Experimental study on bond behavior between epoxy-coated reinforcement (ECR) and seawater sea-sand concrete (SSC) under FRP-steel confinement

Abstract

This paper investigates the bond behavior between epoxy-coated reinforcement (ECR) and seawater sea-sand concrete (SSC) under dual confinement from fiber-reinforced polymer (FRP) and steel stirrups. The effects of various variables on failure modes, bond-slip curves and bond strengths were comprehensively discussed, including internal reinforcement type, concrete type, concrete cover, confinement type and confinement level. Test results show that the use of seawater and sea-sand in concrete is beneficial for the enhancement of bond strength compared with normal concrete, but the bond strength of SSC specimens with embedded ECR is found to be smaller than the counterparts with carbon steel reinforcement (CSR) due to the external epoxy coating on the bar surface. Besides, the bond strength is positively related to the concrete cover and confinement level regardless of other parameters. Finally, a new ultimate bond strength model considering the contribution of FRP-steel confinement is proposed based on theoretical analysis and good agreement between test results and theoretical predictions is achieved by the proposed model.