Elizabeth Rose Bales, Venkatasaikrishna Chitrapu, Madeleine M. Flint
Virginia Department of Transportation; Federal Highway Administration
Bridge decks, Chloride exposures, corrosion resistant reinforcement, mixture variation, predicted service life
High costs and traffic disruption associated with the deterioration of reinforced concrete bridge decks because of corrosion have sparked renewed interest in service life design. Reinforced concrete bridge decks are exposed to chlorides from deicing salts; when the chlorides reach the steel reinforcement, they initiate corrosion. This study supports the adoption of the methodology described in fib Bulletin 34, Model Code for Service Life Design, for reinforced concrete bridge decks in Virginia. As part of this study, concrete mixture properties and environmental exposure conditions were characterized. Values particular to regions within Virginia and suggested default values were identified and organized in a database to support the development of service life design guidelines. The predicted service life for eight bridge decks using low-cracking concrete and corrosion-resistant reinforcement (VDOT Reinforcement Class I, MMFX, ASTM 1035) was evaluated. The service life model was also implemented in a life-cycle cost analysis for a case study bridge, which found superior reliability of corrosion-resistant reinforcement from a life-cycle perspective.In addition to supporting the implementation of service life design, several investigations identified key assumptions and variables in the service life model and identified critical areas for future characterization. Aging coefficients based on curing were also considered. A sensitivity analysis identified the aging coefficient and the surface chloride concentration as the most critical variables. The study concluded that sufficient data are available to implement the fib Model Code for Service Life Design, but that caution in interpreting results is warranted because of the high uncertainty associated with the most critical variables. . The use of corrosion-resistant steel and low-cracking concrete mixtures can provide a substantial (greater than 100 years) bridge deck service life.