Low Cracking High Performance Concrete (LC-HPC) Bridge Decks

This paper describes how research over the past 35 years has provided specific guidance on modifications in materials and construction techniques that will reduce the amount of cracking in bridge decks. Research is currently underway in conjunction with 15 state Departments of Transportation and the Federal Highway Administration that includes the construction of 20 low cracking high performance concrete (LC-HPC) bridge decks for which best practices are applied in order to minimize cracking. Techniques to reduce cracking include a reduction in the volume of cement and water, maintaining an adequate air content, optimizing aggregate gradations, deemphasizing the importance of high compressive strength and low concrete permeability, controlling the temperature of the concrete at the time of placement, minimizing evaporation during placement, improved curing, and reducing the rate of drying after curing is complete. The strategies used to minimize cracking are described, along with the results for the initial bridge decks constructed in the program.