Performance specification for high performance concrete overlays on bridges

Hydraulic cement concrete overlays are usually placed on bridges to reduce the infiltration of water and chloride ions and to improve skid resistance, ride quality, and surface appearance. Constructed in accordance with prescription specifications, some overlays have performed well for more than 30 years whereas others have cracked and delaminated before the overlay was opened to traffic. The use of performance specifications should increase the probability that concrete overlays will be constructed with high bond strengths and minimal cracks and will perform well for many years. The report describes the Virginia Department of Transportation's (VDOT) first experience with the use of a performance specification for the construction and acceptance of a high performance concrete overlay. Acceptance and payment were based on measurements for air content, compressive strength, permeability to chloride ion, and bond strength. Target air contents, high compressive strengths, low permeability, and good bond strengths were maintained throughout the project. Performance specifications with adjustments to the compensation specified in the contract likely influenced decisions made by the contractor and material supplier, and VDOT obtained a better product. VDOT should use the performance specification developed for this project for future bridge overlay projects.