LAUSR

Abstract Externally bonded (EB) fiber reinforced polymer (FRP) composites have been effectively employed to strengthen existing reinforced concrete (RC) structures. However, relatively limited information is available regarding the long-term behavior of FRP-concrete joints. In this paper, different experimental tests are employed to investigate the effect of hygrothermal ageing on the bond behavior of a carbon FRP composite applied to a concrete substrate and on the mechanical properties of the epoxy resin and FRP composite considered. The experimental campaign includes tensile tests of epoxy resin, carbon FRP (CFRP) coupon, pull-off tests of the CFRP bonded to the concrete substrate, and single-lap direct-shear tests of CFRP-concrete joints. Specimens were conditioned in warm water (38 ± 2 °C) for 500, 1000, and 1500 h to accelerate the possible degradation induced by a simulated high-moisture exposure environment. The parameters studied were the tensile properties of epoxy resin and CFRP coupons and the fracture energy of the CFRP-concrete interface, which was computed from the CFRP strain measured in the single-lap direct-shear tests using the digital image correlation (DIC) method. Results indicate that both the mechanical properties of the epoxy resin and the CFRP-concrete interface fracture energy were slightly affected by the exposure conditions.