Fiber Reinforcement for Latex-Modified Concrete Overlays

Project Details
STATE

NC

SOURCE

TRID

START DATE

08/01/19

END DATE

07/31/21

RESEARCHERS

Gregory Lucier, Mohammad Pour-Ghaz

SPONSORS

North Carolina Department of Transportation

KEYWORDS

Bridge decks, Concrete overlays, Cracking, Fiber reinforced concrete (FRC), Latex modified concrete, Rehabilitation (Maintenance), Shrinkage

Project description

A large number of bridge deck rehabilitations are performed each year in North Carolina. Latex Modified Concrete (LMC) and LMC–Very Early Strength (LMC-VES) are frequently used in these rehabilitations because these materials provide reasonable installed performance and allow for a rapid return to service. Over the last 5 years, the North Carolina Department of Transportation (NCDOT) has completed an average of about 25 overlays per year using LMC or LMC-VES materials. The vast majority of these projects are highly successful. However, despite comprehensive NCDOT guidelines and specifications (such as PSP003 and PSP004), substantial cracking is sometimes observed in these overlays shortly after installation. Prior research funded by NCDOT has indicated that if placement and curing follows proper construction procedures, then the primary causes of cracking (such as shrinkage and plastic shrinkage) in LMC and LMC-VES materials are unlikely to develop. However, other secondary mechanisms can potentially cause cracking, including vibration of the structure during casting and curing, temperature changes during casting, and slight differential settlement/deflection of supporting decks as overlay placement progresses across a bridge.
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