Bridges, Tunnels and other Transportation Structures
Full Session with Abstracts
Ultra-high-performance concrete (UHPC) has been introduced for reinforced concrete structures due to its enhanced mechanical performance including high compressive strengths and tensile compacity. In certain applications such as at closure joints, connections, and concrete repairs, reinforcing steel may be embedded in dissimilar concrete elements partially incorporating the UHPC. Superficially, UHPC can be considered to provide enhanced corrosion durability in marine environments due to its low permeability which would mitigate chloride-induced corrosion of rebar in the bulk material. However, the localized galvanic effects of steel in dissimilar concrete in aggressive environments can be important. For example, steel embedded in the concrete perimeter of repair patches can undergo premature corrosion failure after repair due to the halo effect. This research, exploring the corrosion durability of steel embedded in dissimilar concretes incorporating UHPC, examines the extent to which enhanced chloride transport may occur at the cold joint. The effectiveness of the bond at the concrete interface (with various levels of moisture availability at the time of UHPC repair) to minimize chloride penetration was examined. To this effect, the substrate concrete was conditioned to moisture content (5%, 75%, 100% RH, and wet) prior to UHPC repair concrete casting. Chloride penetration was accelerated by impressed current, and chloride content was assessed by concrete sampling at the cold joint, as well as in the bulk concrete, and potentiometric titrations.