Bond-slip behaviors of BFRP-to-concrete interfaces exposed to wet/dry cycles in chloride environment

Fiber-reinforced polymer (FRP) has been employed as an alternative for strengthening and rehabilitation of deteriorated civil infrastructure, which can effectively prolong service-life and provide lower life-cycle costs than conventional materials. The present paper devotes attention to the influence of chloride environmental aging (wet/dry cycles) on the bond-slip characteristic of interface between basalt FRP (BFRP) sheet and concrete substrate. The four-point bending beam specimens were adopted to evaluate the durability of BFRP-concrete interfaces. The aging condition imposed on the BFRP beams was wet/dry cycles in salt water with 3.5% sodium chloride. After exposure, small beam tests were carried out to investigate the bonding behaviors of BFRP-concrete interfaces. The results indicate that the residual strength, ductility, and fracture energy of the bonded interfaces substantially decreased with increasing wet/dry cycles; the failure mode changed from the cohesive fracture of concrete in the ambient environment to the combined failure of BFRP fracture and adhesive debonding in aging condition; the effective bond length of BFRP where the tension force delivers from fiber fabric to cohesive interface was shortened under wet/dry cycles. Finally, a modified model was also proposed to predict the bond-slip relationship of the BFRP-concrete interface after wet/dry cycles exposure in a chloride-containing environment.