Effects of simulated seawater on static and fatigue performance of GFRP bar–concrete bond

Abstract

Due to their excellent resistance to chloride ions, glass-fiber-reinforced polymer (GFRP) bars are employed to replace steel bars in seawater–sea-sand concrete (SWSSC). The performance of the concrete beams reinforced with GFRP bars depends on the bond between GFRP bars and SWSSC, which is significantly influenced by the marine environment and fatigue loading. Thus, the present study uses pullout tests to investigate the effects of simulated seawater on the static and fatigue properties of the GFRP bar–concrete bond. The impacts of the immersion time, environmental temperature, concrete type, and fatigue loading level are examined. The static interfacial bond strength and the corresponding slip of GFRP bar–SWSSC and GFRP bar–river-sand concrete (RSC) composites increase with the immersion time and the environmental temperature. Coupling the immersion environment and fatigue loading does not affect the failure mode of the GFRP bar–SWSSC and GFRP bar–RSC composites. Fatigue loading eliminates the defects in the interface between the GFRP bar and concrete, and the effects of eliminating the interfacial defects lessen with the immersion time and the environmental temperature. The fatigue load controls the performance degradation of the interfacial bond between the GFRP bar and concrete under coupling fatigue loading and immersion in simulated seawater. Meanwhile, there is no difference in the bond strength of the GFRP bar–RSC and GFRP bar–SWSSC composites under coupling fatigue loading and immersion in seawater. Nevertheless, the GFRP bar–SWSSC composite offers better static bond stiffness than the GFRP bar–RSC composite.