Bond behavior of CFRP sheet-concrete interface using externally bonded reinforcement on groove

To study the interfacial bond behavior of carbon fiber rcinforced polymer (CFRP) material bonded on the groove region after the concrete grooving, a singlc shear test was condueted on 16 groups of concrete speeimens reinforced by CFRP sheets externally boned on groove with main Parameters, including the groove width, depth and concrete strength grade. In parallel, 4 sets of concrete speeimens with CFRP sheets externally bonded on concrete surface were designated as control groups. By analyzing the load-displacement curves, stress distribution characteristics and failure phenomenon of specimens during the test, the changing trends of Parameters such as the ultimate load, bond strength, maximum shear stress and maximum slip of specimens were explored, the influences of groove size and rcinforcement method on the failure mode of specimens were discussed, and the failure causes and mechanisms of specimens were analyzed. Based on the fitting results from the test data, the bond-slip model and the maximum shear stress calculation model of concrete specimens reinforced with CFRP sheets externally bonded on groove were developed, and the prediction results of maximum shear stress were compared with results in literatures. The research results show that in comparison with the reinforcement method without groove, the reinforcement method of CFRP sheets externally bonded on groove can effectively augment the ultimate load of the concrete specimen's bonding interface. The failure modes of specimens mainly present as bonding failure, CFRP sheets fracture failure, and composite failure. As the groove size increases, the maximum shear Stresses and peak slips of specimens reinforced by externally bonded reinforcement on groove (EBROG) within the groovcd region experience a significant increase, and there exists an optimal combination of groove width and depth. The deviation between the prediction results of the proposed calculation model for the maximum shear stress and the test results in relevant literatures is within 16%. Therefore, this model can be applied to prediet the maximum shear stress in the groove region.