Effect of Freeze-Thaw Cycles on FRP-Concrete Bond Strength in EBR and EBROG Systems

The effects of freeze-thaw cycles on the fiber-reinforced polymer (FRP)-to-concrete bond strength were investigated using the particle image velocimetry (PIV) technique. For this purpose, 18 specimens were prepared, including 12 specimens strengthened with carbon FRP (CFRP) strips as well as six control specimens subjected to 200 and 500 freeze-thaw cycles. The specimens were strengthened via externally bonded reinforcement (EBR) and externally bonded reinforcement on grooves (EBROG) methods. The results of PIV measurements revealed that, compared with the specimens strengthened via the EBR method, the EBROG-strengthened specimens exhibited considerably enhanced bond performance. When subjected to 200 and 500 freeze-thaw cycles, the EBR-strengthened specimens experienced a 3% and 9% decrease in their bond strength, respectively; the EBROG-strengthened specimens experienced no decrease in bond strength and increases in the range of 7%-19% when subjected to 200 and 500 cycles, respectively.