Durability of CFRP–concrete joints under freeze–thaw cycling

The long-term durability of fiber reinforced polymer (FRP) strengthening systems under freeze–thaw cycling is crucial to the safety of structures in cold climates. The durability of the FRP–concrete bond interface under freeze–thaw cycling was investigated in the study reported here, with exposure condition, concrete grade, and number of freeze–thaw cycles as the parameters considered. The behavior of the carbon FRP (CFRP)–concrete bond interface was investigated with single-face shear tests. The results indicate that the bond strength, bond stiffness, interfacial fracture energy, and maximum slip of the joints decrease with increases in the number of freeze–thaw cycles, and they are also affected by the exposure environment. The depth of cracking and effective bond length increase with increases in cycle number, thus affecting bond stiffness and strength. The deterioration of bond strength can be attributed to the damage caused to the concrete by the freeze–thaw cycling.