Bond Properties of FRP-concrete Interface with Nano-modified Epoxy Resin under Wet-dry Cycles

The interface bonding properties of FRP-reinforced concrete under wet/dry conditions are studied by performing the interface bond test. The effects of the number of wet/dry cycles and FRP layers, and FRP reinforcing sequence on the efficiency of reinforcement are studied. The microstructure of FRP-concrete interface is observed by SEM. The variations in bond properties of FRP-concrete interface under extreme conditions under tension are investigated. Experimental results show at the early stage of wet/dry cycles, the strengths of concrete and epoxy resin increase, and further interface bond strength enhances. As wet/dry cycles forward, defects and loose microstructure form in both FRP and concrete, and the interface bond strength decreases. Under identical conditions, the interface bond strength of sample strengthened by FRP after wet-dry cycles is higher than that of sample strengthened before wet-dry cycles. FRP-concrete bond strength is related to the number of wet-dry cycles.