Characterization of Interface Bond of Ultra-High-Performance Concrete Bridge Deck Overlays

Critical components of the nation's bridge network, concrete bridge decks, are deteriorating at a rapid rate. This deterioration can be attributed to several factors; however, winter salt application, the diffusion of chlorides to the reinforcing steel, and eventual corrosion of the reinforcement are primary culprits. Multiple protection solutions, include concrete protective systems, sealers, additional cover to the reinforcement, membranes, and epoxy-coated reinforcement, but each solution has shortcomings and does not completely address the problem. Ultra-high-performance concrete, a relatively new material with exceptional strength and durability characteristics, may be a solution to these problems when it is used as a thin overlay on bridge decks. An experimental study was performed to evaluate the bond strength between an ultra-high-performance concrete overlay and a normal concrete substrate with different types of surface textures, including smooth, low roughness, and high roughness. Slant shear and splitting prism tests were performed to quantify the bond strength under compression combined with shear and under indirect tension. Test results demonstrated that under compressive loading, the bond strength was greater than the strength of the substrate when the surface texture was greater than the standard smooth finished mortar surface. For the bond strength under indirect tension, results were not highly sensitive to the surface roughness. In both cases, the measured bond strengths fell within the ranges specified in the American Concrete Institute's Guide for the Selection of Materials for the Repair of Concrete.