder (2009) What is pull out force for 9 in embedment & no grease? Pd = 11.6 kips What is the force required to crack @mid slab, which is the sameforce needed to restrain joints from relieving stresses (zerodeformations) Force (P) = w*12*thickness (h)*ftft=400 psi; width=11 ft; thickness=8 inchP = 11ft*12 inch/ft*8in*400 psi = 422.4 kips Padj = 4.22.4k/2.7 = 156k (over 11 dowels or Pd 14k) Dowelled joint must resist 156 kips to crack 8 in slab!P=10k/dowel*11 dowels=110 kips (6 in)P=15k/dowel*11 dowels=165 kips (9 in) ad a/d=0.1K=2.7 to 3 P Pw h=8 in JointJoint Dowel Bar Restraint: Calculations of Slab Forces Tie bar acts as a plate w/hole Tie bar assessment PANEL 1 (Cracked Panel)Tie bar spacing Varied, 0.52 m (1.7ft) to 0.67 m (2.2ft) Length of Tie bar 0.55 m (1.8 ft) Misaligned Tie Bars No Dowel Bar Spacing 0.30 m (1.0 ft)consistent Dowel Bar Length 0.45 m (18 in.) Misaligned Dowel Bar NoLogan Street (Champaign, IL) Not primary causeof cracking Contributes tocrack developmentand propagation Tie bar assessment Midwest State Practice State highway agencies predominantly use No.5 steel diameter tie bars,with several No. 4 and ~10 states use No. 6 option (ACPA 2009) Recommended Tie Bar Guidance Malella et al. 2009. Mechanistic Empirical Tie Bar Design Approachfor Concrete ACPA, Skokie, IL Design is function of: Base type (frictional characteristics) # of adjacent tied lanes and lane width M E Tie Bar Design: Overview Objectives: Ensure joint integrity Reduce excessive lateral restraint M E Design Process (from Mallela et al., 2009) 1. Obtain design inputs 2. Estimate design thermal loading 3. Compute drying shrinkage strain 4. Determine equivalent free strain 5. Determine tie bar design parameters from tables These steps areautomated with theonline tie bar designer. L w no longitudinal restraintno load transfer consideration C&G C&G M E Tie Bar Designer: Design Criteria Maximum/critical joint opening Excessive steel yielding Joint opening limited to a critical valuecomputed for each tie bar size andembedment length Online M E Tie Bar Designer Inputs: Example State: Illinois Location: Champaign Cement type: Type I Cementitious materials content: 600 lb/yd3 Coefficient of thermal expansion: 5.5 /ºF Pavement thickness: Lane configuration: Two tied lanes Subbase type/thickness: Month of construction: July Curing procedure: Curing compound Online Tie Bar Designer: Example Results Gives automatic tiebar options Gives the equivalentamount of steel per footneeded for each grade ofsteelAllows for alternatedesigns Online Tie Bar Designer: Results vary withConcrete Pavement Inputs *Identical results for thick pavements (not necessarily limited to this range) Thickness Two Tied Tied Lanes Asphalt Treated #6 @ (Gr. 60) Length* #6 @ (Gr. 60) Length* Cement Treated #6 @ (Gr. 60) Length* #6 @ (Gr. 60) Length* Unstabilized (Granular) #5 @ (Gr. 40) Length*#4 @ (Gr. 60) Length* #5 @ (Gr. 40) Length*#4 @ (Gr. 60) Length* Updated Concrete Slab Details IDOT (2018) Slab geometry joint spacing = 12 ft (h<10 inch) & 15ft (h 10 inch) Review new tie bar guidelines (2018) Construction Joint #6x30in @ 36 inch spacing Contraction Joint #6x30in @ 36 inch spacing Previously #6x30 inch @ 24 inch (construction joint) 30 inch (contraction joint) Review new dowel bar guidelines (2018) Previously 1.5 inch diameter bars for > 8 inch (2018) Recommended National Guidance ACPA Nov. 2008. Concrete Pavement Dowel Design General guidelines Specific: DowelCAD 2.0 Premature Cracking Study: Summary MIRA ultrasonic testing device helpful for field evaluation Premature cracking can develop from multiple mechanismsSlab geometryTransverse joint restraint Dowel greasing and/or misalignmentTie bars can contributeFriction of base layerNon activated contraction joints Dowel greasing is very important! Re evaluate concrete slab design detailsSlab geometry guidelinesACPA (dowel bar details)Malella et al (2009) report on tie bar details Final Report out by Dec. 2020 9/4/2020 1 About the Presenter • Maria Masten is the State Concrete Engineer for the Minnesota Department of Transportation. • Maria has worked at MnDOT for over 25 years, starting at MnROAD and in Pavement Management as a student worker, then transitioning to the Concrete Engineering Unit for the last 22 years. • She holds a Bachelor of Science degree in Civil Engineering from the University of MN and is a registered professional engineer in Minnesota. • Maria proudly served as the previous NCC Chairperson and serves on various technical committees related to performance engineered mix designs and concrete materials. MnDOT’s Experience – Using the MIT‐Scan T2/T3 during paving Maria Masten, MnDOT Concrete Engineer National Concrete Consortium – Fall 2020 Meeting September 2, 2020 Looking back in time – NCC Spring 2012 Misaligned Dowel Bars 4 9/4/2020 2 MnDOT Current Use of MIT‐Scan T2/T3 • MnDOT owns 8 MIT‐Scan T2 devices • Used for: • Locating Dowel Bars and Tie Bars in Plastic and Hardened Concrete on active concrete paving projects • Thickness Measurements in Concrete on Grade and Whitetoppings • Steel location for Coring for CPR Investigation • Bituminous Thickness (A few projects) Placing Dowel Bars • Secure dowel bar assemblies with anchors to hold the dowel bars in the correct position and alignment while preventing movement during concrete placement. • Fasten the baskets to the substrate surface so that they do not move vertically or horizontally more than 1/4 inch. Dowel Bar Baskets • Provide dowel bar assemblies manufactured in single units for the lane widths shown on the plans • Secure dowel bar assemblies with a minimum of 8 anchors (4 on each side) to hold the dowel bars in the correct position and alignment 7 QC Plan for Anchoring Baskets 9/4/2020 3 Why is a QC Plan Needed? 9 New Patching Milled Aged Asphalt Increased Risk for Misaligned Dowel Bars 10 • Concern of baskets being clipped by concrete paving equipment on 12' wide lanes Anchoring Basket Timing • Pre‐anchored • Anchoring between trucks 12 9/4/2020 4 Anchoring Dowel Baskets on Overlays 13 Concrete Placement 14 Marking the Joint Locations • Before placing the concrete, mark the location on both sides of each transverse joint as approved by the Engineer. 15 QC Plan for Anchoring Baskets • At least 7 days before the beginning of concrete paving, provide a Quality Control Plan in writing to the Engineer for acceptance that provides a method for keeping the dowel basket assemblies anchored to the grade, the existing concrete, or into the asphalt or bond breaker Layer and into the underlying concrete. 16 9/4/2020 5 QC Plan for Anchoring Baskets Include the following at a minimum: 1) Proposed type and number of fasteners 2) Proposed installation equipment 3) Dowel basket assembly anchoring plan (i.e. Anchored all basket assemblies prior to concrete placement, one lane at a time, anchor all basket assemblies during the concrete placement operation, etc.) 4) Action plan if mis‐aligned baskets are identified during concrete pavement placement 17 Using MIT‐SCAN T2/T3 During Paving Operation Guide for the MIT‐SCAN T2 Guide to using the MIT‐ SCAN T2 device for locating reinforcement bars and dowel bar baskets can be found on the MnDOT Concrete Engineering website. http://www.dot.state.mn.u s/materials/concretepavem ent.html Use the Thickness Texture MIT‐SCAN T2 Workbook for determining scanning locations. 19 Dowel Bar and Tie Bar Placement Testing in Plastic Concrete • The Contractor shall furnish a MIT‐SCAN T2 or T3 non‐ destructive testing device. • Agency and Contractor personnel shall mutually use this non‐destructive testing device during concrete pavement construction. 9/4/2020 6 Dowel Bar and Tie Bar Placement Testing in Plastic Concrete • Contractor performs testing in the Plastic concrete when using a slip form paving machine • Not required on projects < 3,500 cubic yards • Perform testing in the presence of the Engineer unless otherwise approved by the Engineer 21 Plastic Concrete MIT‐SCAN Testing Rates • The Engineer will identify the MIT‐SCAN random testing locations using the MnDOT Thickness, Texture and MIT‐ SCAN workbook in accordance with the Schedule of Materials Control. • Offset the location of the dowel bar test to the closest contraction joint. • Before the start of paving, the Engineer will provide the MIT‐SCAN report generated from the MnDOT Thickness, Texture and MIT‐SCAN workbook to the Contractor. • Unless otherwise approved by the Engineer, perform testing with the MIT‐SCAN device in the presence of the Engineer. 22 Fill out the Thickness, Texture and MIT-SCAN T2 Workbook prior to start of the project. Go to: http://www.dot.state.mn.us /materials/concretedocs/Thi ckness_Texture_MIT‐ SCAN_Workbook_8‐1‐ 19.xlsm 23 Demonstrating Fastening Method Each Day • Before the beginning of concrete pavement placement and each day before beginning paving, demonstrate the fastening method to the Engineer for approval. • The Engineer will suspend paving operations if the Contractor fails to comply with their Quality Control Plan. 24 9/4/2020 7 Dowel Bar and Tie Bar Placement Testing in Plastic Concrete • Locate the dowel bar baskets and tie bar steel using the required walk bridge that spans the entire width of pavement 25 Plastic Concrete Contractor Testing ‐ 1st Day On the first day after pavement placement, verify location by: • Scanning at least 7 doweled transverse joints every 1000 ft (both upstream and downstream side of basket) • Scanning longitudinal (L1T) joint at a rate of at least 75 linear ft out of every 1000 ft (both ends of tie bars) 26 Plastic Concrete Contractor Testing – After 1st Day After the first day, the Engineer may allow the following reduction if the placement processes is acceptable: • Scanning at least 4 doweled transverse joints every 1000 ft • Scanning longitudinal (L1T) joint at a rate of at least 25 ft out of every 1000 ft 27 Locating Tie Bars and Dowel Bar Baskets 28 Four bars shown on the display represent four sensors on the bottom of the device Note the location of the bar in relation to the sensor. 9/4/2020 8 Dowel Bar Placement and Joint Construction • Construct all joints perpendicular to the grade. • Place dowel bars parallel to the grade and parallel to the centerline of the pavement. 29 Locating Reinforcing and Dowel Bar Baskets in Plastic Concrete 30 Immediately after Paver Concrete in Plastic Form Hover the Device over the Concrete Locating Tie Bars and Dowel Bar Baskets 31 Typical Misaligned Basket Crack 32 9/4/2020 9 Misaligned Dowel Bars 33 Contractor Jig Used to Install Correctly 34 Dowel Bar and Tie Bar Placement Testing in Plastic Concrete • Agency observations do not relieve the Contractor of the requirement to properly place the concrete reinforcement and dowel bars as shown in the plans. 35 Documentation of MIT‐SCAN T2 Results 36 9/4/2020 10 Alignment Tolerances Alignment Tolerances • Dowel Bar Baskets • Verify the saw cut is centered on the dowel bars (+/‐ 3 inches) • Verify the dowels are anchored parallel to the centerline • Tie Bar Steel • Verify the appropriate number of tie bars have been placed (more than 1 missing per panel) • Verify the saw cut is centered on the tie bar (+/‐ 5 inches) 38 Out of Alignment Tolerance • Dowel Bar Baskets • Scan both upstream and downstream from the mis‐ aligned transverse doweled joints, until at least three (3) joints are in compliance. • Tie Bar Steel • Scan both upstream and downstream from the missing or mis‐aligned tie bars, until at least three (3) consecutive panels are in compliance. 39 Out of Alignment Tolerance • If at any time the Engineer determines the dowel bar anchoring or tie bar placement processes are unacceptable due to alignment/tolerance issues, the Engineer may request the Contractor amend the placement process for the operation in question to achieve satisfactory placement of the dowel bars and tie bars. • The Engineer will consider concrete pavement that fails to comply with the alignment tolerances as unacceptable Work in accordance with 1512, “Unacceptable and Unauthorized Work.” The Engineer, in conjunction with the Concrete Engineer, will evaluate the defective concrete pavement in accordance with 2301.3Q “Workmanship and Quality.” 40 9/4/2020 11 Recommendations for alignment tolerances issues There is no single recommendation for misalignment – handled on a case‐by‐case basis Determine the severity of the misalignment ◦ # of occurrences (random or single areas) Contact the Concrete Engineering Unit for recommendations which may include the following: ◦ Monetary adjustment for future maintenance ◦ Not paying for dowel bars ◦ Full Depth Repairs (No partial depth repairs!!) ◦ Sawing through dowels 41 Is it working? • No real issues for the last 2+ years with dowel bar baskets • “Everyone much more aware of the issue and inspectors and Contractors are checking the baskets throughout the day where they did not before” – Rob Golish • Design‐Build Projects • MnDOT considers dowel basket anchoring commitment as a scoring criteria • Contractors propose increased frequency of testing of plastic concrete • Increased warranty • Use of MIT‐SCAN II (dowel scanner) in hardened concrete 42 Thank you again! For additional information or specs: Maria Masten ‐Maria.masten@state.mn.us Rob Golish – Robert.golish@state.mn.us | |
| NCC NC² Fall 2020 Online Meeting—September 1 | 👤 Terry Arnold 👤 Paul Tennis 👤 Kevin Folliard 👤 Greg Halsted 👤 James Krstulovich | NC² Meeting | Fall 2020 |
| 2020-09-01 | 8/30/2020 1 About the Presenter • Terry Arnold is the Federal Lab Manager of the Chemistry Research Laboratory at the Federal Highway Administration (FHWA) Turner-Fairbank Highway Research Center (TFHRC) in McLean, VA. • The Chemistry Research Laboratory is part of the Pavement Materials Team (HRDI-10) and carries out research into both concrete and asphalt-related materials. • Terry has more than 20 years experience in working with the chemistry of pavement materials. • Originally from the United Kingdom, Terry is a Chartered Chemist and a Fellow of the Royal Society of Chemistry in the United Kingdom. Source: FHWA. Turner-Fairbank Alkali-Silica Reaction (ASR) Aggregate Susceptibility Test T-FAST National Concrete Consortium Virtual MeetingSeptember 1, 2020 TFHRC Chemistry Laboratory • Terry Arnold • Jose Munoz • Chandni Balachandran • Freweini Zerai • Anant Shastry • John Staaf Generalities • This research is a work in progress • Highly and nonreactive aggregates—Easy • Middle aggregates—Hard; they are more dependent on alkalinity • We measure Reactive Index (RI), not physical expansion • Test should expose the aggregate to what it will see in the concrete • We have a test for coarse aggregates • We think the test will work for fine aggregates • We are working on mitigation strategies • Ultimate goal is a job mix design test 8/30/2020 2 Is This Test Any Good? Objections and questions (highlighted in red): • We welcome them • We will deal with them as we proceed Nonreactive and Highly Reactive Aggregates are Easy Nonreactive Slow Reactive Highly ReactiveModerately Reactive Influence of aggregate mineralogy on the value of RI. Very Highly Reactive Source: FHWA. Ca = calcium g = grams O = oxygen Aggregate Mineralogy/CaO Content Slow Reactive Moderately Reactive Influence of alkali content on the value of RI. Middle-of-the-Road Aggregates Source: FHWA. ASR Gels Have Different Compositions and Expansion Rates A-S-H Gel In Aggregate Cracks Ca/Si = 0.23 Expansive C-S-H Gel In Paste and Air Voids Ca/Si = 0.6 Not Expansive Aggregate Mortar Source: FHWA. Si = silicon 8/30/2020 3 Issues with ASTM C1260* (AASHTO T 303**) 1N NaOH Mortar Bar • Unrealistically high alkali level • 24-hour immersion in water—leaching of calcium • Low calcium concentration in pore solution favoring formation of expansive A-S-H gel • Leaching of silicon • Problems with measuring the physical expansion Source: FHWA. *ASTM C1260. Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method). ASTM International, 2014. **AASHTO T 303. Standard Method of Test for Accelerated Detection of Potentially Deleterious Expansion of Mortar Bars Due to Alkali–Silica Reaction. AASHTO, 2000. Na = sodium American Association of State Highway and Transportation Officials (AASHTO) Issues with ASTM C1293* Concrete Prism Water • Almost 40 percent of the initial alkali leaches out of the samples during the first 3 months of the test. • Problems with leaching silica and calcium • Problems with measuring the physical expansion Source: FHWA. *ASTM C1293. Standard Test Method for Determination of Length Change of Concrete Due to Alkali-Silica Reaction. ASTM International, 2020. Effect of various “nonreactive” sands on the ASTM C1293 expansion data. Influence of “Nonreactive” Sands Grieco J. and Willsmer T. (2017). The prescription for curing concrete (Healing ASR). Innovation & Tech Transfer Exchange. Massachusetts Department of Transportation (MassDOT). http://www.umasstransportationcenter.org/Document.asp?DocID=236 Source: FHWA. T-FAST Complicated? Objection—The T-FAST Test is overly complicated • ASTM C1260: 15 Steps Test Duration: 16 Days • ASTM C1293: 14 Steps Test Duration: 365 days • AASHTO T 380*: 22 Steps Test Duration: 56–84 Days (Miniature Concrete Prism Test (MCPT)) • T-FAST: 5 Steps Test Duration: 21 Days *AASHTO T 380. Standard Method of Test for Potential Alkali Reactivity of Aggregates and Effectiveness of ASR Mitigation Measures (Miniature Concrete Prism Test, MCPT). AASHTO, 2019. 8/30/2020 4 ASTM C1778 – 20* Standard Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete Reprinted with permission from ASTM. ASTM C1778 – 20, Standard Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete, ASTM International, 2020 A copy of the complete standard may be obtained from ASTM International, www.astm.org. AAR = alkali-aggregate reaction ACR = alkali-carbonate reaction kg = kilogram lb = pound m = meter yd = yard © 2016 ASTM International. • Simplified system has all the key players for ASR (pore solution, portlandite, and reactive aggregate). • Sealed system—leaching is not possible. • Chemical test does not just measure Si dissolution or alkali consumption or pH. • Ca and aluminum (Al) contents are linked to gel formation and its composition (linked to expansion). • Conditions mimic long-term concrete pore solution. Characteristics of T-FAST What is the T-FAST Test? • 600 g aggregate obtained by ASTM D75* or C702** • Crush sufficient material to finally end up with sufficient material retained on No. 50 and No. 100 sieves. • Crusher must not contaminate the sample • Our crusher has tungsten carbide faces Source FHWA. *ASTM D75. Standard Practice for Sampling Aggregates. ASTM International, 2019. **ASTM C702. Standard Practice for Reducing Samples of Aggregate to Testing Size. ASTM International, 2018. 3.125 g Ret. #50 (297 mm) 1.875 g Ret. #100 (149 mm) Source: FHWA. Take 5 g of Crushed Aggregate Objection: 5 g is too small to be representative. We have excellent reproducibility and agreement with published field data. mm= microns 8/30/2020 5 Use a Test Polytetrafluoroethylene (PTFE) Test Tube • Cannot use glass • This is a sealed system; there is no possibility of leaching Objection on Cost: The tubes are about $50 each; they are reusable Source FHWA. Ret. #100: 1.875 g Ret. #50: 3.125 g Source: FHWA. Load the tube mL = milliliter Place the Tube in a 55 ℃ Oven for 21 Days Objection on Cost: A standard benchtop oven will hold 200–300 tubes. There is no need for environmental chambers or rooms. One technician could prepare 20–30 tubes per day. Source FHWA. Filter the Contents and Analyze the Filtrate • We Used Inductively Coupled Plasma (ICP) • We are Looking at X-Ray Fluorescence (XRF) Objection on Cost: ICP costs about $100 thousand A department of transportation (DOT) sent us a file of ASTM C1260 results DOTs were paying $1,000 per test DOTs spent $4.2 million over 10 years Source FHWA. 8/30/2020 6 Oven 55 °Cfor 21 days Vacuum Filtration ICP Analysis for Si, Ca, Al Hypothesis: If RI > 0.45, ASR expansionIf RI ≤ 0.45, no ASR expansion Leave the Tube in the Oven for 21 Days Source: FHWA. Four testing conditions (three replicas/conditions): Condition 1: 0.13 g of CaO (0.10 g Ca(OH)2/g anhydrous cement) at 55 oC Condition 2: 0.25 g of CaO (0.17 g Ca(OH)2/g anhydrous cement) at 55 oC Condition 3: 0.34 g of CaO (0.23 g Ca(OH)2/g anhydrous cement) at 55 oC Condition 4: 0.25 g of CaO (0.17 g Ca(OH)2/g anhydrous cement) at 80 oC Testing Aggregate the Mix Alkalinity is Unknown Source: FHWA.Source: FHWA. ASR Classification Criteria1. If [Si] measured in condition 4 (80 oC) ≤ 1 millimolar (mm) nonreactive. 2. If [Si] measured in condition 4 (80 oC) > 1 mm calculate RI for all the conditions and follow classification in the table. Condition 1: 0.13 g CaO at 55 oC Condition 2: 0.25 g CaOat 55 oC Condition 3: 0.34 g CaOat 55 oC Condition 4:0.25 g CaOat 80 oC Description of Aggregate Reactivity RI ≤ 0.45 for three cases RI ≤ 2 Nonreactive 0.45 < RI ≤ 2 for one case 2 < RI ≤ 100 Slow reactive 0.45 < RI ≤ 2 for at least two cases 2 < RI ≤ 100 Moderately reactive RI > 2 for at least one case 100 < RI ≤ 1000 Highly reactive RI > 2 for at least one case RI > 1000 Very highly reactive Table. Proposed Criteria for Characterizing Aggregate Reactivity. Turner-Fairbank ASR Susceptibility Test Source: FHWA. Condition 1: 0.13 g CaO at 55 oC Condition 2: 0.25 g CaOat 55 oC Condition 3: 0.34 g CaOat 55 oC Condition 4:0.25 g CaOat 80 oC Description of Aggregate Reactivity RI ≤ 0.45 for three cases RI ≤ 2 Nonreactive 0.45 < RI ≤ 2 for one case 2 < RI ≤ 100 Slow reactive 0.45 < RI ≤ 2 for at least two cases 2 < RI ≤ 100 Moderately reactive RI > 2 for at least one case 100 < RI ≤ 1000 Highly reactive RI > 2 for at least one case RI > 1000 Very highly reactive Proposed Criteria for Characterizing Aggregate Reactivity RI Aggregate Source [Si], mmCondition 4 Condition 1 Condition 2 Condition 3 Condition 4 Description of Aggregate Reactivity Quarried Limestone, IL 0.25 N/A N/A N/A N/A Nonreactive Beckmann Quarry, TX 1.01 0.40 0.44 0.44 0.35 Nonreactive Acushnet MA 22.24 0.61 0.32 0.34 8.09 Slow reactive Wrentham, MA 47.44 0.92 0.66 0.47 29.20 Moderately reactive Bardon Trimount, MA 409 3.38 1.43 0.93 229.92 Highly reactive Henniker, NH 36.05 0.35 0.27 0.40 6.79 Non/Slow reactive Middlebury, MA 203.87 1.43 1.22 1.17 103.03 Moderately/Highly reactive Examples: TFHRC ASR Susceptibility Test Source: FHWA. Source: FHWA. 8/30/2020 7 Aggregate Source Field Performance ASTM C1260 ASTM C1293 TFHRC ASR Test Rhyolite – Albuquerque, NM Highly reactive Very highly reactive Very highly reactive Highly reactive Greywacke – Moscow, PA Highly reactive Highly reactive Highly reactive Highly reactive Mixed gneiss/schist/quartzite – Attleboro, MA Reactive Very highly reactive Moderately reactive Highly reactive Siliceous Limestone – Ontario, Canada Reactive Highly reactive Highly reactive Highly reactive Greywacke/sandstone – Taunton, MA Reactive Very highly reactive Very highly reactive Highly reactive Quarried quartzite – Dell Rapids, SD Slow reactive Moderately reactive Moderately reactive Moderately reactive Quarried granite/granite gneiss –Charlottesville, VA Slow reactive Nonreactive Moderately reactive Slow reactiveQuarried metabasalt and greenstone –Shadwell, VA Slow reactive Nonreactive Moderately reactive Slow reactive Mixed gneiss/granitic – Londonderry, NH Slow reactive Moderately reactive Highly reactive Moderately reactive Siliceous gravel – Ontario, Canada Slow reactive Moderately reactive Highly reactive Moderately reactive Limestone – San Antonio, TX Nonreactive - - Nonreactive Diabase (dolerite) – Chantilly, VA Nonreactive - - Nonreactive Mixed carbonate and siliceous – Chicago, IL Nonreactive - - Nonreactive Dolomite – Chicago, IL Nonreactive - - Nonreactive Comparison of the reactivity of well-known aggregates References: Hooton 1995, Folliard et al. 2006, Rangaraju et al. 2007, Ideker et al. 2012, Latifee and Rangaraju 2014, Golmakani and Hooton 2016, Grieco and Willsmer 2017 Does T-FAST Work? - = blank Source: FHWA. Comparison of the reactivity of 2018 MassDOT aggregates Aggregate ID ASTM C1260 ASTM C1293 AASHTO T380 TFHRC ASR Test PJKA2 Nonreactive Moderately reactive Moderately reactive Slow reactive AIW Nonreactive/Moderately reactive Moderately reactive - Moderately reactive BEN2 Nonreactive - Moderately reactive Moderately reactive MO2 Highly reactive Moderately reactive Moderately reactive Highly reactive BSN Moderately reactive - Moderately reactive Moderately reactive AIS Nonreactive Nonreactive/Moderately reactive Moderately reactive Moderately reactive BID Nonreactive - Moderately reactive Nonreactive/Slow reactive CCB Moderately reactive - Nonreactive Moderately reactive PALS Moderately reactive - Moderately reactive Moderately reactive/Highly Reactive JPCM Moderately reactive - Moderately reactive Moderately reactive/Highly Reactive JSLA2 Nonreactive - Moderately reactive Moderately reactive CCWR Nonreactive - Moderately reactive Moderately reactive BSGM Moderately reactive - Moderately reactive Moderately reactive PJKL2 Nonreactive/Moderately reactive - Nonreactive Nonreactive/Slow reactive Does T-FAST Work? - = blank Source: FHWA. Comparison of the reactivity of 2019 MassDOT aggregates Aggregate ID ASTM C1260 ASTM C1293 AASHTO T 380 TFHRC ASR Test TCW - - Moderately reactive Moderately reactive/Highly Reactive CQC - - Moderately reactive Moderately reactive JSLO Moderately reactive - Moderately reactive Moderately reactive JSLA Nonreactive - Moderately reactive Moderately reactive PALS Moderately reactive - Moderately reactive Moderately reactive PJKL Nonreactive/Moderately reactive - Nonreactive Moderately reactive BEN Nonreactive - Moderately reactive Slow reactive FL - - Nonreactive Slow reactive HHW Nonreactive - Moderately reactive Nonreactive/Slow reactive TWC Moderately reactive - - Moderately reactive PJKA Nonreactive Moderately reactive Moderately reactive Nonreactive/Slow reactive Does T-FAST Work? - = blank Source: FHWA. Correlation between Exposure Block Expansion Data and TFHRC ASR Test Evaluate ASR Reactivity of Job Mix Designs Moderately ReactiveHighly Reactive Very Highly Reactive Slow Reactive Source: FHWA. 8/30/2020 8 Comparison of Agreement Between Accelerated Tests and Block Expansion Block Farm ASTM C1260 68% ASTM C1293 71% AASHTO T 380 75% T-FAST 88% T-FAST(Sand Effect) 100% Does T-FAST Work? Source: FHWA. T-FAST and Job Mix Design • Ultimate goal is a test for job mix designs • Here we know the alkalinity from the cement mill report • We have the exact mix design • We only need to run one tube • A duplicate is always good laboratory practice • One technician could prepare 20–30 mixes per day • We are working on mitigation strategies Cooperation o Expand the calibration of the test; looking for coarse (600 g) and fine (200 g) aggregate samples with: • Previous accelerated ASR expansion data (ASTM C1260, ASTM C1293, and AASHTO T 308). • Block farm expansion data. • Field cases. o MassDOT, Pennsylvania DOT, California DOT (Caltrans), and the Federal Aviation Administration (FAA) are already cooperating. o Georgia DOT and Florida DOT expressed interest. Cooperation o For outside groups interested in running T-FAST: o We provide: • Detailed protocol. • Five aggregates with well-known reactivities. o Analytical equipment used: • Inductively Coupled Plasma (ICP) emission spectrometer. • X-ray fluorescence (XRF) spectrometer. • Atomic absorption (AA) spectrometer. o North Carolina DOT (XRF) and Caltrans (ICP). 8/30/2020 9 Thanks for your attention! Questions? 8/30/2020 1 About the Presenter • Paul Tennis is the Director of Product Standards and Technology for the Portland Cement Association (PCA). • Paul has been with PCA in various capacities for 24 years, focused on cement and concrete standards development, including ASTM and AASHTO cement specifications and concrete durability-related standards. • He holds a Bachelor of Science degree in Ceramic Engineering from Clemson University, and an MS and PhD in Materials Scienceand Civil Engineering both from Northwestern University. • He is a fellow of ACI, an ASTM Bryant Mather award recipient, pastchairman of ASTM Committee C01, and ‘friend’ of several AASHTO and TRB committees. • Fun fact: Paul attended the inaugural meeting of the Midwest Concrete Consortium in 1997 and has participated periodically in the MC2 and NC2 meetings ever since. Managing ASR in the Future 2 What is ASR? 3 Aggregates react with soluble alkalies in pore solution with silica in aggregate Alkali-Silica gel forms. AS Gel fills pores Reaction continues A little more on ASR… Courtesy of N Popoff VCNA 8/30/2020 2 What are alkalies? 5 Wikipedia What is Equivalent Alkali? • Definition Na2Oeq = % Na2O + 0.658 % K2O 0.658 is the molecular weight ratio Provides a convenient single value 6 Oxide OPC SiO2 20.55 Al2O3 5.07 Fe2O3 3.10 CaO 64.51 MgO 1.53 Na2Oeq 0.63 SO3 2.53 LOI 1.58 What is “Equivalent Alkali”? + IR and trace elements alkalies (sodium & potassium) represent a small proportion of the cement K2O + H2O 2K+ + 2OH-Na2O + H2O 2Na+ + 2OH- Most of the alkalies end up in the pore solution and the associated OH concentration is sufficient to produce a pH around 13 7 Impacts of Alkalies • Increase pH of pore solution • Improves steel reinforcement protection • Stabilizes C-S-H • Activates pozzolans and slag cement • Can improve AEA effectiveness • Can contribute to ASR with susceptible aggregates 8 8/30/2020 3 Results of Stanton’s Mortar Bar Tests (Stanton, 1940 & 1952) Expansion unlikely if cement alkalies < 0.60% Na2Oeq 0 0.1 0.2 0.3 0.4 0.5 0.2 0.6 1.0 1.4 Cement Alkalies (% Na2Oeq) Ex pan sio n a t 2 Yea rs ( %) WRONG! 9 Concrete alkali loading lb/yd3 = Portland cement alkalies % Na2Oeq Portland cement content lb/yd3 1 100× × Example: If a concrete contains 564 lb/yd3 of portland cement and the cement has an alkali content of 0.78% Na2Oeq then the alkali loading of the concrete is: 564 x 0.78 100= = 4.40 lb/yd3 Cement Alkali Content vs. Concrete Alkali Loading ( = 2.61 kg/m3) 10 Concrete alkali loading lb/yd3 Na2Oeq = Cement alkalies% Na2Oeq Cement content lb/yd3 1 100x x Cement Alkali Content vs. Concrete Alkali Loading 11 Na2Oeq% Cement Content lb/yd3 Alkali Loading lb/yd3 0.50 500 2.5 0.50 700 3.5 0.70 500 3.5 0.70 700 4.9 Effect of Concrete Alkali Loading Data courtesy of M. Thomas 0.0 2.0 4.0 6.0 8.0 10.0 0.00 0.10 0.20 0.30 0.40 0.50 0.0 1.0 2.0 3.0 4.0 5.0 6.0 Alkali loading, lb/yd3 Ex pa ns ion at 2 y ear s, % Alkali loading of concrete, kg/m3 CSA Limit 12 8/30/2020 4 What changed in the Specs? • C150/M 85 no longer include the optional low-alkali limit of 0.60% • Manufacturers are required to report Na2Oeq on all portland cement mill test reports • Note references ASTM C1778/AASHTO R 80 for guidance on ASR • Reference to the historical optional limit is included in a non-mandatory note 13 Why the Spec Change? • A 0.60% limit on cement is not protective in all cases • False sense of security • Aggregate reactivity • Concrete mix design • Alkali loading of concrete is more relevant/effective • Reporting equivalent alkalies allows alkali loading to be readily calculated • SCMs are most common solution • C1778 and R 80 provide state-of-the-art guidance 14 Approach • Classify aggregate reactivity • Level of risk (size andexposure conditions) • Criticality of structure • Level of prevention needed 15 AASHTO R 80 (PP 65)/ASTM C1778: Data Needed 16 • Prescriptive approach − Portland cement: Na2Oeq − Slag cement: Na2Oeq < 1.0%− Fly ash: CaO ≤ 18% and Na2Oeq ≤ 4.5%− Silica fume: SiO2 > 85% and Na2Oeq < 1.0% • Performance approach − Portland cement: Na2Oeq 8/30/2020 5 Figure 3 17 Figure 3 18 Table 1. Classification of Aggregate 19 Aggregate- Reactivity Class Description of Aggregate Reactivity 1-Year Expansion in CPT, % 14-Day Expansion in AMBT, % R0 Nonreactive ≤0.04 ≤0.10 R1 Moderately reactive >0.04, ≤0.12 >0.10, ≤0.30 R2 Highly reactive >0.12, ≤0.24 >0.30, ≤0.45 R3 Very highly reactive >0.24 >0.45 Table 2. Level of ASR Risk 20 Aggregate-Reactivity Class Size and Exposure Conditions R0 R1 R2 R3 Nonmassive concretea in a dry environment Level 1 Level 1 Level 2 Level 3 Massive elementsa in a dry environment Level 1 Level 2 Level 3 Level 4 All concrete exposed to humid air, buried or immersed Level 1 Level 3 Level 4 Level 5 All concrete exposed to alkalies in servicec Level 1 Level 4 Level 5 Level 6 a A massive element has a least dimension >0.9 m (3 ft). b A dry environment corresponds to an average ambient relative humidity lower than 60 percent, normally found only in buildings. c Examples of structures exposed to alkalies (sodium and potassium) in service include marine structures exposed to seawater and highway structures exposed to deicing salts (e.g., NaCl) or anti-icing salts (e.g., potassium acetate, potassium formate, sodium acetate, sodium formate, etc.). 8/30/2020 6 Table 4. Structure Classification based on Severity of Consequences of ASR 21 Class Consequences of ASR Acceptability of ASR Examplesb S1 Safety, economic, or environmental consequences small or negligible Some deterioration from ASR may be tolerated. Non–load-bearing elements inside buildings Temporary structures (e.g., <5 years) S2 Some safety, economic, or environmental consequences if major deterioration Moderate risk of ASR is acceptable. Sidewalks, curbs, and gutters Service life <40 years S3 Significant safety, economic, or environmental consequences if minor damage Minor risk of ASR acceptable. Pavements Culverts Highway barriers Rural, low-volume bridges Large numbers of precast elements where economic costs of replacement are severe Service life normally 40 to 75 years S4 Serious safety, economic, or environmental consequences if minor damage ASR cannot be tolerated. Major bridges Tunnels Critical elements that are very difficult to inspect or repair Service life normally >75 years Table 3. Level of Prevention 22 Level of ASR Risk (Table 2) Classification of Structure (Table 4) S1 S2 S3 S4 Risk level 1 V V V V Risk level 2 V V W X Risk level 3 V W X Y Risk level 4 W X Y Z Risk level 5 X Y Z ZZ Risk level 6 Y Z ZZ a a It is not permitted to construct a Class S4 structure (see Table 4) when the risk of ASR is Level 6. Measures must be taken to reduce the level of risk in these circumstances. The levels of prevention V, W, X, Y, Z, and ZZ are used in Tables 5 to 8. Table 5. Maximum Alkali Contents in Portland Cement Concrete 23 Prevention Level Maximum Alkali Loading of Concrete (Na2Oeq) kg/m3 lb/yd3 V No limit No limit W 3.0 5.0 X 2.4 4.0 Y 1.8 3.0 Za Table 8 Table 8 ZZa Table 8 Table 8 a SCMs must be used in prevention levels Z and ZZ. Table 6. Minimum SCM Levels 24 Type of SCMa Alkali Level of SCM, (% Na2Oeq) Minimum Replacement Levelb (% by Mass of Cementitious Material) Level W Level X Level Y Level Z Level ZZ Fly ash (CaO ≤18%) ≤3.0 15 20 25 35 Table 8 >3.0, ≤4.5 20 25 30 40 Slag ≤1.0 25 35 50 65 Silica fumec (SiO2 ≥85%) ≤1.0 2.0 × KGA or 1.2 × LBA 2.5 × KGA or 1.5 × LBA 3.0 × KGA or 1.8 × LBA 4.0 × KGA or 2.4 × LBA 8/30/2020 7 Table 7. Adjustment for Alkali Level of Portland Cement 25 Cement alkalies (% Na2Oeq) Level of SCM ≤0.70 Reduce the minimum amount of SCM given in Table 6 by one prevention level.a >0.70, ≤1.00 Use the minimum levels of SCM given in Table 6. >1.00, ≤1.25 Increase the minimum amount of SCM given in Table 6 by one prevention level. >1.25 No guidance is given. a The replacement levels should not be below those given in Table 6 for prevention level W, regardless of the alkali content of the portland cement. Table 8. Using SCM and Limiting Alkali Content to Provide Exceptional Levels of Prevention 26 Prevention Level SCM as Sole Prevention Limiting Concrete Alkali Loading Plus SCM Minimum SCM Level Maximum Alkali Loading, kg/m3 (lb/yd3) Minimum SCM Level Z SCM level shown for Level Z in Table 6 1.8 (3.0) SCM level shown for Level Y in Table 6 ZZ Not permitted 1.8 (3.0) SCM level shown for Level Z in Table 6 Prescriptive Approach 27 • Options for mitigation − Limit concrete alkali loading − Use of SCMs − Both Performance Approach •Uses testing to assure performance • ASTM C1567 or C1293 • <0.10% or <0.04% 28 8/30/2020 8 Performance approach: Data Needed • C1293: Adjusts mix water alkali content based on portland cement • Equivalent alkali content of portland cement or portland cement portion of blended cement 29 Conclusion • Alkali-Silica Reactivity (ASR) • Alkalies in Cement and Concrete • Cement equivalent alkali content• Concrete alkali loading• Benefits of alkalies in concrete • ASTM C1778/AASHTO R 80 for best guidancenow and for the future • http://mdot.mse.mtu.edu/dotspecs/ 30 9/9/2020 1 Bio – Kevin J. Folliard, Ph.D. Dr. Kevin J. Folliard is the Warren S. Bellows Centennial Professor of Civil Engineering in the Department of Civil, Archictectural, and Environmental Engineer at the University of Texas at Austin, where he has been on the faculty since 1999. Prior to this, Dr. Folliard was an Assistant Professor at the University of Delaware from 1997-1999 and a Senior Research Engineer at W.R. Grace & Co. from 1995-1997. Dr. Folliard received his Ph.D. in Civil Engineering from the University of California at Berkeley in 1995. His main research interest is in the area of the durability of portland cement concrete and he teaches course related to civil engineering materials, concrete technology, and concrete durability. Dr. Folliard is a Fellow of the American Concrete Institute (ACI), and he received the ACI Young Member Award for Professional Achievement in 2003 and the ACI Wason Medal for Materials Research in 2010 and 2015. In 2013, Dr. Folliard was honored with the highest teaching award given by the University of Texas System, the Regents’ Outstanding Teaching Award. Dr. Folliard has been the Principal Investigator on over $20 million in research projects while on the faculty at the University of Texas at Austin, primarily in the area of concrete durability (especially alkali-silica reaction). Dr. Folliard has authored or co-authored over 150 technical publications in his career, including more than 80 refereed journal papers. MANAGEMENT AND TREATMENT OF FIELD STRUCTURES AFFECTED BY ASR Kevin J. Folliard1, Michael D.A. Thomas2, Benoit Fournier3, and Thano Drimalas1 1The University of Texas at Austin, Austin, TX, USA 2University of New Brunswick, Canada 3Laval University, Quebec City, Quebec, Canada Fall 2020 National Concrete Consortium Webinars Sept 1 – 3, 2020 Outline of Presentation • Treatment Options for ASR-Affected Structures • FHWA Field Trials • Lessons Learned… What is Alkali-Silica Reaction, ASR? Reactive silica in aggregate Alkalis in cement paste SiO2 Na+ K+OH- OH- Na+ K+ OH- OH- Reaction between the alkalis (Na, K & OH) from the cement react and unstable silica, SiO2, in some types of aggregate Alkali- silica gel The reaction produces an alkali- silica gel The gel absorbs water from the surrounding paste … Na,K-Si … and expands. The internal expansion eventually leads to cracking of the surrounding concrete. 1 2 3 4 9/9/2020 2 Reactive Silica Sufficient Alkali Sufficient Moisture Requirements for ASR FHWA ASR Development and Deployment Program (2008 – 2013) American Association of State Highway and Transportation Officials (AASHTO). 2012. “Standard Practice for Determining the Reactivity of Concrete Aggregates and Selecting Appropriate Measures for Preventing Deleterious Expansion in New Concrete Construction.” AASHTO PP 65-11, AASHTO, 24 p. Fournier, B., Berube, M.A., Folliard, K.J. and Thomas, M.D.A. 2009. “Report on the Diagnosis, Prognosis, and Mitigation of Alkali-Silica Reaction (ASR) in Transportation Structures.” FHWA-HIF-09-004, Federal Highway Administration. Folliard, K.J., Fournier, B. and Thomas, M.D.A. 2012. “Alkali-Silica Reactivity Surveying and Tracking Guidelines.” FHWA-HIF- 12-046, Federal Highway Administration. Thomas, M.D.A., Fournier, B., Folliard, K.J., Ideker, J.H. and Resendez, B. 2006. “The Use of Lithium To Prevent or Mitigate Alkali-Silica Reaction in Concrete Pavements and Structures.” FHWA-HRT-06-133, Federal Highway Administration. Thomas, M.D.A., Fournier, B. and Folliard, K.J. 2009. “Report on Determining the Reactivity of Concrete Aggregates and Selecting Appropriate Measures for Preventing Deleterious Expansion in New Concrete Construction.” FHWA-HIF-09-001, Federal Highway Administration. Thomas, M.D.A., Folliard, K.J., Fournier, B. and Ahlstrom, G. 2012a. “AASHTO Standard Practice for Prevention of AAR.” Proceedings of the 14th International Conference on Alkali-Aggregate Reactions, Austin, Texas. Thomas, M.D.A., Fournier, B., Folliard, K.J. and Resendez, Y.A. 2012b. “Alkali-Silica Reactivity Field Identification Handbook.” FHWA-HIF-12-022, Federal Highway Administration. Thomas, M.D.A., Fournier, B. and Folliard, K.J. 2013a. “Alkali-Aggregate Reactivity (AAR) Facts Book.” FHWA-HIF-13-019, Federal Highway Administration. Thomas, M.D.A., Folliard, K.J., Fournier, B., Rivard, P., Drimalas, T. and Garber, S.I. 2013b. “Methods for Evaluating and Treating ASR-Affected Structures: Results of Field Application and Demonstration Projects – Volume II: Details of Field Applications and Analysis.” FHWA-HIF-XX-XXX, Federal Highway Administration. Thomas, M.D.A., Fournier, B. and Folliard, K.J. 2013c. “Selecting Measures to Prevent Deleterious Alkali-Silica Reaction in Concrete: Rationale for the AASHTO PP65 Prescriptive Approach.” FHWA-HIF-13-002, Federal Highway Administration. Potential options for mitigating AAR – treating the cause vs. treating the symptom TREAT THE CAUSE TREAT THE SYMPTOM Chemical Treatment • CO2 Lithium compounds Drying Sealants Cladding Improved drainage Crack Filling Aesthetics Protection (e.g. from Cl- ingress) Restraint Prevent Expansion Strengthen/Stabilize Relieve Stress Saw Cutting/Slot Cutting (accommodate movement) Mitigation Measures • Improved drainage • Application of coatings/sealers • Application of cladding • Crack filling • Application of lithium compounds • Application of restraint (FRP, etc.) • Saw cutting/slot cutting Aimed at lowering RH 5 6 7 8 9/9/2020 3 Pedneault, 1996 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 70 80 90 100 Relative Humidity (%) E xp a n si o n a t 2 Y e a rs ( % ) Siliceous Limestone Potsdam Sandstone Spratt Limestone Rhyolitic Tuff CSA Limit Little significant expansion if the relative humidity is maintained below about 80% Effect of Relative Humidity Reducing R.H. Vapour Liquid water AAR “ceases” at RH < 80 to 85% Silane Reducing R.H. ‘83 ‘84 ‘85 ‘86 ‘87 ‘88 ‘89 ‘90 -0.05 0.00 0.05 0.10 0.15 Acrylic Epoxy Silane Polymer Cement E xp an si on ( % ) Year Kojima et al. 1992 Summary of laboratory tests – post-treatment with lithium compounds Lithium compounds can reduce expansion of ASR-affected mortar/concrete in the lab (SHRP, Stokes et al (2000), Barborak et al (2004). Response appears to be aggregate-specific (similar to when used as admixture) BUT…. Data based on small specimens completely immersed in lithium Accelerated tests not related to real-world lithium applications… 9 10 11 12 9/9/2020 4 Using Lithium Compounds to Control ASR Alkali- silica gel Na,K-Si Na,K-Si Li+ Li+ Li+ Li+ Li+ Li+ Li+ Li+ Li-Si Li+ K + Li+ Li+ Li+ Li+ Na+ K + Na+ K + Without lithium present, a highly- reactive aggregate is attacked by the high pH solution, forming an ASR gel that absorbs water and causes the concrete to expand and crack. When using a sufficient dosage of lithium (nitrate) to control expansion, a highly-reactive aggregate is initially attacked by the high pH solution, forming an alkali silica gel. Lithium present in the pore solution then cation exchanges for the sodium and potassium in the gel, creating a non-expansive lithium-silica gel. Without lithium With lithium 13 Topical application of lithium nitrate – most common application method in the field… • South Dakota - U.S. 14 (near Wolsey) • Maryland - Bridge on I68 (near LaVale) • Minnesota – New Ulm • North Carolina – various • New Mexico – Albuquerque • Wyoming - Cheyenne • Delaware – Dover • Many others Topical Application Examples of topical treatments of pavements since 1995: • Very little monitoring • Little, if any, data showing whether lithium helped… FHWA Field Trials FHWA Field Trials State Structure Mitigation/Prevention Technique Alabama Historic bridge arch Silane sealer Arkansas Pavement Silane sealer Delaware Pavement Topical application of lithium nitrate Delaware Pavement Monitoring an asphalt overlay of pavement with lithium nitrate Hawaii Aggregates Testing aggregates and development of field exposure site Massachusetts Median barrier Silane sealers; topical application of lithium nitrate Massachusetts Aggregates Testing aggregates and development of field exposure site Maine Bridge abutments and piers FRP wrap; silane sealer; electrochemical application of lithium nitrate Texas Bridge Columns Electrochemical application of lithium nitrate; vacuum impregnation of lithium; silane sealers Texas Precast Bridge Girders Aggregate testing and investigation of specific mixture designs Vermont Bridge barrier walls Silane sealers 13 14 15 16 9/9/2020 5 The ASR Avengers FHWA Field Trials State Structure Mitigation/Prevention Technique Alabama Historic bridge arch Silane sealer Arkansas Pavement Silane sealer Delaware Pavement Topical application of lithium nitrate Delaware Pavement Monitoring an asphalt overlay of pavement with lithium nitrate Hawaii Aggregates Testing aggregates and development of field exposure site Massachusetts Median barrier Silane sealers; topical application of lithium nitrate Massachusetts Aggregates Testing aggregates and development of field exposure site Maine Bridge abutments and piers FRP wrap; silane sealer; electrochemical application of lithium nitrate Texas Bridge Columns Electrochemical application of lithium nitrate; vacuum impregnation of lithium; silane sealers Texas Precast Bridge Girders Aggregate testing and investigation of specific mixture designs Vermont Bridge barrier walls Silane sealers Control Silane Effects of silanes Silane Treated (by Mass Highways) RH < 80 percent (on average) FHWA Control Section Barrier Walls in Leominster, MA – Treated in June 2005 17 18 19 20 9/9/2020 6 Effects of silanes on expansion Canadian experience… Control Silane Use of Sealers (Quebec City) Courtesy of M.A. Bérubé, Canada Use of Sealers (Quebec City) Bérubé et al. (1998) 21 22 23 24 9/9/2020 7 Bérubé et al. (1998) Use of Sealers (Quebec City) FHWA Field Trials State Structure Mitigation/Prevention Technique Alabama Historic bridge arch Silane sealer Arkansas Pavement Silane sealer Delaware Pavement Topical application of lithium nitrate Delaware Pavement Monitoring an asphalt overlay of pavement with lithium nitrate Hawaii Aggregates Testing aggregates and development of field exposure site Massachusetts Median barrier Silane sealers; topical application of lithium nitrate Massachusetts Aggregates Testing aggregates and development of field exposure site Maine Bridge abutments and piers FRP wrap; silane sealer; electrochemical application of lithium nitrate Texas Bridge Columns Electrochemical application of lithium nitrate; vacuum impregnation of lithium; silane sealers Texas Precast Bridge Girders Aggregate testing and investigation of specific mixture designs Vermont Bridge barrier walls Silane sealers • 5-km section of I94 treated in Sept 2004 – 0.24 L/m2 (6 gal/1000 ft2) • Approx. 2/3 pavement area treated a second time in May 2005 • Approx. 1/3 pavement area treated a third time in Oct 2005 • Low, moderate & high severity of ASR Pavement in Idaho Field Studies – I94, Idaho 25 26 27 28 9/9/2020 8 Field Studies – I94, Idaho 0 20 40 60 80 100 120 140 0 2 4 6 8 10 Depth (mm) L ith iu m ( pp m ) p 462 w/c 1 p 462 w/o c 1 Lithium profiles in panel 462 after 3 treatments Field Studies – Barrier Wall, Leominster, MA Field Studies – Barrier Wall, Leominster, MA • Controls – 3 sets of 3 wall sections • Vacuum treatment – 4 sets of 2 wall sections • Topical treatment – 8 sets of 3 wall sections Field Studies – Barrier Wall, Leominster, MA Vacuum Treatment • 8 sections treated • Short Term: 0.25 hours* • Long Term: 7.25 hours* • 4 different types of treatments were applied: VA-1 and VA-2: Long term vacuum treatment using lithium on one side and short term vacuum treatment using lithium on opposite side VB-1 and VB-2: Short term vacuum treatment to both sides using lithium nitrate followed by a topical application of silane VC-1 and VC-2: Short term vacuum treatment to both sides using lithium nitrate VD-1 and VD-2: Short term treatment using lithium to both sides applied twice throughout the field application 29 30 31 32 9/9/2020 9 Field Studies – Barrier Wall, Leominster, MA Vacuum Treatment Field Studies – Barrier Wall, Leominster, MA Vacuum Treatment Field Studies – Barrier Wall, Leominster, MA • T1-A, B and C: Single Application Lithium • T2-A, B and C: Double Application Lithium • T3-A, B and C: Quadruple Application Lithium • T4-A, B and C: Double Application Lithium followed by 40% Silane Sealer (isopropyalcohol based) • T5-A, B and C: Masterseal 40 Silane sealer (isopropyalcohol based) • T6-A, B and C: Masterseal 20 Silane sealer (isopropyalcohol based) • T7-A, B and C: Enviroseal Silane sealer (water based) • T8-A, B and C: Dynacrete PIM+ (lithium silicate based) *Application rate information in report Field Studies – Barrier Wall, Leominster, MA 33 34 35 36 9/9/2020 10 Jersey Barrier Li-Spray 4x: T3C 01 0 0.01 0.02 0.03 0.04 0.05 0 5 10 15 20 Depth (mm) C o nc e n tr a tio n ( % ) Li Na K Field Studies – Barrier Wall, Leominster, MA 0 50 100 150 200 250 300 350 0 2 4 6 8 10 Depth (mm) L ith iu m ( p p m ) VA 1 VA 2 Long term vacuum treatment using lithium on one side and short term vacuum treatment using lithium on opposite side Effects of lithium nitrate on expansion Houston columns – field trial 0 50 100 150 200 250 300 350 0 2 4 6 8 10 Depth (mm) L ith iu m ( p p m ) VA 1 VA 2 37 38 39 40 9/9/2020 11 ElectrochemicalVacuum No topical applications of lithium were performed for this field trial (based on minimal depths of penetration in ID, MA, and lab) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Depth(mm) P er ce n ta g e in C o n cr et e Houston column (#45) – Depth of lithium penetration for vacuum treatment Houston Columns: Core 46-1 @ Rebar Plan Side View Column was treated electrochemically with lithium for 8 weeks prior to extraction of core located over rebar 46-1 @ Rebar 0.00 0.05 0.10 0.15 0.20 0.25 0 0 --0 3 0 6 --0 9 1 2 --1 5 1 8 --2 1 2 4 --2 7 3 0 --3 3 3 6 --3 9 4 2 --4 5 4 8 --5 1 Depth(mm) P e rc e n ta g e in C o n cr e te Li Na K Profile of Alkali Ions (Li, Na & K) in Columns Subjected to Electrochemical Treatment 41 42 43 44 9/9/2020 12 Houston columns Cracking of Column 35 – after electrochemical lithium treatment Summary of lithium penetration data*… State Element Treatment method Depth to which “threshold” level of lithium was measured (mm) ID (field-treated) Pavement Topical (3x) 1 – 4 ID (lab-treated) Pavement Topical (3x) 1 – 5 MA Barrier wall Topical (4x) 0.5 – 1.5 MA Barrier wall Vacuum (“long- term”) 2.5 – 3.5 TX Column Vacuum 8 TX Column Electrochemical 50 (to depth of rebar) *Similar experience with topical applications in lab…. Jobe control Jobe (ponded with lithium for 8 months) 45 46 47 48 9/9/2020 13 Jobe (sprayed every week for 32 weeks – 4 gallons per 1000 sq. ft each treatment) Jobe Exposure Blocks - Average Expansion 0.0% 0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0.7% 0.8% 0 100 200 300 400 Time (Days) A v er ag e E x p an s io n ( % ) Control Block LiNO3 (Renew) Topical Spray LiNO3 (Renew) Ponding Application Effects of lithium spraying or ponding on expansion of ASR exposure blocks Jobe Exposure Blocks - Average Top Surface Expansion 0.0% 0.2% 0.4% 0.6% 0.8% 1.0% 0 50 100 150 200 250 300 350 400 Time (Days) A ve ra g e E xp an si o n ( % ) Control Block LiNO3 (Renew) Topical Spray LiNO3 (Renew) Ponding Application Effects of lithium spraying or ponding on expansion of ASR exposure blocks Conclusions • Silanes were found to be highly effective when applied to highway barriers – jury is still out on effects on large columns • Topical treatment of lithium nitrate does not appear to be effective due to lack of penetration • Vacuum impregnation has also yielded minimal penetration of lithium nitrate. • Driving lithium nitrate into reinforced columns was effective using electrochemical method, but will increased OH-, Na+, and K+ exacerbate ASR at rebar surface? • Long-term ponding and multiple topical applications of lithium in exposure blocks has been ineffective in reducing expansion/cracking • It is always best to prevent ASR in the first place!!! 49 50 51 52 8/30/2020 1 Fall 2020 National Concrete Consortium Webinar Lightweight Cellular Concrete: Industry Experience Greg Halsted, P.E., Manager, Pavements and Geotechnical Markets September 1, 2020 • Greg Halsted is the Manager of Pavements and Geotechnical Markets for the Portland Cement Association (PCA). • He is responsible for expanding the market share for use of portland cement in all paving and engineered cement applications. • Greg has over 35 years of engineering experience, including 17 with the Georgia DOT and 18+ with cement and concrete associations. • He has a B.S. degree in Civil Engineering Technology from Southern Polytechnic State University and is a registered professional engineer. • Greg has a strong background in pavement materials, design, construction, and testing, as well as cement and concrete promotion, education, and advocacy. About the Presenter • Introduction • Applications • LCC - Yesterday • LCC - Today • LCC - Tomorrow • Questions INTRODUCTION 8/30/2020 2 Cement-Based Paving/Geotech Materials Water Content C em en t C o n te n t Roller Compacted Concrete Conventional Concrete Soil-Cement Flowable Fill Cement Stabilized Subgrade and Cement-Modified Soil Full-Depth Reclamation Cement- Treated Base Pervious Concrete Lean Concrete Base Lightweight Cellular Concrete Precast Concrete Lightweight Cellular Concrete • Lightweight cellular concrete, or LCC, is a mixture of portland cement, water, and air that can act as a lightweight, strong, durable, and inexpensive soil or fill replacement for geotechnical applications • LCC saves time, money, and natural resources by replacing aggregates with air bubbles in numerous project applications • Cementitious materials encapsulate the air bubbles, then dissipate leaving a void structure as a replacement to traditional aggregate • Cellular concrete differs from conventional concrete in the methods of production, the density of the material, and the extensive range of uses Pore Structure when Cured Methods of Foam Incorporation Preformed (produced by a foam generator) Agitated (produced by the mixing action of a concrete mixer) ACI 523 ACI 229 Low-Density Cellular Concrete (LDCC) Controlled Low-Strength Material (CLSM) American Concrete Institute Standards 8/30/2020 3 “Concrete made with hydraulic cement, water, and preformed foam to produce a hardened material with an oven dry density of 50 lb/ft3 (800 kg/m3) or less.” LCC as Defined by ACI 523 oven-dry density usual range of compressive strength at 28 days lb/ft3 kg/m3 psi MPa 20 to 25 320 to 400 70 to 125 0.48 to 0.86 25 to 30 400 to 480 125 to 225 0.86 to 1.55 30 to 35 480 to 560 225 to 350 1.55 to 2.41 35 to 40 560 to 640 350 to 450 2.41 to 3.10 40 to 50 640 to 800 450 to 750 3.10 to 5.17 Density and Strength Ranges per ACI 75 percent of the volume is foam Typical Guidelines for LCC Mixes • Designed to replace traditionally compacted backfill • Not designed to be the driving or wearing surface, nor to be used in place of a structural concrete design Important to Remember about LCC 8/30/2020 4 APPLICATIONS • Wall configuration backfill • Annular fills for tunnels and culverts • Tunnel abandonment • Fill for underground utilities • Void fills • Soft soil remediation • Slope stabilization • Tanks and pipeline abandonment • Fill around conduits and pipes Typical Applications 50-foot vertical fascia walls Vertical Fascia Walls Grade Separations 8/30/2020 5 Retaining Wall Backfill Culvert Applications Backfill around Utilities Slope Stabilization 8/30/2020 6 • Flows into every nook and cranny • No vibration or compaction required • Easily excavatable for maintenance Utility Trench Backfill and Void Fill LCC - YESTERDAY 1900s Originally invented in Europe 1950s ACI Guidelines and USACE tested 1990s Widely approved by DOTs and other agencies A Brief History of LCC STRUCTURE® Magazine (December 2014) • Cellular Concrete • Scott Taylor, P.E., President, Throop Cellular Concrete • “…the civil/structural engineering world is starting to realize the vast benefits of cellular concrete.” • “We are seeing the variety of uses expanding daily by enthusiastic and creative engineers everywhere.” • “Many agencies and engineers are learning about the benefits, and the cellular concrete industry hopes the product will soon be a standard product in all 50 states.” 8/30/2020 7 • “The infrastructure sector is estimated to account for the largest market share in the cellular concrete market and this trend is projected to continue…” • “Cellular concrete is replacing the traditional materials in the construction industry and it is easily available in the market, owing to their lightweight and better-quality properties.” Cellular Concrete Market (2015 - 2020) LCC - TODAY ASTM C495 ASTM C796 “Standard Test Method for Compressive Strength of Lightweight Insulating Concrete” “Standard Test Method for Foaming Agents for use in Producing Cellular Concrete using Preformed Foam” ASTM C869 “Standard Specification for Foaming Agents Used in Making Preformed Foam for Cellular Concrete” ASTM Test Methods for Quality Assurance high production self-contained unit for larger volume projects mobile mixing units self-contained trailer wet batch system Types of On-Site Installation Equipment 8/30/2020 8 12 with Specifications States with Specifications for LCC 12 with Specifications 4 with Provisions States with Specifications for LCC • California Special Provision – 19-10 “Cellular Concrete Lightweight Embankment Material” • Colorado Section 206.02(a)2 “Structure Backfill (Flow-Fill)” • Florida Section 121 “Flowable Fill” • Illinois Section 1029 “Cellular Concrete” • Indiana Section 216 “Cellular Concrete Fill, CCF” • Iowa Special Provision – 150271 “Lightweight Foamed Concrete Fill” • Minnesota Section 2519 “Cellular Concrete Grout – Controlled Low Strength Material (CLSM)” • Missouri Section 621 “Flowable Backfill” • Nevada Section 207.02.02 “Slurry Cement Backfill” • New York Section 204-1.02 “Lightweight Concrete Fill” • Oregon Special Provision – 00444 “Low Density Cellular Concrete” • Rhode Island Section 603 “Controlled Low Strength Material (CLSM)” • South Carolina Section 210 “Flowable Fill” • Texas Special Provision – 03310 “Low Density Cellular Concrete for Microtunnel Backfill” • Washington Section 2-09.3(1)E “Backfilling” • Wyoming Supplementary Specification – 600D “High Density Polyethylene (HDPE) Liner Pipe” Alternative Terminology LCC - TOMORROW 8/30/2020 9 Transit Mixers and LCC • Guide to Lightweight Cellular Concrete for Geotechnical Applications • Technical Advisory Committee (TAC) effort • Information on common uses and conceptual guidance, as well as design guidelines, for construction professionals / design engineers • Chapter 1 – Introduction • Chapter 2 – Physical Properties • Chapter 3 – Geotechnical Design Considerations • Chapter 4 – Mixture Design • Chapter 5 – Construction • Chapter 6 – Inspection, Testing, and Maintenance • Specifications for construction of LCC fill Currently in Development GUIDE TO SOON IN 2020 Lightweight Cellular Concrete for Geotechnical Applications • Aerix Industries • California Nevada Cement Association • California State University – Fullerton • Cell-Crete Corporation • Cellular Concrete Inc. • CEMATRIX • Elastizell Corporation of America • National Concrete Pavement Technology Center • The Reinforced Earth Company • Richway Industries, Ltd. • RW Henn LLC • Scott Taylor • University of Illinois at Urbana-Champaign • University of Utah Acknowledgements • Broad range of densities • Economical • Versatile • Easily placed • Rapid installation • Durable • Excavatable • Permanent and stable • Environmentally friendly Concluding Comments 8/30/2020 10 www.cement.org Fall 2020 National Concrete Consortium Webinar Lightweight Cellular Concrete: Industry Experience Questions / Comments / Discussion September 1, 2020 9/4/2020 1 About the Presenter • James Krstulovich is the Engineer of Concrete & Soils for the Illinois Department of Transportation. • He holds a Bachelor of Science degree in Civil Engineering from the University of Illinois at Urbana-Champaign and is a registered professional engineer in Illinois. • His duties with the Department include researching emerging concrete and cementitious technologies, developing specifications, and implementing testing standards and procedures. • Areas of professional interest include: mix design methodology, concrete durability, materials-related distress, research implementation, and specifications development, with an emphasis on performance-related criteria. DEVELOPING SPECIFICATIONS FOR LIGHTWEIGHT CELLULAR CONCRETE WHERE DID WE START? SECTION 543 INSERTION LINING OF CULVERTS • • • m ay s- m cs i.c om ‘BASIC’ SPECIFICATIONS SECTION 1029, CELLULAR CONCRETE • • • • • c el lu la rc on cr et e. co m 9/4/2020 2 ‘BASIC’ SPECIFICATIONS SECTION 1029, CELLULAR CONCRETE • • • • • • • • au to m at ic co m pr es si on m ac hi ne s. co m 4x8 in. 4x8 in. 6x12 in. 3x6 in. QUALIFIED PRODUCT LIST QPL FOR FOAMING AGENTS • • • • • LIGHTWEIGHT CELLULAR CONCRETE FILL STARTED TO SEE INCREASED USE OF CELLULAR CONCRETE FOR MSE WALL FILL • • • • ge op ra c. ne t LIGHTWEIGHT CELLULAR CONCRETE FILL SOME EXAMPLES OF PROBLEM SPECS • • • • • • 9/4/2020 3 LIGHTWEIGHT CELLULAR CONCRETE FILL WE REALIZED WE NEEDED TO STANDARDIZE THE DEPARTMENT’S APPROACH TO LCCF • • LIGHTWEIGHT CELLULAR CONCRETE FILL DEVELOPED NEW SPECIAL PROVISION IN 2016 • • • • LIGHTWEIGHT CELLULAR CONCRETE FILL NEW SPECIAL PROVISION (CONT’D) • LIGHTWEIGHT CELLULAR CONCRETE FILL NEW SPECIAL PROVISION (CONT’D) • • 9/4/2020 4 LESSONS LEARNED EXPERIENCED AND PERCEPTIVE PRACTITIONERS MAY HAVE ALREADY CAUGHT SOME POSSIBLE PROBLEMS WITH OUR NEW SPECIAL PROVISION... LESSONS LEARNED STRENGTH TESTING • • • • “If cellular concrete made using preformed foam is being tested, moist cure the cylinders from day 2 to day 25. At day 25 air dry the cylinders for 3 days at a temperature of 21 ± 6 ºC [70 ± 10 ºF] and a relative humidity of 50 ± 10 %.” LESSONS LEARNED STRENGTH SPECIMEN CURING • • • • • • Also experimented with fan drying for final 24 hrs LESSONS LEARNED STRENGTH TESTING • • “Continuously apply the load without shock at a constant rate such that the maximum load will be reached in 65 ± 15 s.” • • 9/4/2020 5 LESSONS LEARNED STRENGTH TESTING • • • LESSONS LEARNED MOVING FORWARD • • • • • QUESTIONS? EMAIL ME FOR A COPY OF OUR SPECIFICATIONS • | |
| Joints | 👤 Kevin McMullen 👤 Bill Cuerdon | Concrete Pavement Technology Tuesday Webinar | 2020 |
| 2020-08-18 | WELCOME TO THE 2020WCPA ANNUAL CONCRETE PAVEMENT WORKSHOP! Concrete Pavement Joint Design, Layout and ConstructionAugust 18, 2020 Kevin W. McMullen, P.E. President Wisconsin Concrete Pavement Association What are we going to cover? • Fundamentals of why we joint concrete • Joint Spacing • When do we saw? • How deep do we saw? • Types of Joints • Joint Sealing • Load Transfer • Transverse Construction Joints Why Joint Concrete Pavements? Concrete Shrinks! Drying Shrinkage Hydration Uses Water Thermal Shrinkage Hot then Cold HOT AT SET = Chemical Shrinkage COOLED OFF Shrinkage + Restraint = CRACKS!?! HOT AT SET, HIGH MOISTURE, UNHYDRATED CEMENT COOL, DRY, HYDRATED CEMENT TEFLON | No Friction/Restraint If no restraint With restraint Subgrade/Subbase | Restraint Why Joint Concrete Pavement? • Without joints, natural transverse & longitudinal cracking would form about like this… 40-80 ft 15-20 ft Why Joint Concrete Pavement? • We place joints at a slightly shorter spacing to prevent natural cracking… Why Joint Concrete Pavement? • Other reasons we joint concrete pavements: Help the traffic engineers define lanes Divide pavement into construction lanes or increments. Accommodate slab movements. Provide load transfer via placed dowels. Provide uniform sealant reservoir. TYPES OF JOINTS Types of Joints • Joint types: • Contraction • Construction • Isolation (and, if necessary, expansion) • Each can occur in either the transverse or longitudinal directions. • Also specialty joints (e.g., transitions, terminal joints in continuously reinforced, etc.). Types of Joints Transverse Contraction: Types of Joints Longitudinal Contraction: Types of Joints Transverse Construction: Types of Joints Longitudinal Construction: Types of JointsIsolation: Examples of Locations TB019P Joint Spacing Joint Spacing Evolution Short Joints Long Joints JOINT SPACING • 2 x T (Granular Sub-base) • 1.5 x T (Stabilized Sub-base) • Experience Formula for Maximum Joint Spacing MECHANISTIC l = radius of relative stiffness, in. E = modulus of elasticity of the concrete, psi h = slab thickness, in. k = modulus of subgrade reaction, psi/in. = Poisson’s ratio for concrete, usually 0.15 L/l of 7 works in field; LIMIT L/l to about 4-5 to be conservative = 12 1 Example with Radius of Rel. Stiffness E = 4 x 106 psi h = 8 in. k = 100 psi/in. = 0.15 = 12 1 = 10 812 1 0.15 100 = 36.35 . Slab Length is 4 or 5 time this: = 4 = 4 36.35 .= 12.1 = 5 = 5 36.35 .= 15.1 But there is an easier way… Example with Radius of Rel. Stiffness E = 4 x 106 psi h = 8 in. k = 300 psi/in. = 0.15 = 12 1 = 10 812 1 0.15 300 = 27.62 . Slab Length is 4 or 5 time this: = 4 = 4 27.62 .= 9.2 = 5 = 5 27.62 .= 11.5 But there is an easier way… Formula for Maximum Joint Spacing EMPIRICAL ML = T x Cs ML = Maximum length between joints (in. or cm) T = Slab thickness (in. or cm) Cs = Support constant Use 24 for subgrades or unstabilized [granular] subbases; Use 21 for stabilized subbases (ATB, CTB, lean concrete) or existing concrete or asphalt pavement; Use 12 to 15 for thin bonded overlays on asphalt 0% 10% 20% 30% 40% 50% 60% 70% 80% 0 10 20 30 40 50Traffic, million ESALs 20 ft 18 ft 17 ft 15 ft Effects of Joint Spacing Coefficient of Thermal Expansion Limestone Siliceous Gravel Temperature Sensitivity Other Consideration: Concrete Aggregate Other Joint Spacing Issues • Random? Don’t Do it!!!! • Old concept • Suspensions of vehicles has changed • Skew? Don’t Do It!! • Diagonal effect • An effort to prevent faulting in undoweled joints • Typical was 1:6 skew • Just delayed the onset of faulting Joint Spacing Recommendations For Streets, Roads, and Highways: • Use ML = T x Cs • Keep ratio of transverse to longitudinal spacing at less than 1.5; square is best • Keep maximum spacing of transverse joints to 15 ft (4.57 m) for plain concrete unless local history shows longer panels work (e.g., low CTE aggregate) How deep do we saw? Joint Depth Recommendations • Transverse • T/4 on unstabilized • T/3 on stabilized • Longitudinal • T/3 • Timing is a factor • Early-entry sawing may allow for sawing depths of T/6 to T/5, but at least 1.25 in. (32 mm) deep • If start to see dust from cut, consider reverting to a cut depth of T/4 TRANSVERSE LONGITUDINAL T/4 T/3 T/3 T/3 Proper Location, Time & Depth = Joint Activated Over Dowel Bars Load Transfer Dowels: Critical Structural Components of Jointed Concrete Pavement• Provide Load Transfer • Prevent joint faulting • Reduce slab stresses • Reduce slab deflections, potential for erosion of support • Restraint of Curl/Warp Deformation • Influence Dowel-Concrete Bearing Stress, Faulting • Dowel corrosion can cause joint spalling, joint lock-up and associated distresses WisDOT Dowel Bars • Dowel bars • 18-inches in length • Spaced 12-inches center to center across the transverse joint • Diameter usually ranges from 1-inch to 1.5-inches depending on the slab thickness WisDOT Dowel Bar Baskets Dowel Bar Baskets Dowel Bar Tolerances • Dowel bar position and alignment are critical • Dowel misalignment • Significant effect on pavement performance resulting in cracking • Dowel bar alignment tolerance • ¼ -inch/foot or less in the vertical and horizontal plane • Common misalignment specifications: • Within 1 inch of the planned transverse location and depth • Within 2 inches of the planned longitudinal location. • Parallel to the pavement surface and centerline within a tolerance of 1/2 inches in 18 inches. • This tolerance allows for whole inch baskets to be used for half-inch pavement thicknesses (Example: 9-inch basket used in a 9.5-inch pavement) Baskets or DBI • DOWEL BAR INSERTER (DBI) • Research shows inserters can be just as accurate or more so than baskets • Research also shows that baskets can be placed as inaccurate as inserters too. • Both methods have their place and advantage Dowel Length • Typically 18 in (since 1950s) • Based on embedment requirements to match behavior of Timoshenko 1925 analysis (semi-infinite embedded bar) • A few states successfully use shorter dowels in new construction (e.g., 15 inches in MN) • Shorter embedment lengths are supported by research dating to 1950s DowelCAD 2.0 • FREE software that predicts pavement behaviors based on different round and elliptical dowel bar spacings and configurations. • Results can help designers significantly decrease embedded steel content (and costs) without compromising performance! • Program based on finite element analyses. Dowel Bar Options High Performance Concrete PAvement Dowel Bars • 316L Stainless Steel Cladding • 316L Stainless Steel Tubes • Solid Stainless Steel • UNS Z41121 Zinc Alloy Cladding • CRT Bar – Conventional steel with fiber composite outer coating • Armour Coat Solid Dowel Bar – Simplex • G90 Galvanized O-Dowel Tube HPC Dowel Bars HPC Dowel BarsG90 Galvanized O-Dowel Tube HPC Dowel BarsArmour Coat Solid Dowel Bar – Simplex New O-Dowel by Schenk Industrial • Lightweight tubular steel • 11 gauge • Welded flat rolled carbon steel tubular • G40 Galvanized coating • Standard epoxy coating • “One man dowel basket” Tie Bars Tie Bar Design Concepts • Purpose: hold longitudinal joints tight • Design tools • 1986/1993 AASHTO Guide • ACPA M-E Tie Bar Design (apps.acpa.org) • Generally overdesigned • Too much steel! We are often reinforcing the joints (counteracting saw cuts) rather than tying them! • Note German practice: 2 ties per 15-ft panel for new construction • Tie bar length is typically selected to develop full tensile capacity of the bar rather than required tensile capacity • Bearing stress (selection of bar size) can be important for butt joints Tie Bar Design – Subgrade Drag Theory h Force in Steel = Force in Concrete Frictional resistance As = FLhDw / [fs x (2/3)] As= area of steel per lineal foot (in2)fs= allowable working stress (lb/in2)F = coefficient of friction factor L = slab length (in.) D = distance to free edge (in.) h = slab thickness (in.) w = concrete unit weight (lb/in3) PROBLEMS: • Based on drag • No temp drop from set • Free edge does not apply after 2+ lanes • Simplistic method of modeling slab/base friction • Large safety factor (2/3) • Does not account for displacement of subbase Tie Bar Installation • Commonly mechanically inserted when paving multiple lanes • Tie bar baskets used as well • Bent tie bars are used at longitudinal construction joints to accommodate future stages • Verify longitudinal positioning: • Do not place tie bars across a transverse joint. The insertion of the tie bars may conflict with the insertion of the dowel bars causing the dowel bars to become misaligned • Tie bars installed in new concrete are #4 or # 5 deformed bar, 30 or 36 inches long spaced at 36-inches center to center depending on the pavement thickness • Bent #4 deformed bars as noted WisDOT Tie Bars WisDOT Tie Bar Placement • WisDOT Standard Detail Drawing (SDD). Transverse Construction Joints Construction Joints (Headers) • Header joints (also known as transverse construction joints) are built at the end of a section of pavement • Must be constructed at the end of a day’s run • Constructed due to significant paving delays • Either formed or sawed • No way to account for in layout planning • If next to previously placed pavement, best to match header with existing transverse joint Formed Header • Either two-part form with dowels protruding through form or false-dowels attached to form face and dowels inserted upon form removal; consolidate concrete well at form Formed Header Sawed Header • Paving continued through of header, pavement sawed back, dowel/tiebar holes drilled, and dowels/tiebars installed Joint “Sealing” or Joint “Filling” Joint Sealants • Accepted definition:Sealants minimize infiltration of surface water & incompressiblesinto the joint system. • Erroneous definition:Sealants prevent infiltration of surface water & incompressibles into the joint system. History & Background Joint Filling Specs • Joint performance issues • Posted speeds and tire noise • Curb and gutter confining debris on roadway • Joints filling with incompressibles and spalling occurring • Urban pavements less than 45 mph with curb and gutter JOINT LAYOUT Intersection Jointing • Develop a jointing plan • Bird’s eye view • Follow ACPA’smethod • Be practical! ACPA Publication IS006 “Intersection Joint Layout” • 10-step method • Special situations • Added lanes • Islands • Skewed intersections • Utility fixtures The Challenge of the Intersection in 10 steps 3 Easy Rules Keep it Short! Keep it Simple! Keep it Practical! Things to Ensure • Match existing joints or cracks • Place Joints to meet in-pavement structures • Error on the short side • Exact spacing not important • Consider non-obvious factors • Avoid acute angles • Meet pavement width changes • Length to Width Ratio: • Target 1.25 • Do Not exceed 1.5 Things to Avoid • Slabs < 1 foot wide • Slabs > 15 feet wide • Angles < 60º (<90º is better) • Interior corners (L-shaped slabs) • Odd shapes (keep slabs square or pie-shaped) In-Pavement Objects 2018 Concrete Pavement Jointing Short Course Round Inlet Boxout Square Inlet (no boxout) 2018 Concrete Pavement Jointing Short Course Square Square w/ Fillets Diagonal Circular Isolate Perimeter Telescoping 2018 Concrete Pavement Jointing Short Course Good Practice! 2018 Concrete Pavement Jointing Short Course THANK YOU and happy to follow up with any questions Main Website | acpa.org Free Apps | apps.acpa.org Resources | resources.acpa.org Your Local Contact | local.acpa.org Kevin W. McMullen, P.E. President Wisconsin Concrete Pavement Association kmcmullen@wisconcrete.org (608)209-0878 www.wisconcrete.org 8/20/2020 1 Jointing Pavements In New York State CPTech Center – ACPA Webinar Series August 18th, 2020 Bill Cuerdon ACPA‐NYS bcuerdon@pavement.com (518) 928‐1835 Reminder New York Examples Local Experience Matters Always Contact Your ACPA Chapter 8/20/2020 2 8/20/2020 3 8/20/2020 4 Concrete Pavement Slab Geometry Rules of Thumb • NYSDOT Uses AASHTO 93 • L(feet) = 1.5 ‐ 2.0 x Thickness (inches). Just L? • NYSDOT: Lmax = 15’ Wmax = 13’ Lmax = Wmin x 1.33 Lmin = Wmax ÷ 1.33 • Pavement ME: Geometry is an Input 8/20/2020 5 8/20/2020 6 Manholes and Drainage Structures 8/20/2020 7 8/20/2020 8 8/20/2020 9 Roundabouts 8/20/2020 10 8/20/2020 11 8/20/2020 12 8/20/2020 13 8/20/2020 14 8/20/2020 15 8/20/2020 16 8/20/2020 17 8/20/2020 18 Ramps and Gores 8/20/2020 19 8/20/2020 20 8/20/2020 21 Joint Sealing •Fill ‘em up •ASTM D 6690 Type IV •Fill Is NOT Less Quality 8/20/2020 22 Essential Concrete Pavement Websites acpa.org wikipave.org apps.acpa.org cptechcenter.org resources.acpa.org concretepavements.org fhwa.dot.gov/pavement pavementdesigner.org nrmca.org paveahead.com pna‐inc.com/tcp Joints Webinar – Questions and Answers The questions submitted during the webinar follow with answers that our speakers have provided. Additional resources are available at http://www.acpa.org/wp-content/uploads/2017/11/IS006E- Intersection-Joint-Layout.pdf 1. Do you believe mobile GPR may replace MITScan? Florida BC I would rather say “complement” than “replace.” In New York, we’ve had “the best” results with the MIT Scan, but we have encountered some limitations. Specifically, determining dowel alignment in An unbonded overlay atop a reinforced pavement, A pavement on a slag aggregate subbase, Baskets without the shipping wires being cut, and Dowels closest to longitudinal joint ties Contractors have used GPR in some of those situations, but it was not quite as precise. I think it’s reasonable to assume that technology will develop and improve to determine dowel alignment and any method that can provide accurate and precise results will help the concrete industry and provide our agency-owner partners with great data. KWM I do not believe that ground penetrating radar will be used as a tool to replace MIT Scan. MIT Scan builds a three dimensional model of the dowel bar that allows for a very accurate idea on the position of the dowel. I have not seen a GPR device and data output that can do what the MIT In addition, the MIT Scan device has been endorsed by the Federal Highway Administration, the American Concrete Pavement Association and many state DOTS and tollway authorities as the tool for use in measuring the accuracy of the dowel placement. See FHWA CPTP Tech Brief FHWA-HIF-07-021, published in January 2007 and Guide to Dowel Load Transfer Systems for Jointed Concrete Pavements published by the NCPTC in September 2011 2. Which dowel bar translation is most critical? Florida BC The one that’s farthest out of spec. That said, probably vertical tilt and horizontal skew because they will lock the joint. Longitudinal translation of an 18” long dowel needs to be severe to increase bearing stress to the point it will damage the joint. Upward vertical translation is more critical than downward. New York is +0”, -1” on vertical translation. KWM Horizontal skew and vertical tilt are the key parameters. Side Shift and vertical deviation still allow for the concrete pavement to expand and contract around the http://www.acpa.org/wp-content/uploads/2017/11/IS006E-Intersection-Joint-Layout.pdf http://www.acpa.org/wp-content/uploads/2017/11/IS006E-Intersection-Joint-Layout.pdf dowel. Horizontal skew and vertical tilt can lock the joint up completely and prevent movement. See http://www.acpa.org/wp-content/uploads/2020/07/18-11-15-ACPA- Dowel-Alignment-Guide-Spec.pdf 3. Why do they still make dowels 18 inches long? Shorter dowels should work just as well and would save cost, Florida BC Agree fully. In fact, New York uses 14-inch long dowels in precast slabs and pavement repairs. It is quite easy to see that they are properly placed in those applications. They are still 18” long because agencies fear too much longitudinal translation and/or misplaced saw cuts. 18 inches is a big, entrenched factor of safety. KWM AS I mentioned in the presentation 18 -inch dowels are nothing but history and tradition. Research going back as far as the 1920s established the 18-inch length. In more recent times this dowel length provides a good factor of safety that there is enough embediment length for performance. I also indicated that MN is currently using 15 inches and I see more companies and DOTs looking at this. 4. Bill, can you please expand on the material that you used to fill the joints? California, Dulce Rufino Feldman BC The material is a hot-applied, asphalt-based sealant meeting ASTM D 6690 Type IV. ASTM D 6690 Type II is the old D 3405. Seems like everyone who had a “3405” material also had a “modified 3405” for concrete joints. D 6690 Type IV is the “modified D 3405.” Type IV has a greater extension than Type II at -29°C. KWM Wisconsin specifications require the use of hot pour asphalt joint sealer meeting the requirements of ASTM D6690, type II. 5. On the joint design for the gore area where you tied on one the most loaded side only, did you have simply a construction joint without tie bars OR did you specify an isolation joint to prevent sympathy cracks? California BC It is a butt joint. No key, ties, or board. We apply form oil or plastic sheeting to the first placement and let the second placement shrink ever so slightly away from the first. We typically do not use expansion board (isolation board), except in cold weather closure pours. In the cold weather, we need the board to take up a little space. In the cold, the surrounding concrete shrinks a little, so the “hole” is gets little bigger. So we end up putting in a touch more concrete in the hole than we would in warmer weather. Then, come warm weather, if there’s no board, there isn’t enough room for expansion, and we get blow ups. http://www.acpa.org/wp-content/uploads/2020/07/18-11-15-ACPA-Dowel-Alignment-Guide-Spec.pdf http://www.acpa.org/wp-content/uploads/2020/07/18-11-15-ACPA-Dowel-Alignment-Guide-Spec.pdf When we’ve used board in the warm weather, we seem to end up with wide joints. The hole is smaller, a little less concrete goes in, and what goes in shrinks. That shrink is on top of the ½” or ¾” board width. 6. What is your recommendation for maximum transverse and longitudinal joint width? California BC I’m assuming you mean sealant reservoir width. For NYSDOT sealing with ASTM D 6690 Type IV, we just need a reservoir that’s wide enough to accept the sealant. A typical ⅛” wide first stage will not accept sealant. ¼” seems to do the trick. When we used silicone sealant, we chose ⅜” (10 mm) based on our typical aggregates and slab lengths. That allowed 100% expansion. Then, we’d bevel the reservoirs ⅛” (3 mm) on each side to get the silicone beneath the surface of the pavement to protect it from traffic. So the entire width was ⅝” (15 mm), which, with joint activation, became just enough for tire slap. KWM Maximum joint width is nothing more than the width of the saw blade cutting the joints. So, approximately 3/16 to ¼ of an inch 7. You talked about filling the joints right at the end and did not spend much time on it. It seems you simply "filled" the joints to avoid other "evil" material to penetrate..., California BC When you get a guy from Wisconsin and a guy from New York together, you shouldn’t ask too many questions about joint sealing. Sparks can fly 😉😉. Seriously, joint sealing has a lot of opinion and empiricism associated with it. California’s experience with sealant is going to be quite different from New York or Wisconsin. When NYSDOT used silicone, we also used backer rod. This left a void under the backer rod that had the potential to hold water and salts. If there is enough water to saturate the concrete, freezing and thawing can deteriorate the joint. If we fill the entire joint, there is less room for water and less potential to saturate the concrete. Also, if we fill the joint, there is less room for incompressibles. My experience in New York is that any space taken by D 6690 Type IV is better than space filled by water or road debris. The adhesion in our method is only in the top 1” deep reservoir. And it may very well be that we do not have adhesion on both sides of the joint. But the sealant, when it is in the first stage cut, stays in there with the adhesion we do get in the clean, dry reservoir. Plus, the self-leveling silicones just didn’t seem to stick as well as the ones that had to be tooled into place. Finally, we can grind through the D 6690 material, but grinding through silicone was certain loss of sealant. KWM Our approach in Wisconsin is that we are filling the joints for the sole purpose of keeping incompressibles out. We do not believe that we can seal joints to keep water out. Filling also provides the reduce capacity for water to enter the joints. 8. "Not tied" and adjacent is also isolated to avoid sympathetic cracking or truly adjacent, not tied and not isolated but a plastic bond breaker or form oil avoids bonding? North Carolina BC Yes. Please refer to number 5 above. The plastic or form oil both seem to be sufficient to stop bonding. Plastic is for sure effective. The second placement will shrink ever so slightly away from the first if we ensure they do not bond. And that seems sufficient to stop the sympathy cracks. If they bond, it is more likely that they will crack each other. KWM I am consistent with Bill Cuerdon on this one. A construction joint is all that is needed in many cases. The introduction of expansion joint material seems to introduce the potential for wide joints and water/durability issues with the concrete. 9. What is your opinion on reducing the number of dowel bars across the 12-ft lane? In particular, removing the centerline dowel? Or another option of only using 4 dowels per wheelpath? Pennsylvania BC Well, I know those Pennsylvania truckers really stay exactly where they’re supposed to. But up here, it seems like our truckers drive like they’re in a scene from Terminator. Seriously, and it’s strictly opinion, but I’m reluctant to remove the center dowels. I’m old and slow to change. It seems like trucks weave. It seems like we’d need to know how many truck wheels are over those center dowels, or lack thereof, to do a proper design. KWM I think this is absolutely an approach to load transfer system designs that we should be looking at and evaluating. There has been a number of research efforts that have looked at this and concluded that some of the dowels in the center of the lane are not doing any work or a small amount of the work transferring the load. A great tool for analyzing this is the ACPA DowelCAD software. It is a very simple and good visual tool of some of the most popular approaches to this in the past. Key is that we do it with knowledge. None of us wants to put something out there that reduces the life of the pavement. But, we should be optimizing our design approach. Significant dollars could be saved. 10. What type of subbase do you use below your PCC pavement and what impact have you found it has on dowel misalignment when using baskets, Illinois BC New York uses dense graded aggregate base and I presume that it has no effect on dowel alignment. KWM The vast majority of the concrete pavements in Wisconsin are on top of 6 inches of dense graded base aggregate. In many cases, there are additional layers of granular bases underneath. The key is the dense graded base and the ability to anchor baskets for good alignment of dowel bars. Unfortunately, the longtime policy of the Wisconsin Department of Transportation is to allow the contractors to keep the shipping wires intact. We had research back in the late 80s and early 90s that showed the dowels were more accurately placed when they were kept intact. Keeping the wire uncut distorts the accuracy of the MIT Scan device, so we have no modern day data on the accuracy of placement of dowel bar baskets. 11. How effective is Corrosion Resistant Alloy Steel (MMFX, or ChromX) for rebars? Are they better than epoxy coated rebars in terms of corrosion resistance? New York BC I would direct you to Willie Feliciano in the NYSDOT Materials Bureau. KWM I do not have any direct knowledge of this product. And, this question underscores the need for the revision of AASHTO T253 and M254 standards. Upon completion of the effort we would be able to reference all dowel products on their ability to transfer load and their corrosion resistance properties. 12. I often see highway concrete pavement densely reinforced longitudinally & horizontally. Concrete itself has shear strength enough to support vehicular wheel load as far as I know. Also, once a tiny micro crack started, then nothing can stop it from growing effectively, which means that rebars in a concrete pavement does not help anything. New York BC Thank you. I have to disagree that deformed bars do not help anything regarding cracking in a pavement. Even if it keeps a crack tightly together to maintain aggregate interlock, it’s done something. KWM I would refer you to the AASHTO Guide on the Design of Pavements. In particular, the section on continuously reinforced concrete pavements. Steel in this design does not prevent cracking , but instead hold the crack tightly together. 13. Can Kevin comment on if Neenah is marketing their telescoping manholes? Minnesota KWM The Wisconsin Concrete Pavement has for quite some time been encouraging Neehah, WI based Neenah Foundries to complete and implement their new designs on telescoping manholes. Please join me in reinforcing to them that this product is needed and would benefit the performance of concrete pavements. 14. How soon after the concrete is placed should the contractor saw the concrete? North Carolina BC That’s a big “it depends.” Depends on the mix, the weather, and the equipment. Early entry saws can cut sooner that wet cuts. Old timers will scratch the concrete with a nail and when it’s sufficiently white, they cut. Some states use Hiperpave to identify the saw cut window. In the cooler weather, you have more time than warmer weather. KWM Timing of sawing is one of the true arts of concrete pavements. Temperature of concrete, ambient temperature, sun exposure, time of placement, cementitious material types and content are all part of the art of determining when it is time to start sawing. Then you introduce the type of saw and adjust your timing to meet the ability and weight of the equipment. Begin sawing when the saw produces no or an acceptable amount of raveling of the joint, but sooner than the time in which cracking would start. 15. Bill, what are you sealing your joints with in New York? Nevada BC I think that’s covered in 4, 6, and 7 above. Nevada is going to be different from New York. 16. What is meant by "High Performance" dowel bars? Nevada KWM Dowels bar designed to perform for the performance life of the high performance concrete pavement in which it has been installed. In Wisconsin and several other states, these are pavements that have been designed for 50 years of traffic and performance. So, in simple terms they are dowels that have higher scrutiny in testing to show that they have corrosion resistance for 50 years and can provide load transfer for 50 years. As you saw in my slides all of the alternatives given were corrosion resistant materials. 17. Need to mention when sawing, sometimes the contractor does not cut all the way through side of pavement, sometimes due to metal forms. But, once forms are moved and crack has not form, they should go back and saw edges. I also, make a point to tell my inspectors to go through to visualize a crack under the saw, quick way to identify if contractor is sawing at proper depth. Missouri BC Agree 100%. We allow demo saws for that touch up. KWM Agree with your concern. We have seen a higher frequency of spalling and joint distress when they are not sawed through the edge. 18. Do you recommend using transfer dowel bars in circular concrete truck aprons within roundabouts? Indiana BC Each truck apron should be designed on its own merits. How many trucks and what axle configurations can provide insights. For our roundabouts, I would say it’s 50-50, but we don’t have a roundabout that I feel requires dowels in the entire radial joint of the truck apron. We typically have 2 “lanes” in our aprons (1 longitudinal joint) and I would only do the outer “lane,” if at all. KWM Agree with Bill, each truck apron should be designed on its merit for requiring dowels. To date all of them built in Wisconsin have been built with dowels in the traffic lanes, but not necessarily in the truck apron. We have seen cracking in roundabouts that I can contribute to too much steel and the geometry of the slab challenges that we can have in roundabouts. 19. In intersection joint layout where two adjacent slabs are intended to remain unbonded due to different directions of movement, is it recommended to place a "sleeper slab" (unbonded) under the pavement slabs to prevent joint faulting? Indiana BC I hate sleeper slabs. Just my opinion. We used to use sleeper slabs at structural approach slab/pavement interfaces under the pressure relief joint. Here are my thoughts in no particular order. It seems like we get more cracking in concrete on sleeper slabs. I like good compaction and consistent support. I see no reason we can’t get good compaction in any intersection we’ve ever done. And if the cross street is asphalt, we wouldn’t consider a sleeper slab. Generally, I’d have to say the truck traffic and speed of traffic do not warrant a sleeper slab in an intersection. I do like to make any first slab off of a free edge go down to our “Lmin.” Especially where we abut HMA. HMA will hump adjacent to PCC and making that first slab as stout (less slender) as possible will increase loads to failure. I think Lmin is also preferable to a thickened edge. I really like consistency in a cross section. You make that first slab 10’ long instead of 15’ and it’ll take more to crack it. The sleeper slab can present a compaction problem itself. They cost money and take time. KWM Interesting question. The only sleeper slabs we build is in the concrete pavement approach slabs for bridges. We have done this since 2014. We want the joint to handle the majority of the expansion. We have seen improved performance of the approach slabs with this policy. I know of no engineering document from FHWA or ACPA that promotes the use of a sleeper slab in the application you mention. Everything in the ACPA jointing documents IS006 and TB019 is traditional jointing practices with a predominant roadway given the ability to expands and contract and the “side road” accommodating expansion with the proper use of these joints at the intersection radiuses. Joints Webinar – Questions and Answers | |
| Achieving Smoothness in Concrete Pavement Construction (RTS) | 👤 Gary Fick 👤 Sarah Sanders 👤 David Howard | Concrete Pavement Technology Tuesday Webinar | 2020 |
| 2020-07-21 | Achieving Smoothness 1 Smooth Pavements Are What the Customers Want 2 The customer doesn’t want the road infringing upon their driving/riding experience… 3 or their cargo! 4 Expectations are changing with regards to how we spend our time in vehicles. 5 Expectations for productivity while on the road may be changing too… 6 Autonomous or self-driving vehicles are here. 7 The customer will get his or her way… 8 even when they are wrong! 9 Satisfying the customer with our products requires collaboration, planning, and execution. • What the customer wants is simple: pavements that do not detract from their experience in vehicles while driving on the pavement. • To deliver this requires a collaborative effort: • Policy decision makers need to understand what the customer wants. • Designers need to foresee the impediments to delivering on what the customer wants. • Contractors need to close the deal during construction! 10 Question One: What is Smooth? 11 This is smooth! 12 Question One: What is smooth pavement to the customer? Answer: Pavement that rides uniformly smoothly, quietly, and has little impact on the travel of the vehicle. 13 Engineers can define smooth, but… 14 Those pesky customers will tell us what they want if we listen. 15 16 17 18 Question Two: Are policy decision- makers, designers, and contractors ALL needed to build smooth pavements? 19 YES! 20 21 22 Designers – Don’t expect a silk purse to be made from a sow’s ear! • If the customers’ “riding” experience is not considered throughout much of the design process, it can detract from satisfying the customers. • We can, of course, make a silk purse from a sow’s ear if we use all of the tools available to us and know what the customer wants. 23 24 25 26 27 28 29 Policy Decision-Makers: Customers want uniformity of smoothness and uniformity of tire- pavement noise. • Diamond Grinding is a tool that can be used for more than meeting a specified smoothness… don’t be afraid to use it continuously on certain projects! 30 Question Three: What are the biggest cchallenges to the paving contractor to deliver smooth pavements? 31 Answer: Not stepping back often enough and asking, what does the customer need for this project to be smooth? 32 33 34 35 Thank you! 36 | |
| 4. Concrete Pavement Management and Preservation Performance Resources | 👤 Michael Darter | Concrete Pavement Technology Tuesday Webinar PAVEMENT PRESERVATION WEBINAR SERIES | 2020 |
| 2020-06-23 | The Concrete Pavement Preservation Series IV Concrete Pavement Management and Preservation Resources TECHNOLOGY TRANSFER How to Construct Durable Full-Depth Repairs in Concrete Pavements How to Construct Durable Partial-Depth Repairs in Concrete Pavements Proper Diamond Grinding Techniques for Pavement Preservation Proper Construction Techniques for Dowel Bar Retrofit and Cross-Stitching Proper Joint Sealing Techniques for Pavement Preservation Missouri DOT Website Upcoming Webinar Schedule – Technology Tuesday July 21 Achieving Smoothness in Concrete Pavement Construction August 18 Concrete Pavement Joint Design, Layout and Construction September 22 Resiliency/Resilient Pavement Systems The Webinar Series is offering Professional Development Hours (PDH’s) We offer webinar sign up for all our programs at https://go.acpa.org/cp-tech-center-2020 REGISTER FOR ALL UPCOMING WEBINARS FROM ONE LINK Super Easy to Participate Please Register for Upcoming Webinars at https://go.acpa.org/cp-tech-center-2020 Michael Darter, PE PhD, Repair/Preservation of Concrete Pavements Questions? www.cptechcenter.org The Concrete Pavement Preservation Series IV Concrete Pavement Management and Preservation Resources Concrete Pavement Repair/Preservation Best Practices & Performance Michael I. Darter, PE, PhD Applied Research Associates, Inc. Study Conducted for Missouri DOT/FHWA 23 June 2020 CP Tech Center Webinar Overview • A National Survey was conducted to gauge the experiences of State DOTs & Contractors with several concrete pavement repair/preservation techniques, with emphasis on design, specifications, construction practices, inspection/acceptance, & performance. • State DOTs that are leaders in best practices for six repair/preservation techniques were selected. • Questionnaires & Interviews of 15 expert State & Contractor personnel in 7 States were completed. State & Contractor Survey State Personnel • UT: Jason Simmons, UDOT • MO: John Donahue, MoDOT • WA: Jeff Uhlmeyer, WSDOT • MN: Gordon Bruhn, MnDOT • CA: Linus Motumah, CalTrans • GA: Wouter Gulden, Ret. GDOT • KS: Rick Barezinsky, KDOT Contractor Personnel • UT: Ken Passey, A-Core Conc. Cutting, Inc. • MO: Terry Kraemer, Diamond Service, Inc. • WA: Robert Seghetti, ACME Concrete Paving, Inc. • MN: Matt Zeller, Minnesota Concrete Pavement Association • MN: Terry Kraemer, Diamond Services, Inc. • CA: Casey Holloway, Penhall Company • GA: John Depman, Penhall Company • KS: Robert Kennedy, Koss Construction Company Repair/Preservation Techniques 1. Full-depth Repair (FDR) & Slab Replacement 2. Partial-depth Repair (PDR) 3. Dowel Bar Retrofit (DBR) 4. Diamond Grinding (DG) 5. Cross Stitching (CS) 6. Slab Stabilization (SS) Missouri DOT Website https://spexternal.modot.mo.gov/sites/cm/CORDT/ 1. Report: “Concrete Repair Best Practices: A Series of Case Studies” 2017 2. “6 Tech Briefs” 3. “6 Training Presentations” Sponsored by: MoDOT & FHWA Conducted by: Applied Research Associates, Inc. Missouri DOT Website https://spexternal.modot.mo.gov/sites/cm/CORDT/ Full-Depth Repair (FDR) & Slab Replacement FHWA, 1998 Full-Depth Repair Key Factors California (JPCP), Missouri (JRCP), and the other States have developed and refined FDR techniques and specifications that have produced 15+ year service lives: • Appropriate FDR conditions • State FDR load transfer design • Length/width of FDR • Repair of base area • Anchoring dowel bars • Opening to traffic • Inspection/Acceptance • Performance State FDR Load Transfer Design State Slab Thick (in) Dowel Location Dowels At Joint Dowel Dia-meter (in) CA =<9 WP 4+4 @ 12 in 1.25 GA =<10 Uniform 11 @ 16 in 1.25 MO All WP 5+5@ 12 in 1.00 MN All Uniform *11 @ 12 in 1.25 CA >9 WP 4+4 @ 12 in 1.5 UT All WP 4+4@ 12 in 1.5 WA All Uniform 11@ 12 in 1.5 GA >10 Uniform 11 @ 16 in 1.5 *Needed due to variability in anchoring dowels Dowel Diameter • The dowel bar diameter is the most critical design factor, since a slight change in diameter (e.g., ¼ inch) dramatically affects the steel/concrete bearing stress under a wheel load. • Loosening of the dowel bar reduces joint LTE and increases base erosion, faulting, and roughness. • Field tests have clearly shown that larger diameter bars show less transverse joint faulting. I-80 Extended AASHTO Road Test Joint Faulting & Cracking, 1958-1975 Joint Faulting Fatigue Crack & Faulting I-80 Extended AASHTO Road Test JPCP/Gran. (1958-1975) 0 0.05 0.1 0.15 0.2 0.25 0.3 1.00-in 1.25-in 1.375-in 1.625-in Jo in t Fa u lt in g, in Dowel Diameter, in 8-in 9.5-in 11-in 12.5-in Dowels spaced @ 12 inches across lane Layout of Dowels Across Joints Most truck wheels nearer edge of slab makes it desirable to focus dowels near edge and in wheel paths. (Source: Caltrans) FDR Anchoring Dowels [Key Issue] • Anchoring of the dowel bars permanently into the existing slab is the most critical FDR placement step. • If not done properly, the dowels will eventually become loose, the FDR joint will lose joint LTE, and pumping and faulting will develop. FDR Anchoring Dowels [Key Issue] • Most State specifications require: – Drilling holes for dowel + annular gap – Clean with air – Inject epoxy resin or grout into the hole – Rotate the bar during insertion – Use grout retention rings – Place end caps on protruding dowels – Coat bars with lubricant Anchoring Dowel Bar Into Slab (FHWA/NHI 1998) Sawcut Through Existing Joint Showing Lack of Anchoring Material Around Dowelbar: No Grout Retention Ring (photo courtesy Dr. Mark B. Snyder) Sawcut Through Existing Joint Showing Good Surrounding Anchoring Material Around Dowelbars: Grout Retention Ring (photo courtesy Dr. Mark B. Snyder) Full-Depth Repair Performance • Performance of FDR in California, Missouri, Georgia, Minnesota, Utah, and Washington has been overall good (with some exceptions). – Service life ranging from 10 to 20+ years for JPCP and JRCP. • California: Surveys of Rapid Strength Concrete (RSC) slab replacement projects at 3 & at 13- years showed promising results. California Highway I-10 EB (PM 15-30) Near San Bernardino showing two 14-year old RSC slabs outer Lane #4. Rapid Strength Concrete (RSC) is made with hydraulic cement that develops minimum opening age and 7-day modulus of rupture: • Night placement: 11-pm closing & 5-am opening. • Mod. Rupture Str. > 400-psi before opening traffic & >600-psi 7-days. • Materials: 4x4 MB; CTS Surveys of RSC projects at 3 & 13-years showed: • Very low amounts of joint spalling, shrinkage cracking, longitudinal cracks, and corner cracks. • Transverse fatigue top down cracking in heavy truck lanes was the only significant development in 13-years. RSC Slab RSC Slab Original 8-in slab Original 8-in slab Performance Rapid Strength Concrete (RSC) --- 8-9 inch Independent Slab Replacement (CA) 0.34% 0% 0.1% 0.8%0.8% 0.3% 0.3% 8.8% 0 1 2 3 4 5 6 7 8 9 10 Joint Spalling Longitudinal Cracks Corner Cracks Transverse Cracks P er ce n t R SC S la b s Distress Type RSC Slabs Performance At 3 & 13 Years 13-Years3-Years Caltrans Random Vs Continuous RSC Pavement Design Caltrans 41-9: Individual RSC Slab Replacement Caltrans 40-5: Continuous RSC Slab Replacement Slab Thickness Same as Existing (8-9 in) Thicker 10-12 in Base Course LCB or CTB New LCB Joint Spacing Existing JPCP 12, 13, 18, 19-ft 14-ft/Dowels RSC 2003 11.4-in 14-ft Jt Space PCC 1980 9-in 12-19 ft Jt Space Dowel Bar Retrofit Dowel Bar Retrofit Key Factors Washington and the other States have developed and refined DBR techniques and specifications that have produced long service lives for JPCP and JRCP projects. • Appropriate conditions for DBR. • Effectiveness of the DBR design/layout. • DBR slot material. • Inspection/acceptance of DBR. • Performance of DBR Appropriate DBR Conditions • If existing mean joint faulting is > 0.125 inches (causing high IRI) it is highly likely that faulting will develop similarly after diamond grinding if no DBR. • The AASHTOWare Pavement ME Design software can be used to estimate future faulting & cracking w/ and w/o DBR. AASHTOWare Pavement ME Design Faulting Prediction for a JPCP Grinding Project Missouri DBR of Transverse Crack JRCP (10 yrs) DBR prevents breakdown & faulting of transverse crack Washington DBR Layout/Design To avoid cracks here State DBR Designs State No. Bars / Wheelpath Bar Diameter, inch Washington 3 1.50 Utah 3 1.50 California (>9 in) 3 1.50 California (<9 in) 3 1.25 Missouri 3 1.25 Minnesota 3 1.25 Projects in California and Minnesota have shown an increase in transverse joint LTE from 30 or less to over 80 percent after DBE, which indicates why very little faulting has developed. Retrofit Dowel Bar Specifications Placing Assembled DBR Into Slot Retrofit Dowel Bar Slot Material • Washington uses prepackaged mortar extended with aggregate (example product: CTS non-shrink rapid set grout). • These materials have provided good performance in Washington. The slot material is placed, consolidated, and cured until ready to open to traffic. • California uses polyester concrete consisting of polyester resin binder and dry aggregate. The existing slot surface is treated with high molecular weight methacrylate bond agent. Inspection/Acceptance of DBR • Washington has a detailed inspection plan in their construction manual that includes meeting with the contractor, visual confirmation of slots, sandblasting faces clean, aligning dowels properly, ensuring foam core inserts are vertical to form the joint, consolidating fill material, and working equipment to accomplish these tasks. • Contractors in Washington believe that inspection of the slot is extremely important. Sandblasting is believed to be the only way to get it clean (water blasting does not appear to work as well as sand blasting which aids bonding). Performance of DBR Washington • Overall, DBR performance has been good with very few performance issues. If constructed as part of CPR and done earlier in the JPCP life, the future pavement life can be extended 20 to 30 years. California • DBR projects have performed well in California, with typical service life between 10 and 15 years. DBR joints have been tested using the FWD for LTE > 80%, which is an effective criterion for good performance. WSDOT DBR/Grinding Survival Data (Add 3 years to these lives) Diamond Grinding Diamond Grinding All of these States have outstanding diamond grinding specifications and performance: 1. Significant roughness reduction. 2. Good frictional & textured surfaces. 3. Significant noise reduction. 4. Multiple grinding applications with pavement life extensions until next CPR, OL, or reconstruction. Impact of Diamond Grinding On Smoothness (20-50-80% IRI Reduction) 0 50 100 150 200 250 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 IR I( in /m i) Year After DBR & DG Before DBR & DG Texas DOT Diamond Grinding: Project Selection • Proper design & construction of all CPR repairs must be accomplished without causing problems to grinding, e.g., slab jacking, & lots of elastomeric “soft” or “melt-able” patches that cannot be ground and damages grinding equipment. Diamond Grinding: Incentives • Incentives/disincentives are used by a number of States for grinding smoothness. The incentive has to be enough to make it worthwhile to the contractor to increase their effort to achieve a smoother surface. • Smoother pavement = longer life! • Knowing they can acquire a bonus allows experienced contractors to lower their diamond grinding unit bid price by an amount equivalent to the bonus. Utah Diamond Grinding Survival (58 Projects 1988-2015) • 91% of Diamond Grinding projects still in service (up to 17-years in service to 2015). • 100% Diamond Grinding projects that included DBR are still in service with good performance. • Preservation/Repair significantly helped extend the life before a Structural Overlay or Reconstruction was required. 0 10 20 30 40 50 60 70 80 90 100 0 to 4 5 to 9 10 to 14 15 to 20 Su rv iv al , % DG Age, Years Utah DG Survival 2015 Utah Diamond Grind/DBR Life Extension DBR Utah I-15 NB (1984 Construction, 2007 DG/DBR) Diamond Grinding: Project Selection • Multiple diamond grindings (2 to 4 times) on projects over the years (reduction in slab thickness) has not shown much evidence of an increase in structural fatigue cracking. – Use AASHTO ME “Restoration” to check future fatigue cracking in particular for reduced thickness, as well as faulting, and IRI. San Bernardino Freeway, CA 8-in/3-in AC, Non-Doweled, JPCP (I-10 Outer 2-Lanes) Constructed/Diamond Ground Construction 1947 (Route 66) DG 1967 (1st DG in USA) DG 1983-85 DG 1998-2000 DG 2012-2015 (parts of I-10) In-Service Years New 20 17 15 15 1947-2018 1947-2018 Cross-Stitching Cross-Stitching Key Factors Kansas and the other States have developed and refined cross-stitching techniques and specifications that have contributed to long service lives for JPCP and JRCP projects. • Appropriate conditions for Cross-Stitching. • Effectiveness of the Cross-Stitching bar design/layout. • Drilling holes & anchoring tie-bar material. • Inspection/acceptance of Cross-stitching. • Performance of Cross-Stitching Appropriate Conditions Cross-Stitching • Cross-stitching is a technique applied to an existing concrete pavement, can be new or older, to longitudinal cracks and joints to keep tight. • Cross-stitching has been performed on slabs typically 7 inches or thicker successfully. One contractor reported that cross-stitching performed on a 5-inch concrete slab also worked out well. Cross-Stitching: Key Points • High percentage of longitudinal cracks and joints will open up over time if not “reinforced” creating serious problems. Photo of Longitudinal Crack w/Cross- Stitched Tiebar, 10 years (MO) Design Aspects Cross-Stitching • Criteria of existing joint or crack: • Contractors have successfully cross-stitched cracks/joints up to 1 inch wide, and they have performed well. The technique has not worked well on cracks/joints wider than 1 inch, and it should not be done. • Kansas hole layout, alternating sides – Longitudinal Joints: 30-inch spacing, 0.75 in rebar (0.15 percent area steel, 10-inch slab) – Longitudinal Cracks: 24-inch spacing, 0.75 in rebar (0.18 percent area steel, 10-inch slab) Kansas: Drilled Hole Detail Performance: Cross-Stitching • Kansas: Cross-stitching of longitudinal cracks and joints has maintained crack width over time, and no spalling has occurred. The 2002 East Topeka Interchange project with over 30 miles of cross-stitching of the longitudinal joint is still performing well, and the longitudinal joint is tight (15y). • Missouri: The oldest cross-stitching projects are 10 years old. These projects exhibit only a few locations of spalling of the longitudinal cracks. These projects on I-70 and elsewhere were under very heavy truck traffic, and some cracks were in the wheel paths. • Minnesota: Longitudinal cracks have maintained crack width over time. One project in Minnesota was a 5- to 6- inch thin portland cement concrete overlay with longitudinal cracks. The project is now nearly 10 years old, and longitudinal cracks are still in good condition. Overall, a 20+ year service life is estimated. Partial Depth Repair (PDR) FHWA 1998 Partial Depth Repair(PDR): Key Points Keys To Long Life PDR (Highest Risk Treatment) 1. The first key is to limit usage to the appropriate joint and crack locations and conditions. Minnesota, Washington, California, Missouri, Georgia, and Utah use PDR for spall repair of transverse and longitudinal joints where there is sound concrete in the bottom half of the slab. 2. The second key is the detail and effectiveness of the specifications, special provisions, and standard drawings (design) for PDR. Minnesota (lead State) and the other States provide significant design and specification detail for PDR including field boundaries, removal of concrete, forming of joints, inspection/acceptance, and curing. Partial Depth Repair(PDR): Key Points Keys To Long Life PDR 3. The third key is the repair material, where conventional and proprietary rapid setting cementitious mixtures are extensively used. 4. The fourth key is the inspection/acceptance procedures and their effectiveness. Warranties (e.g., 30 days) appear to be an effective approach. Performance of PDR • Overall the performance of PDR shows that this technique has been highly variable, both within and between States. • If properly installed using the procedures established in Minnesota and the other States surveyed, and placed by knowledgeable contractors with effective inspection, and a 30-day warrantee: – PDR typically lasts 10 to 15 years or more. – However, if things are not done properly, the PDR ends up with a short life of < 5 years. • For example, if a PDR is placed in a situation where there is surrounding concrete deterioration, slab has underlying deterioration > ½ thickness, then it will not last long. A full- depth repair would have been a much more effective repair for these situations. Slab Stabilization Ron Youngman, CST Slab Stabilization Key Factors • Slab stabilization is defined in Missouri & Georgia as the restoration of full support at slab joints/cracks, locations where deflection testing indicates loss of support. • Key factors include locating slab corners with loss of support, appropriate drilling of holes, injecting non-erodible material into the holes that do not lift slab significantly but fill in voids below, and finally testing to assure full support to the slab. FWD Load/Deflection Testing At Slab Corners Verifies Loss of Support Missouri Uses FWD Load Vs Deflection: Loss of Support at Corners 1993 AASHTO Guide, Part III, Chapter 3, Section 3.5. After Stabilizing (Full support) Before Stabilizing (Large Void) Slab Stabilization Material • Material that is injected beneath slabs/stabilized base is critical to erosion & pumping. • Lots of cement grout and asphalt used in past. These have been largely successful. • Today, polyurethane material is most used successfully to restore support and this material may also have some ability to reduce future erosion and pumping and improve joint LTE if properly placed. Performance Slab Stabilization • Missouri. The typical service life of slab stabilized jointed reinforced concrete pavement (mostly at working transverse cracks) in Missouri was estimated by experienced staff of the State at 5-10 years. • A contractor who has conducted many concrete pavement restoration projects estimates life of slab stabilization using polyurethane injection material as 10-15 years. Summary Repair/Preservation Performance Final point: What is the overall impact of the combined repair/preservation treatments on the performance & survival of JPCP? – Everyone that I interviewed believed that collectively these treatments have a very significant impact on the survival and service life of JPCP before major rehabilitation was required (e.g. overlay, reconstruction) – Lets look at the Data: Washington & Utah WSDOT DBR Survival Data (Add 3 years to these lives) International Grooving and Grinding Association Utah Survival Results: OL & RECON (1964-2015: 108 JPCP) Survival Data Summary JPCP JPCP Age Years Total Sections OL & RECON Sections* SURVIVAL % Sections 0 to 9 27 0 100 10 to 19 18 2 89 20 to 29 31 1 97 30 to 39 19 8 58 40 to 51 13 6 54 Totals 108 17 -- * 51% had received repair/preservation treatments (CPR) Utah Survival Results (1964-2015: 108 JPCP) Utah Survival Results • Mean life (until major rehab of overlays or reconstruction) of 108 JPCP projects since 1964 was 40 to 51-years. (Design life = 20-yrs) • Major distress types: – Transverse joint faulting (no dowels in older projects) – Some longitudinal cracking & transverse (fatigue) cracking – Some joint spalling from low air content, etc. • How was this long life achieved? 51% of these JPCP received repair/preservation treatments: slab replacement, partial-depth repair, dowel bar retrofit, & diamond grinding. Mean Life Extension = Total Life / Original JPCP Life = 1.8 Utah I-215E SLC (1988 Construction, 2005 DG/DBR) Missouri DOT Website https://spexternal.modot.mo.gov/sites/cm/CORDT/ • Tech Report, Tech Briefs, & Training Presentations available on Missouri DOT website. [Thanks to MoDOT & FHWA funding] • Repair & Preservation techniques applied before reaching “poor” conditions can increase the life of JPCP by about double the non- preserved life!Concrete Pavement Preservation Webinar 4 – Questions and Answers The questions submitted during the webinar follow with answers that our speakers have provided. Additional resources are available at https://cptechcenter.org/pavement-preservation/ and https://spexternal.modot.mo.gov/sites/cm/CORDT/ Do you generally recommend retrofit of 100% of joints on projects? Recommend you consider DBR by traffic lane and truck volume. Get the traffic data on truck lane distribution and that will give a good idea where you need dowels. Certainly, any lane that has substantial truck traffic will fault if no DBR. Inner and HOV lanes typically do not need DBR. Also, another alternative, look at the joint faulting on each lane (use IRI if needed). Consider using Washington’s criteria of mean faulting of 20 joints < 0.125 inches may not need DBR. Do you recommend sealing or not sealing JPCP? Guidance on joint sealing is also available from http://www.acpa.org/wp-content/uploads/2019/04/Jointing-Sealing-Tech-Bulletin-TB010-2018.pdf Is there a specific type of grease to use on the bars? The recommendation in the following publication is to use plant based material, typically tectyl, or an asphalt based coating. https://intrans.iastate.edu/app/uploads/2018/08/Dowel-load-guide.pdf Under the white topping, the HMA is stripped and damaged. For a full depth repair, is it a good idea to remove the damaged HMA and use flowable fill before placing the concrete? A challenging question! Its especially interesting to see that the HMA has stripped and is damaged. Seems like there are these alternatives: (1) Remove the PCC slab area and the deteriorated HMA and then just place fresh concrete into the repair area. This would give you a good bond/friction between the good HMA and the new slab. (2) Remove the PCC slab and deteriorated HMA and place new HMA if you can compact it well. (3) Remove the PCC slab and deteriorated HMA and replace that with flowable fill. The best alternative may be to replace the deteriorated HMA with new HMA material that has been checked for stripping and hydrated lime used if so. This would keep a uniform layer upon which the PCC slab resides, that may avoid other problems in future. What alignment of dowel bar is recommended with respect to traffic direction? Dowel bars should be parallel to direction of mainline pavement traffic. ACPA is developing guidance on tolerance w.r.t. vertical skew, horizontal skew and depth. Some states do have tolerances, but to date there is no universal standard. What is the maximum % of slab thickness for grinding? I would not specify that as a % of slab thickness but base it on the existing slab thickness. If the slab is relatively thin (<24 cm), then I would not want to lose more than 2.5 cm say. If the slab is relatively thick (>24 cm), then you could loose more than say 5 cm. But if your slab is =>25 cm I would not worry much about thickness and remove what was needed to smooth out the pavement. Why do you suppose WA has had excellent performance of DBR? Can it be attributed to timing of DBR, expertise of contractors, or anything else? They have sound concrete for sure with little transverse joint spalling. They have conducted lots of research on DBR also. Dr. Linda Pierce did her excellent PhD thesis on this topic and fed that right into the procedures. All this helped Washington develop some effective specs and guidelines and inspections. Why would distance from the longitudinal joint vary for DBR and full depth plain concrete replacement? For DBR Mr Darter stated Washington DOT found extra stresses within first 18in and therefore DBR uses 18in spacing, but for plain everyone still uses 12in or less for dowel placement. Very good question! I have seen the cracking that Washington experienced and its basically a corner break or crack that goes right through the DBR slot. Here is the key reference: Pierce, L.M., Uhlmeyer, J.S and Weston, J. “Dowel Bar Retrofit – Do’s and Don’ts,” Report WA-RD 576.2, Washington DOT, March 2009. [bookmark: _GoBack] | |
| 3. Concrete Pavement Preservation Treatment Construction (with Case Studies Case Study) | 👤 John Roberts 👤 Randy Everett | Concrete Pavement Technology Tuesday Webinar PAVEMENT PRESERVATION WEBINAR SERIES | 2020 |
| 2020-06-16 | The Concrete Pavement Preservation Series III Concrete Pavement Preservation Treatment Construction The CP Tech Center TECHNOLOGY TRANSFER Upcoming Webinar Schedule – Technology Tuesday June 23 Concrete Pavement Preservation IV Concrete Pavement Management and Preservation performance and resources Registration is now open for these upcoming webinars July 21 Achieving Smoothness in Concrete Pavement Construction August 18 Concrete Pavement Joint Design, Layout and Construction The Webinar Series is offering Professional Development Hours (PDH’s) We offer webinar sign up for all our programs at https://go.acpa.org/cp-tech-center-2020 REGISTER FOR ALL UPCOMING WEBINARS FROM ONE LINK Super Easy to Participate Please Register for Upcoming Webinars at https://go.acpa.org/cp-tech-center-2020 John Roberts Randy Everett Questions? www.cptechcenter.org The Concrete Pavement Preservation Series III Concrete Pavement Preservation Treatment Construction Concrete Pavement Preservation Treatment Construction Keeping good roads in Good Condition! 0.75-in. dia. Rebar Epoxy into Place Note A: Distance between holes is 24 in. for heavy traffic; 36 in. for light traffic Note B: Determine distance from longitudinal crack to hole based on slab thickness T and drill angle. Slabs less than 12 inches thick require a 35° insertion angle. Centerline END VIEW SIDE VIEW 0.125 0.125 (3.2 mm ) Core Segment ! I - 635 WB Lanes K1, K2 K3 & K4 152 61 Av er ag e IR I Before Grinding 698 Bumps After Grinding 29 Bumps STATE OF CALIFORNIA DEPARTMENT of TRANSPORTATION DIVISION OF ENGINEERING SERVICES MATERIALS ENGINEERING AND TESTING SERVICES OFFICE OF RIGID PAVEMENT AND STRUCTURAL CONCRETE 5900 Folsom Boulevard Sacramento, California 95819 THE EFFECTIVENESS OF DIAMOND GRINDING CONCRETE PAVEMENTS IN CALIFORNIA November 2004 STATE OF CALIFORNIA DEPARTMENT of TRANSPORTATION DIVISION OF ENGINEERING SERVICES MATERIALS ENGINEERING AND TESTING SERVICES OFFICE OF RIGID PAVEMENT AND STRUCTURAL CONCRETE 5900 Folsom Boulevard Sacramento, California 95819 THE EFFECTIVENESS OF DIAMOND GRINDING CONCRETE PAVEMENTS IN CALIFORNIA November 2004 Reservoir Backer Rod Sealant Nozzle Unsealed vs Sealed Joint is about 5 dBA International Grooving and Grinding Association at www.igga.net Concrete Pavement Preservation Phoenix Diamond Grind Story Presentation By: Randy Everett Sr. Division Administrator Date: June 16, 2020 CENTRAL DISTRICT MAP Who We Are? • 160 Maintenance Personnel 15 District Units • 90 Construction Personnel 9 District Units What We Do? • 435 (5,500 lane miles) Miles of Roadway & Bridge Maintenance • 258 Miles of Landscape Maintenance • $500M Yearly Construction Budget (not including South Mountain) • 20-25 Projects Occurring Per Year 3 Types of Projects • Preservation • Modernization • Expansion 2003 Solution to Noise Reduction • Problem: Concrete (PCC) was originally transversally tined – Very Loud • Solution: Apply 1” Asphaltic Rubber friction Course (AR-ACFC) atop all PCC surfaces to reduce noise Beautiful New Overlays How Do We Preserve Our Freeways? Aging Conditions Cost Big $ We Have a Whole Lot of This 53% Good 53%46% 1% Good Fair Poor 72% 69% 73% 69% 61% 63% 64% 54% 53% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 2010 2011 2012 2013 2014 2015 2016 2017 2018 Pavement Condition: Interstates 35% Good 68% 67% 68% 63% 56% 54% 53% 41% 35% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 2010 2011 2012 2013 2014 2015 2016 2078 2018 Pavement Condition: NHS 35% 62% 4% Good Fair Poor 23% GoodPavement Condition: Non-NHS 44% 43% 43% 41% 36% 36% 35% 27% 23% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 2010 2011 2012 2013 2014 2015 2016 2017 2018 23% 71% 6% Good Fair Poor 78 75 75 69 64 63 65 65 59 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 2010 2011 2012 2013 2014 2015 2016 2017 2018 NHS Bridge Condition 59% 40% 1% Good Fair Poor 59% Good Keep the Good Good • Crack Seal • Flush • Pot Hole Repair (Delamination of 1” Asphalt Surface) Pavement Preservation - Flush New Asphalt Overlay Options Are Needed • What if we went back to a PCC Surface? • What if we could make the underlying PCC Pavement Surface better? • Would it/Could it last a lot longer with little need for maintenance or replacement? What if: Instead of? Tears Into the Concrete Damaged Joints from Typical Milling Kyrene Road Ramp Area Experiment (April 6, 2019) Distressed Rubberized Asphalt Rideable Surface in Good Condition SR101 EB Test Section (April 27, 2019) • 4 Test Sections • Diamond Grind, Next Gen, Skid Abrader & Micro-Mill • Ride, Sound, Appearance • What does the public think? SR101 EB Test Section (April 27, 2019) Diamond Grind SR101 EB Test Section (April 27, 2019) Next Generation SR101 EB Test Section (April 27, 2019) Skid Abrader SR101 EB Test Section (April 27, 2019) Micro-Mill SR 202 Diamond Grind Real Life Project (May 11, 2019) Loader to Remove Rubber Asphalt Small Diamond Grinders Finished Condition The Concrete Pavement Preservation Series III Concrete Pavement Preservation Treatment Construction The CP Tech Center TECHNOLOGY TRANSFER Upcoming Webinar Schedule – Technology Tuesday June 23 Concrete Pavement Preservation IV Concrete Pavement Management and Preservation performance and resources Registration is now open for these upcoming webinars July 21 Achieving Smoothness in Concrete Pavement Construction August 18 Concrete Pavement Joint Design, Layout and Construction The Webinar Series is offering Professional Development Hours (PDH’s) We offer webinar sign up for all our programs at https://go.acpa.org/cp-tech-center-2020 REGISTER FOR ALL UPCOMING WEBINARS FROM ONE LINK Super Easy to Participate Please Register for Upcoming Webinars at https://go.acpa.org/cp-tech-center-2020 John Roberts Randy Everett Questions? www.cptechcenter.org The Concrete Pavement Preservation Series III Concrete Pavement Preservation Treatment Construction Concrete Pavement Preservation Treatment Construction Keeping good roads in Good Condition! 0.75-in. dia. Rebar Epoxy into Place Note A: Distance between holes is 24 in. for heavy traffic; 36 in. for light traffic Note B: Determine distance from longitudinal crack to hole based on slab thickness T and drill angle. Slabs less than 12 inches thick require a 35° insertion angle. Centerline END VIEW SIDE VIEW 0.125 0.125 (3.2 mm ) Core Segment ! I - 635 WB Lanes K1, K2 K3 & K4 152 61 Av er ag e IR I Before Grinding 698 Bumps After Grinding 29 Bumps STATE OF CALIFORNIA DEPARTMENT of TRANSPORTATION DIVISION OF ENGINEERING SERVICES MATERIALS ENGINEERING AND TESTING SERVICES OFFICE OF RIGID PAVEMENT AND STRUCTURAL CONCRETE 5900 Folsom Boulevard Sacramento, California 95819 THE EFFECTIVENESS OF DIAMOND GRINDING CONCRETE PAVEMENTS IN CALIFORNIA November 2004 STATE OF CALIFORNIA DEPARTMENT of TRANSPORTATION DIVISION OF ENGINEERING SERVICES MATERIALS ENGINEERING AND TESTING SERVICES OFFICE OF RIGID PAVEMENT AND STRUCTURAL CONCRETE 5900 Folsom Boulevard Sacramento, California 95819 THE EFFECTIVENESS OF DIAMOND GRINDING CONCRETE PAVEMENTS IN CALIFORNIA November 2004 Reservoir Backer Rod Sealant Nozzle Unsealed vs Sealed Joint is about 5 dBA International Grooving and Grinding Association at www.igga.net Concrete Pavement Preservation Phoenix Diamond Grind Story Presentation By: Randy Everett Sr. Division Administrator Date: June 16, 2020 CENTRAL DISTRICT MAP Who We Are? • 160 Maintenance Personnel 15 District Units • 90 Construction Personnel 9 District Units What We Do? • 435 (5,500 lane miles) Miles of Roadway & Bridge Maintenance • 258 Miles of Landscape Maintenance • $500M Yearly Construction Budget (not including South Mountain) • 20-25 Projects Occurring Per Year 3 Types of Projects • Preservation • Modernization • Expansion 2003 Solution to Noise Reduction • Problem: Concrete (PCC) was originally transversally tined – Very Loud • Solution: Apply 1” Asphaltic Rubber friction Course (AR-ACFC) atop all PCC surfaces to reduce noise Beautiful New Overlays How Do We Preserve Our Freeways? Aging Conditions Cost Big $ We Have a Whole Lot of This 53% Good 53%46% 1% Good Fair Poor 72% 69% 73% 69% 61% 63% 64% 54% 53% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 2010 2011 2012 2013 2014 2015 2016 2017 2018 Pavement Condition: Interstates 35% Good 68% 67% 68% 63% 56% 54% 53% 41% 35% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 2010 2011 2012 2013 2014 2015 2016 2078 2018 Pavement Condition: NHS 35% 62% 4% Good Fair Poor 23% GoodPavement Condition: Non-NHS 44% 43% 43% 41% 36% 36% 35% 27% 23% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 2010 2011 2012 2013 2014 2015 2016 2017 2018 23% 71% 6% Good Fair Poor 78 75 75 69 64 63 65 65 59 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 2010 2011 2012 2013 2014 2015 2016 2017 2018 NHS Bridge Condition 59% 40% 1% Good Fair Poor 59% Good Keep the Good Good • Crack Seal • Flush • Pot Hole Repair (Delamination of 1” Asphalt Surface) Pavement Preservation - Flush New Asphalt Overlay Options Are Needed • What if we went back to a PCC Surface? • What if we could make the underlying PCC Pavement Surface better? • Would it/Could it last a lot longer with little need for maintenance or replacement? What if: Instead of? Tears Into the Concrete Damaged Joints from Typical Milling Kyrene Road Ramp Area Experiment (April 6, 2019) Distressed Rubberized Asphalt Rideable Surface in Good Condition SR101 EB Test Section (April 27, 2019) • 4 Test Sections • Diamond Grind, Next Gen, Skid Abrader & Micro-Mill • Ride, Sound, Appearance • What does the public think? SR101 EB Test Section (April 27, 2019) Diamond Grind SR101 EB Test Section (April 27, 2019) Next Generation SR101 EB Test Section (April 27, 2019) Skid Abrader SR101 EB Test Section (April 27, 2019) Micro-Mill SR 202 Diamond Grind Real Life Project (May 11, 2019) Loader to Remove Rubber Asphalt Small Diamond Grinders Finished Condition Maricopa Association of Governments MAG Report Considering the challenges the MAG region and state have had in recent years – and are projected to continue to have in the future – to secure adequate funding for roadway maintenance, consideration should be given to replacement of the rubberized asphalt overlay with a diamond grind treatment. Maintenance Procurement Contract • Contractor Prices bid items associated with diamond grinding SR 202 EB Go Big Project (February 2020) • 4 Mile Section • 4 Lanes Wide • Ramp Sections Included Cut Strips through Rubberized Asphalt to Control Milling Head Large Diamond Grinders 3 Grinders Working Side by Side Final Diamond Ground Product Rideable Quiet Looks Good Diamond Grind Pilot Projects • Loop 101 Price Freeway • Loop 101 Pima Freeway • Loop 101 I-17 to 75th Ave Projects Questions? Concrete Pavement Preservation Webinar 3 – Questions and Answers The questions submitted during the webinar follow with answers that our speakers have provided. Additional resources are available at https://cptechcenter.org/pavement-preservation/ 1. Can SCC be used for backfill of DBR slots? We find the best results are achieved using proprietary fast setting cementitious products designed for the special needs of a DBR. Strength development is especially important, not as much for reopening to traffic as much as developing strength before the diurnal temperature swings begin to move the concrete slabs, stressing the newly placed DBRs. Durability is also a big factor. These materials and suppliers can be found on the IGGA website www.IGGA.net. 2. Can the AZ DOT presenter talk about any urban heat island impacts that uncovering and exposing the concrete may have? The decision to remove the AR-ACFC was not based on climate impacts, but rather economics. With that said, concrete has a higher albedo and as such should reduce the urban heat island effect. However, urban island is a very complex phenomenon and the amount of exposed concrete as a result of the grinding will probably not impact this. 3. Can you please go into more details about how you removed the ARCP on the 4 miles of SR202 rehab project? I didn't quite understand the cutting strips to control milling head depth. As you are most likely aware, a milling machine simply dials in an asphalt removal number (in our case 1”) and goes to work. Unfortunately, there are often inconsistencies in the PCC and the 1” rubber course (high points & low points) which are not taken into consideration in a regular milling operation, often causing the PCC to be badly marred. By cutting strips in the 1” rubber course, the milling operators can see the depth they are required to cut (instead of just dialing in 1”) and can provide a less damaging effect to the underlying PCC. 4. Can you provide a guide book on best practices for diamond grinding and when it can be used to improve faulting or uneven concrete surface and when it may be best to use another technique such as dowel bar retrofit? There are numerous resources available on www.IGGA.net , www.ACPA.org , www.CPTechcenter.org ,and FHWA websites related to those topics. The following publication is a good starting point…. https://intrans.iastate.edu/app/uploads/2018/08/MAPbrief4-1.pdf 5. Can you suggest materials that could be used for PDR's? This is a very broad topic in that there are a number of different products and classifications… cementitious, polymer resins, elastomeric, etc. all with varying attributes, performance and prices. I suggest that you explore the PDR manual developed by the CPTech Center at the following link as a start, https://cptechcenter.org/pavement-preservation/ http://www.igga.net/ http://www.acpa.org/ http://www.cptechcenter.org/ https://intrans.iastate.edu/app/uploads/2018/08/MAPbrief4-1.pdf https://intrans.iastate.edu/app/uploads/2018/08/PDR_guide_Apr2012.pdf. The most widely used PDR materials and suppliers can be found on the IGGA website www.IGGA.net using the available search engine. 6. Could you please share treatments for ASR-related distresses and D-cracking, Some guidance is available in https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_ and_solutions_guide_w_cvr.pdf 7. Did the Arizona DOT get a lot of push back from the asphalt industry and how did they handle the political pressure with regard to that? Great Question, we are in fact getting some push back from the asphalt industry for moving forward with our diamond grinding operations. We are handling this by explaining that we have to make educated decisions with the limited maintenance and capital improvement funding we receive and other options are always on the table to be explored. The asphalt industry is aware that we do have some sections of PCC that are quite aged in Phoenix and will most likely be overlaid with 1” rubber for many future years. It is a bit of a balancing act. 8. Does diamond grinding or just grinds for smoothing compromise the aggregates and make them susceptible to ASR or salt intrusions that increase the rate of deterioration? AND WRT ASR, the exposed rock surface (if igneous) is going to expose a paste silicon dioxide interface that may be reactive, no? We are not aware of any authoritative research that shows that diamond grinding accelerates the onset of ASR deterioration or increases the rate of salt intrusion and have not encountered increased rates of materials related distresses due to the grinding process in the field. While it is true that the diamond grinding process removes the very thin paste fraction from the roadway surface, so does traffic over time exposing the coarse aggregates. Assuming that this concern is directed at older, existing pavements (since most newer pavements are not built with ASR-prone aggregates), it is likely that the coarse aggregates are already exposed. That said, pavements that are deteriorating rapidly due to severe materials related distresses are not likely candidates for grinding or significant preservation activities. 9. Does WsDOT have an average cost per SY of total pavement to do dowel retrofit? This cost needs to be calculated based on individual project conditions such as: project size, project location, available working hours, wage rates, aggregate type, existing smoothness, required smoothness, joint spacing, etc. An average cost even from a single state would be misleading. Costs can vary widely from project to project even within the same state. A good range to use for the individual DBRs is $35 to $45 per bar installed on a project with 25,000 bars. Prices will come down on bigger jobs. Assume 3 or 4 bars per wheel path depending on traffic loading and multiply times the number of joints. Grinding will typically range from $2.50 to https://intrans.iastate.edu/app/uploads/2018/08/PDR_guide_Apr2012.pdf http://www.igga.net/ https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_and_solutions_guide_w_cvr.pdf https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_and_solutions_guide_w_cvr.pdf $5.00 on average unless the aggregate is very hard and/or the required removal is excessive. 10. Fast setting concrete materials have been referred to frequently in this presentation. What is the track record on performance of these fast setting materials? Do they get the life that one would expect with a typical/normal concrete mixture? Has anyone tracked average life of slabs placed with fast setting (e.g. high early strength) materials? The performance track record on fast setting concrete materials used in the highway market has been scattered over time. Many of the so-called fast setting concrete products may set quickly but cannot stand up to the constant pounding of roadway traffic. In recent years new fast setting concrete materials have been specially developed to endure the harsh roadway environment and have been documented as performing very well. Dr. Mike Darter has done some work in this area and I believe that he will be presenting some of his findings in next week’s webinar series, Part 4 on Tuesday June 24, at noon CDT. These materials and suppliers can be found on the IGGA website www.IGGA.net. 11. For joint/crack sealing, we are hearing that it may be better to exclude the backer rod and just fill the joint/crack with sealant. The labor savings of installing the backer rod offsets the added material costs. The larger face also provides more opportunity for the sealant to bond with the concrete. AND I hear from others there is a concern about moisture trapped or attracted by backer rod. Should we consider sealing without backer rods? Yes there are several state DOTs that fill rather than seal their joints and report that this process works well for them. Transverse joints are a system that require design and a careful look at geometry, materials, past performance, cost and local contractor proficiency. In the end it is a choice to be made that best suites the owners. That is in fact true when using the improper backer rod. The use of backer rod NOT designed for use in roadway applications can hold water and result in premature deterioration at joint locations. This is not true when the proper backer rod is used. Water trapped in the kerf below a backer rod has been shown to accelerate joint distress. Further to the question, sealing without backer rod is essentially joint filling. There are a number of states that fill their joints rather than seal and report good performance. In the end this decision should be made based on local performance. 12. For the AZ diamond grinding projects, how are the slurry residuals handled? Shoulder applied or another process? For both projects to date, the contractor deposited the slurry in a lined ponds and let it decant (water evaporate). The current project is using an active quarry where it is being decanted. 13. How did you prepare the longitudinal interface (ie., stepping) between the diamond ground lanes and the 1" thick asphalt lanes? The contractor utilized a small grinding machine to taper the 1” asphalt to the ground PCC. The taper is approximately 8”-12” wide. 14. How does diamond grind impact the total lifecycle costing for concrete pavements? How will this impact your initial pavement selection moving forward? The answer to this question is based on performance in a given local and there is no single answer that will suit all situations. Life cycle costing should be based on data obtained from local survival curves, which are refined over time through local experience and fed back into the analysis. In general it is widely accepted that smoother pavements last longer, meaning that diamond grinding can prolong the life of a concrete pavement. 15. How does noise level of diamond ground concrete surface compare with asphalt surface from overlay? A conventionally diamond ground surface often times can be quieter than a dense graded asphalt surface. The Next Generation Concrete Surface (not discussed during the webinar) can outperform dense graded asphalt surface in terms of noise reduction. Our limited testing to date shows that new rubberized asphalt surfaces have an approximate 97db level when new and increase to 103-107db at the end of their life (typically 10 years). The diamond ground surfaces typically have an approximate 102db level when new and keep to that db level throughout their 15 years of typical life. 16. How much concrete was removed in the diamond grinding of 4 miles of 202 that Randy talked about? A good question and one I meant to answer in the presentation and neglected to. We typically ground approximately 3/8” to ¼” off the PCC surface. 17. I am hearing that some thin concrete overlays with 6x6' jointing are not doing joint sealing on interstate highways within freeze thaw areas. Is this wise? Recommended? While we continue to learn from each overlay built, it should be noted that the specific answer to the question about sealing or filling of joints for small panel overlays ranges widely from application to application and from agency to agency. Several states who did not seal joints early on have now revised standards to require sealing or filling. However, a number of states continue without sealing and have seen little reason to change that practice. 18. I had heard the term "next generation diamond grinding" a few years ago but never saw any samples. Was this term representing the diamond smoothing that was talked about earlier? The Next Generation Concrete Surface (NGCS) is a diamond saw cut surface texture that was specifically designed to reduce tire pavement noise while providing a smooth and safe exposed driving surface. The following file will provide some additional background. Visit IGGA.net for more information or: https://intrans.iastate.edu/app/uploads/2020/01/MAPbriefJanuary2020.pdf 19. I love the diamond grinding on the 101 south valley. It is so smooth and quiet. We are thrilled to hear that. One of the big factors for us, besides testing for noise and ride, is to gauge the reaction of the public who drive the roadway. The more comments like this, the more we will have support to continue these diamond grind projects. 20. Is DBR recommended anywhere a transverse crack occurs in a slab? No. If a transverse crack occurs close to a transverse joint, it is recommended to use full depth repair in that location. 21. Is diamond grinding always done in the longitudinal direction? Yes 22. Is it a common practice to do diamond grinding for new pavements, instead of tining? Diamond grinding as a final surface texture in new pavement is commonly used across the country. This is especially true on large, complex design build projects where there are heavily phased sections constructed over the period of years making it very difficult to maintain surface smoothness. Grinding is several decibels quieter than tining, removes any existing curl and warp extending pavement life and provides significant macrotexture for safety. 23. Is your flush process similar to a fog seal? It is the very same thing, just has a couple of different names. 24. Should curing compounds be used on partial and full depth repairs after the initial wet curing and prior to opening to traffic? Curing is an essential part of patching, especially on repairs using fast setting materials. Wet curing is not a common practice today however. Often times on partial depth repairs double application of modern curing compounds are required due to the depth to surface area ratio of the patch. Proper curing is critical. 25. Should the joints be air cleaned or water flushed before applying a sealant? Joint preparation specifications typically require sand blasting (follow by compressed air cleaning) or water blasting to clean the joint faces prior to sealant application. Both are effective provided the processes are carried out properly. 26. So do we have a LCCA of the 202 considering all the mitigations and follow up treatments? How does this revised estimate compare to the original LCCA to use concrete? A LCCA was not conducted for the original PCCP construction nor was one conducted for the placement of the AR-ACFC overlays. As mentioned, the AR-ACFC was a politically motivated noise solution. However, initial construction costs were https://intrans.iastate.edu/app/uploads/2020/01/MAPbriefJanuary2020.pdf recently used to develop network costs over time to compare the different options and their attendant costs. 27. So, is it no longer an accepted load transfer design tool to use large road stone >2.0" to create load transfer at control joints? Most pavements today are built using 1” or ¾” coarse aggregate and with dowels inserted for load transfer. Experience has shown that heavily trafficked systems without dowels may lose load transfer over time. 28. Using milling in partial-depth repairs does not provide straight-cut edges. Is it still recommended considering that feathering at the repair edges will be subject to quicker deterioration? Experience has shown that milled, feathered edges of PDRs perform very well over time (20 years + in MN) provided the loose material is removed from the edges using a jackhammer and the patch is sandblasted clean. Bear in mind however, some repair materials require saw cut edges to be used. https://intrans.iastate.edu/app/uploads/2018/08/PDR_guide_Apr2012.pdf 29. Was there a lip between the HOV and the diamond ground lane? Yes, there is a 1” lip between the two surfaces. The contractor utilized a small grinding machine to taper the 1” asphalt to the ground PCC. The taper is approximately 8”-12” wide. 30. What about thin bonded overlays? Overlays are an effective tool in the state’s toolbox. See the webinar series on overlays at https://cptechcenter.org/webinars-and-videos/ 31. What are your recommendations for success of joint resealing during the in-service phase of the concrete pavement (time interval to do and repeat) and design and material details to consider. This is a question that is a function of the type of material used, quality of installation and inspection, rainfall rates, traffic, base type, drainage, etc. The following ACPA Tech Bulletin is a good starting point. http://www.acpa.org/wp- content/uploads/2019/04/Jointing-Sealing-Tech-Bulletin-TB010-2018.pdf 32. What are your recommendations to address concrete pavement that has spalled and lost material at the edges (beyond sealing effectiveness) but the concrete still has structural capacity and there is still good support from the sub grade? Please give maintenance and capital work recommendations. This is a perfect application for partial depth repair followed by resealing. The INDOT has done some work investigating the PDR process in state and I am sure there are some local resources available. The steps will include sounding, mark-out, removal, cleaning, materials placement, curing and resealing (unless non cementitious materials are used). Detailed information is available in https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_ and_solutions_guide_w_cvr.pdf and https://intrans.iastate.edu/app/uploads/2018/08/PDR_guide_Apr2012.pdf https://cptechcenter.org/webinars-and-videos/ http://www.acpa.org/wp-content/uploads/2019/04/Jointing-Sealing-Tech-Bulletin-TB010-2018.pdf http://www.acpa.org/wp-content/uploads/2019/04/Jointing-Sealing-Tech-Bulletin-TB010-2018.pdf https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_and_solutions_guide_w_cvr.pdf https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_and_solutions_guide_w_cvr.pdf https://intrans.iastate.edu/app/uploads/2018/08/preservation_guide_2nd_ed_508_final .pdf 33. What is a good rule of thumb for the minimum spacing between full depth concrete repairs with dowel bar retrofits? If a transverse crack falls within 3 to 4 feet of a proposed full depth repair perimeter, it is best to incorporate the transverse crack repair as a part of the full depth rather than build a DBR so close. It is not cost efficient. 34. What is the average down time per mile to do dowel retrofit? It depends. Contractors have been able to install 1000 to 2000 DBRs in a single, 12 hour day. There are several steps and several pieces of equipment required to construct a DBR so a contractor will bring in as many people as necessary to meet the schedule. Asking for too much production can increase costs however. 35. What is the difference between diamond grinding and longitudinal tining? Diamond grinding is smoother, quieter and more uniform than longitudinal tining. Tining occurs while the concrete is still green and grinding occurs when the concrete is fully cured and at desired strength. 36. What is the life of preservation treatments? The following guide can shed some light on this question. https://intrans.iastate.edu/app/uploads/2018/08/preservation_guide_2nd_ed_508_final .pdf 37. What is the maximum (largest difference between slabs) amount of faulting between slabs that could be addressed using diamond grinding versus a different method like DBR? Diamond grinding can remove any amount of slab faulting, although it can be a slow process when removing extreme amounts of section. Even if the faulting returns you can choose to regrind. The DBR process is used to PREVENT future faulting by enhancing the mechanical load transfer between the slabs. The DBR is an additional investment but it is the longer-term solution. 38. What is the reasoning behind the statement that PCCP that has joint sealant installed, must continue with joint sealant replacement? Is there a situation where the joint sealant could be removed and the joint remain unsealed or open? Joints are an engineered system, from the drainage and dowel bars to the transverse saw cuts and sealant (or no sealant). Sealed joints typically are not tasked with transferring water to a drainable base ... they are there to keep the water and incompressibles out. Further, the joint reservoirs are typically widened to accommodate the sandblasting, backer rod, and sealant install operations. Conversely a no-seal system will likely have a different drainage design and will rely upon a much narrower saw cut, limiting the intrusion of incompressibles into the joint. A sealed (widened) joint reservoir that is switched to a no-seal system has greater potential to be impacted by incompressibles. The widened reservoir will also produce up to an additional 5dbA in noise when compared to a sealed system (assuming that https://intrans.iastate.edu/app/uploads/2018/08/preservation_guide_2nd_ed_508_final.pdf https://intrans.iastate.edu/app/uploads/2018/08/preservation_guide_2nd_ed_508_final.pdf https://intrans.iastate.edu/app/uploads/2018/08/preservation_guide_2nd_ed_508_final.pdf https://intrans.iastate.edu/app/uploads/2018/08/preservation_guide_2nd_ed_508_final.pdf the unsealed reservoir is over a ½ inch wide). Finally, the drainage capability of the system may be overwhelmed if one chooses to not seal a previously sealed joint reducing the life of the pavement’s foundation. In short there may be situations where the sealant can be removed and remain unsealed but one must be confident that the factors listed above are accounted for. 39. What is the status of the asphalt rubber paving program in Arizona? I know that at one time AZ had a large rubberized program, what is the status today? The status of the asphalt rubber paving program in Arizona continues to be fairly strong. ADOT still utilizes the 1” rubber asphalt overlay on most sections of PCC that is over 20-25 years (I-10, I-17) in age because at that age, it is more susceptible to damage from diamond grinding. Diamond grinding is being strongly considered on the younger PCC surface layers (certainly those <20 years old). 40. What materials do they use for pavement markings on the diamond ground surface? Typically, we use contrast stripe tape for all the center skip lines and thermoplastic for the edge lines, gore lines and the puppy skips adjacent to the auxiliary lanes. 41. What was the bonding technique used for the rubber 1" overlay. Why did this lead to delamination? A tack coat is used as the bonding agent between the 1” rubber overlay and the PCC. Our information shows that some of the delamination is caused by poor tacking application and some is simply caused by the age of the rubber. In some cases where the rubber is 5 or more years older than its service life, the rubber has simply raveled away. 42. What was the cost per SY for diamond grinding both the pilot and the large scale efforts on the 202? Our Maintenance procurement contract has a diamond grind price of $5/SY. This is the price we paid for the work on the Loop 202 project. For our other two pilot projects on Loop 101 we have received prices from the contractors for $5.50/SY and $4.75/SY. 43. What was the MOT used for the 202 diamond grinding project and how did the travelling public react to the MOT? How long were lanes closed? The entire Loop 202 EB was shut down for the milling operation and startup of the diamond grinding operation. As the diamond grinding operation progressed, the MOT changed to 2-lane closure scenarios. The traveling public complained very little about the MOT because they realized how deteriorated this section of freeway was and how much it needed attention. ADOT does a pretty good job of giving the traveling public plenty of up front information regarding closures. 44. When you say 'rubber mix', what do you mean? Is this a polymer or true recycled rubber asphalt blend? We typically use a recycled asphalt rubber blend made literally from old tires. We are starting to look into polymer blends, but we have not used these on a wide scale at this time. 45. Why select diamond grinding only? What other treatments were considered in Phoenix area? As the presentation showed, ADOT did consider and pilot other methods. We analyzed test sections of diamond grind, next generation grinding, skid abrading, and micro-milling. Ultimately, we settled on diamond grinding after considering a number of factors including cost, ride, sound, appearance, and public opinion. 46. Why did ADOT cover their concrete pavement with the rubber overlay to begin with? As one of the slides showed, in 2003, the travelling public was complaining loudly about the noise level of transversely tined PCC. The political solution was to overlay all PCC in the Phoenix area with AR-ACFC rubber mix. 47. Why don't you seal the pavement surface? If you are referring to sealing the asphalt rubber surface in Phoenix, keep in mind it is meant to be an open graded surface so we don’t intentionally seal it. However, the flush or fog seal coat we apply to regenerate the rubber mix does have a tendency to fill some of the voids and cause some sealing of the asphalt. The fog/flush coats do extend the life of the 1” rubber mix, but only for so long. 48. Would you consider diamond grinding for panel warp or faulting without dowel retrofit? Yes, but it depends on a number of factors. Age, base type, traffic etc. A number of states prefer to simply regrind if faulting reoccurs rather than invest in DBR to prevent future faulting. As for panel warp, grinding is almost always the go-to option. DBR is not a consideration in most cases when grinding out curl or warp. 49. Would you have recommendations on how to address longitudinal joint faulting (where new PCCP was placed against old PCCP and now there is an elevation difference)? The structural deficiencies should be dealt with using either cross stitching or slot stitching to arrest the differential settlement. Once completed the pavement surface should be realigned utilizing diamond grinding for smoothness. https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_ and_solutions_guide_w_cvr.pdf https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_and_solutions_guide_w_cvr.pdf https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_and_solutions_guide_w_cvr.pdf Concrete Pavement Preservation Webinar 3 – Questions and Answers | |
| 2. Concrete Pavement Evaluation and Preservation Strategy Selection | 👤 Steve Tritsch 👤 John Donahue | Concrete Pavement Technology Tuesday Webinar PAVEMENT PRESERVATION WEBINAR SERIES | 2020 |
| 2020-06-09 | 6/12/2020 1 Concrete Pavement Evaluation Concrete Pavement Preservation II Purpose of a Pavement Evaluation • Provides qualitative information to: • Determine causes of deterioration • Determine if pavement is not a candidate for preservation • Develop appropriate alternatives • Provides quantitative information for: • Quantity estimates • Assessment of deterioration rates • Performing life-cycle cost analyses 2 Extend the Service Life in Good Condition 6 LONG-TERM PAVEMENT PDR and/or DG Project Evaluation Approach • Historical data collection/records review • Initial site visit and assessment • Field testing activities • Laboratory materials characterization • Data analysis • Final field evaluation report 4 6/12/2020 2 Key Pavement Evaluation Components • Pavement Distress & Drainage Surveys • Nondestructive Testing • Surface Characteristics Testing • Field Sampling and Testing 5 Purpose of Distress Survey • Document pavement condition • Identify types of distress characterized by severity and extent • Group areas of similar performance • Gain insight into causes of deterioration • Identify additional testing needs • Identify possible treatment alternatives • Identify repair areas and quantities 6 Distress Identification Manual • Standardized distress definitions • Benefits • More consistent calls • Better communication within and between highway agencies • Improvements in any agency activity using pavement performance information 7 Example Distress Manuals 8 6/12/2020 3 Output of Distress Surveys • Distress types and quantities • Overall indicator of condition (PAVER, PASER, State DOT procedures) VERY GOOD FAIR POOR FAILED VERY POOR PCI 100 85 70 55 40 25 10 0 Repair Type Preventive Maintenance Minor to Major Rehabilitation Reconstruction GOOD EXCELLENT Example Index 9 Common Concrete Pavement Distresses • Corner Breaks • D-Cracking or ASR • Transverse Cracking • Spalling • Patch/Patch Deter. • Joint Faulting • Pumping • Joint Seal Damage • Blowup • Map Cracking • Punchout • Scaling • Longitudinal Cracking 10 Common Concrete Pavement Distresses 11 corner crack D-cracking transvers crack joint spalling patch deterioration faulting pumping joint seal damage blowup map cracking punchout (CRCP) scaling longitudinal cracking Longitudinal Cracking 6/12/2020 4 Chapter 6. Longitudinal Cracking 2. Severity Table 6.1 Severity levels of longitudinal cracking 13 Example Distress Form Blank Filled Out 14 Drainage Survey • Purposes: • Identify moisture-related distress • Document drainage conditions • Assess overall pavement drainability • Things to look for: • Topography and cut/fill • Pavement/shoulder slopes • Condition and geometrics of ditches • Condition of drainage outlets or inlets 15 Nondestructive Testing • Not needed on all pavement preservation projects • Information can be confirmed such as thicknesses, pavement properties, load transfer capabilities, voids, and embedded steel alignment • Can have significant testing and analysis costs 16 6/12/2020 5 Deflection Testing • For pavement preservation work, valuable tool for assessing: • Joint load transfer • Presence of voids • Structural adequacy • Fast and produces repeatable results • Commonly used in project-level analysis 17 Use and Interpretation of Deflection Data • Deflection uniformity along project • Backcalculation of pavement properties • Evaluation of joint/crack load transfer • Void detection 18 Ground Penetrating Radar (GPR) • Determine layer thickness • Embedded steel location • Presence of underlying voids Layer Type Accuracy (vs. Cores) New Asphalt 3 – 5% Existing Asphalt 5 – 10% Concrete 5 – 10% Granular Base 8 – 15% 19 Magnetic Imaging Tomography (MIT) • MIT Scan-2 • Evaluate dowel bar location and orientation • MIT Scan T2 • Determine concrete slab thickness 20 6/12/2020 6 Ultrasonic Tomography (MIRA) • Layer thickness • Relative concrete strength • Cracking in the concrete layer • Debonding between concrete layers • Location of embedded steel • Areas of joint deterioration and poor consolidation 21 Roughness Surveys • Measures actual pavement profile • Widespread use in network- level pavement management • Relatively accurate and repeatable measurements 22 Testing Equipment Non-Contact Lightweight High-Speed Profiler Portable Laser 23 Roughness Indicators Ride Quality IRI (in/mi) PSR Good < 95 > 3.5 Acceptable < 170 > 2.5 Not Acceptable > 170 < 2.5 • International Roughness Index (IRI), current measurement standard • Pavement Serviceability Rating (PSR) • General correlations: 24 6/12/2020 7 Friction Surveys • Assess overall adequacy of pavement friction as it contributes to safety • Identify localized areas with poor friction • Curves • Intersections • Ramps 25 Assessing Surface Friction • Measure surface friction directly with various devices (e.g., skid trailer) • Must also consider surface texture • Microtexture • Macrotexture 26 Measuring Surface Texture • Volumetric (“Sand Patch”) method • Outflow Meter • Circular track meter (CTMeter) • High-speed laser-based devices 27 Tire/Pavement Noise Survey • Emerging as a critical issue, especially in high-volume urban areas • Problematic to adjacent property and business owners and the traveling public • On-Board Sound Intensity (OBSI) method 28 6/12/2020 8 Purpose of Field Sampling and Testing • Purposes: • Determine layer thicknesses • Characterize material properties • Diagnose causes (mechanisms) of distress • Can consist of: • Field sampling • Field testing • Laboratory testing 29 Common Field Sampling and Testing Methods • Coring • Material sampling • Dynamic cone penetrometer (DCP) • Standard penetration testing (SPT) 30 Common Laboratory Tests • Subgrade and granular base/subbase • Characterization (soil classification, moisture content) • California Bearing Ratio (CBR) • Resilient Modulus (Mr) • Stabilized layers and PCC slab • Indirect Tension • Unconfined Compression • Special Materials Evaluation Tests 31 Then and Now Distress Identification • Discrete Test Locations (Sampling) • Manual Data Collection & Analysis • Limited Computing Capacity • Field Reviews Only • Guestimates of Climate Data • Little to No Ability to Evaluate Products or Test Sections • Linear MP Location Data • 2D Profile Measurements • Limited to No Maintenance Data • Questionable Traffic Data Then Now • 100% Roadway Coverage • Automated Data Collection & Analysis • Almost Unlimited Computing Capacity • In-Office Visual Review of Roadways • Accurate Environmental Data • Ability for PMS to Test Sections and Products • GPS Coordinates • 3D Profile Measurements • Exact Maintenance Locations and Costs • Better Traffic Data? 30 6/12/2020 9 Additional Information • Introduction • Preventive Maintenance and Pavement Preservation Concepts • Concrete Pavement Evaluation p. 17-57 • Slab Stabilization and Slab Jacking • Partial-Depth Repairs • Full-Depth Repairs • Retrofitted Edgedrains • Dowel Bar Retrofit, Cross Stitching, and Slot Stitching • Diamond Grinding and Grooving • Joint Resealing and Crack Sealing • Concrete Overlays • Strategy Selection Will be updated 4th quarter 2020 33 Thanks for your time 34 1 Concrete Pavement Evaluation for Restoration John Donahue, P.E. Construction and Materials Liaison Engineer CP Tech Center Preservation Webinar June 9, 2020 PCC Restoration History in Missouri • Missouri had traditionally addressed pavement distresses in new and existing PCC pavements with full depth repairs or asphalt overlays. • Often, the magnitude of the solutions were disproportionate to the severity of the distresses. • A move to employ alternate, less intrusive preservation, repair, and rehabilitation treatments began in the early 2000’s. • PCC restoration techniques have yielded short‐to‐long term performance benefits. I‐35 JRCP in Clinton County with Asphalt Overlay Milled Only do what’s necessary! 2 PCC Pavement Evaluation Considerations • Distress severity • Location of distresses • Age of PCC pavement • Depth of reinforcement • Load transfer • Aesthetics • Estimating quantities Distress Severity Full depth repairs should be a last resort! Primarily for – • Shattered slabs • Severe spalling • Internal degradation (D‐cracking, ASR, etc.) I‐35 Shattered Slab 3 I‐64 Joint Spalling D‐Cracking Low Air Content Short‐Term Solution 4 US 412 in Dunklin County JD2 Do nothing? PDR Candidate PDRs on US 63 in Randolph County 5 Location of Distresses US 36 in Macon County 8’ EB US 36 ¢ # 10 # 7# 8# 9 Panel 216 Panel 215 Panel 214 2’ 43” Median Side 42” 5’ 54” 6 Age of PCC Pavement Rte 105 in Charleston at 47 Years 65‐Year Old Pavement!! 45‐Year Old JRCP No Mid‐Panel Cracks 7 7‐Year Old Unbonded JPCP Overlay Interior Punch‐out No Interlayer !! Epoxy Repairs on US 36 8 Depth of Reinforcement JRCP Wire Mesh Placement ‘Manual’ Depth Adjustments Checking Depth of Steel Reinforcement 9 Not a grinding candidate! Ignore? Load Transfer FWD Load Transfer Testing 10 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 A ve . L o a d ( lb ) Ave. Deflection (mils) US 71 NB at Bridge A-2022 in Jasper Co. 3rd Approach Slab Before Undersealing After Undersealing US 67 in Butler County I‐35 JPCP Faulting Inadequate Dowel Bar Embedment 11 Rte 94 in St. Charles County Longitudinal cracking and faulting New FillOld Fill AC Millings Faulting February 2013 March 2009 Heavy Duty Cross‐Stitching Aesthetics 12 I‐55 Exit Ramp in Scott County Slab T/2 T Crack 24” Cross‐sectional View 2 ½” min End View US 63 Mudballs 13 Cross‐stitching appearance Estimating Quantities Scoping Repair Quantities •Generally, repair quantities can be expected to increase ~ 10% from the time of project scoping to the award of contract, so roadway designers should set up plan quantities accordingly. •Logmile or GPS coordinates for repairs should be included. •May (or not) add other preservation treatments as contingency. Field Inspector Reviews •After a project is let, plan quantities for repair work will probably require modifications based on real time conditions. •Construction inspectors will increasingly find themselves making repair decisions on the fly and therefore should have a general understanding of concrete restoration treatments and triggers. •Project construction engineers must make decisions to stay within the contract budget. 14 Thank you! Questions? john.donahue@modot.mo.gov (573) 526-4334 Concrete Pavement Preservation Webinar 2 – Questions and Answers The questions submitted during the webinar follow with answers that our speakers have provided. Additional resources are available at https://cptechcenter.org/pavement-preservation/ 1. Which states use PCI (Pavement Condition Index) most for maintaining highways? Texas? It is believed that many states, local agencies and airports also use PCI. https://www.fhwa.dot.gov/pavement/preservation/pubs/perfeval/chap06.cfm https://www.fhwa.dot.gov/asset/pubs/hif11035/hif11035.pdf 2. When a deteriorated pavement section is repaired by a full depth patching, Contractor prefers flowable fill, lean concrete in lieu of aggregate base because it is easier to compact corners, is that right?" Flowable fill is essentially self-consolidating so it is a correct statement that it is easier to compact the corners. It’s often used for utility repairs. For supporting a full depth repair slab, either flowable fill or lean concrete should be adequate. However, the weaker concrete in the substrata may bond with the FDR slab and be susceptible to a fracture stress point, which emanates as a crack through the monolithic slab. 3. Are there any standards that guide through the process of pavement condition evaluation using techniques such as GPR, magnetic, and ultrasonic tomography? Concrete Pavement Preservation Guide and Guide for Concrete Pavement Distress Assessments and Solutions: Identification, Causes, Prevention, and Repair both provide additional guidance. https://intrans.iastate.edu/app/uploads/2018/08/preservation_guide_2nd_ed_508_final .pdf https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_ and_solutions_guide_w_cvr.pdf 4. Do you recommend sealing the joint? There are caveats to this question that influence the decision • Joint spacing as well as joint width • Base and subgrade type and permeability • Precipitation levels and climate (freeze/thaw) • Potential for incompressibles • Traffic volume and speed Some states do not seal joints where high speed traffic is the norm and the joints are narrow. In urban areas where slower traffic is typical, the joints are sealed as https://cptechcenter.org/pavement-preservation/ https://www.fhwa.dot.gov/pavement/preservation/pubs/perfeval/chap06.cfm https://www.fhwa.dot.gov/asset/pubs/hif11035/hif11035.pdf https://intrans.iastate.edu/app/uploads/2018/08/preservation_guide_2nd_ed_508_final.pdf https://intrans.iastate.edu/app/uploads/2018/08/preservation_guide_2nd_ed_508_final.pdf https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_and_solutions_guide_w_cvr.pdf https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_and_solutions_guide_w_cvr.pdf incompressibles have been observed on those roadways. PCCP overlays with short joint spacing, such as 6’ x 6’ with single saw cuts, are not normally sealed. In Missouri, we generally only seal joints if they open a ¼” or more, in order to prevent infiltration of incompressibles. Each DOT should base this decision on their experience and engineering judgment. 5. For partial depth repair, what type of tool is used to remove loose material to minimize damage to the adjoining concrete that may fail in future? Two procedures are used: use of a small milling machine; or a perimeter saw cut is made with the interior chipped out with small lightweight chipping hammers (to mitigate the potential to break thru the slab). Generally, a light (~ 35-lb) jackhammer should be sufficient for concrete removal w/o damaging the adjacent area. 6. How do we quantify/measure incompressible materials in unsealed transverse joints and sealed joinst that have their sealant damaged? The following is from the Guide for Concrete Pavement Distress Assessments and Solutions: Identification, Causes, Prevention, and Repair, p. 268: https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_ and_solutions_guide_w_cvr.pdf “Assess Joint Sealant Condition—…if there are any signs of joint sealant damage, or if any other treatment alternatives have caused the effectiveness of the joint sealant to be compromised to a significant extent (e.g., 25 percent or more of the seal length has adhesion or cohesion failures or contains incompressible material), joint resealing should be considered.” 7. Do incompressible materials cause JPCP buckling? They can be a contributing factor. 8. How do you differentiate between load transfer or void problems when looking at FWD data for a plain dowelled concrete pavement? Poor load transfer and voids under slab edges often occur together in the same location, but are not completely dependent on each other. Voids can be detected by plotting load versus deflection for three FWD drop heights and determining where the trend line intercepts the deflection axis. Typically, an intercept of ~ 5 mils or higher is indicative of a void under the edge. Load transfer efficiency (LTE) is simply the ratio of the unloaded and loaded slab edge FWD deflections. The defining ratio for poor load transfer varies, but is usually between 60 and 70 percent. LTE testing should be performed when the slab temperature is below ~ 60⁰ F to avoid joint lockup. 9. It is not practical to inspect each and every slab during field distress evaluation. What are some practical guidelines to go about distress survey sampling? Correct, it is not practical to test every slab for nearly any DOT. One workaround is a statistical sampling, such as performing load transfer testing every tenth joint, which can determine probable sections within the project limits that require undersealing and/or dowel bar retrofit (DBR) quantities. Another option is visually identifying https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_and_solutions_guide_w_cvr.pdf https://intrans.iastate.edu/app/uploads/2019/01/concrete_pvmt_distress_assessments_and_solutions_guide_w_cvr.pdf symptoms of poor load transfer, such as pumping of fines on the shoulder, and limiting FWD testing to those zones. 10. John: is JRCP still constructed in Missouri?, The last JRCP in Missouri was completed in the early 1990s. 11. Network level deflection data is being collected and has been collected for a decade in other countries. It isn't just project level. Noted 12. States of had up to 15 years performance from full depth repairs. Noted 13. Thought that GPR is affected by the presence of rebar or WWF that prevents penetration of the waves beneath the steel inclusions? From p. 445 Guide for Concrete Pavement Distress Assessments and Solutions: Identification, Causes, Prevention, and Repair: GPR uses the amplitude and time of a radio pulse to analyze the slab thickness, location of embedded steel, detection of voids under the slab, location of defects, or changes in the overall pavement structure… The presence of contrasting materials within the concrete are more readily discernible with GPR. 14. What mechanism of grinding is used for concrete pavement with reinforcement? Same operation as with any other pavement. Just have to know if there will be sufficient cover over the steel once grinding is complete. 15. You can also do edge drain inspections with a camera. This should be done every 5 years or so to ensure they haven't been silted up or rooted. Damage can also be detected after construction for crushed drains. Noted Concrete Pavement Preservation Webinar 2 – Questions and Answers | |
| 1. Concrete Pavement Management and Preservation | 👤 Larry Scofield 👤 Angela Folkestad | Concrete Pavement Technology Tuesday Webinar PAVEMENT PRESERVATION WEBINAR SERIES | 2020 |
| 2020-06-02 | Concrete Pavement Management and Preservation Larry Scofield, IGGA/ACPA 1 Presentation Outline • Defining Pavement Performance • Beginning of Pavement Management • Concrete Pavements Outlast the Generation That Builds Them • Portrayal of Pavement Performance • So What is Different Today • ACPA Survey of State PMS Practices (Sept 2016) • FHWA P2 ETG Survey of PMS Practices (March 2017) • Dat |