Experimental study on the bond behavior between corroded rebar and concrete under dual action of FRP confinement and sustained loading

The corrosion of reinforcing steel bars (rebar) in reinforced concrete (RC) is the main cause of the degradation of interfacial bond behavior between rebar and concrete, which can further induce the degradation of structural performance. In this paper, the bond behavior between corroded rebar and concrete was experimentally studied focusing on the coupling effects of lateral confinement and sustained load for the first time. Continuous and uniform confining pressures were imposed on the corroded rebars via fiber reinforced polymer (FRP) and sustained loads were applied to the corroded rebar by a self-developed loading device. The effects of corrosion ratio, sustained load and lateral confinement on the bond behavior were tested and analyzed. The test results demonstrated that FRP lateral confinement could effectively restrain the corrosion rate of rebar and thus significantly improved the bond performance; moreover, the dual action of FRP lateral confinement and sustained load could significantly enhance the interfacial bond strength and ductility due to their great contribution to the prevention of corrosion expansion. However, without FRP lateral confinement, the interfacial bond strength and ductility would be weakened by sustained load.