Study on bond-slip degradation model of CFRP and concrete interface under sulfate erosion environment

Sulfate erosion of concrete is a kind of salt erosion which causes great harm to materials. It is also one of the important factors affecting the degradation of carbon fiber reinforced polymer (CFRP)-concrete interface. In this study, the sulfate environment was simulated by the sulfate dry-wet cycle accelerated erosion test. The bonding properties of CFRP-concrete interface under the dry and wet cycle of sulfate were studied by using 18 double-sided shear specimens. The variation trend of interface failure characteristics and interface characteristic values (interfacial shear stress peak and its corresponding slip amount) with sulfate erosion time were analyzed, and the interface bond-slip relationship curves under different erosion times were obtained. Based on the statistical regression analysis of the experimental results, the relationship between the interface ductility parameters and the interface eigenvalues as a function of sulfate erosion time was obtained. Moreover, a bond-slip degradation model of CFRP-concrete interface under the action of sulfate dry-wet cycle was proposed. The model prediction curve agreed well with the experimental curve. Compared with the experimental data, the prediction model can better reflect the trend of the interface bond-slip curve and the degradation pattern of the interface bond performance with the time of sulfate dry-wet cycles.