Experimental study on the durability of FRP bars reinforced concrete beams in simulated ocean environment

In this paper, the flexural performance of fiber-reinforced polymer (FRP) bars reinforced concrete (RC) beams after conditioning in a simulated seawater wet-dry cycling environment for 6, 9 and 12 months is experimentally investigated. Two types of FRP bars, i.e. basalt FRP (BFRP) bars and steel-FRP composite bars (SFCBs), are adopted. Steel bars are employed for comparison. During the conditioning, a constant load is coupled to the beams. A total of 24 simply supported beams are tested. In addition, microscopic damage to the conditioned BFRP bars is detected by scanning electron microscopy (SEM). The test results indicated that total corrosion was observed at the surface of the bottom longitudinal steel bars after a maximum exposure of 12 months. However, the degradation of the macro-mechanical properties of the steel bars RC beam was not distinct. The ultimate load of the BFRP bars RC beams after 6 months, 9 months and 12 months was reduced by 22%, 33% and 42%, respectively. The yield load and ultimate load of the SFCBs RC beams were reduced by a maximum of 18% and 38%, respectively. The SEM observations revealed that there were distinct damages at the outer layer of the BFRP bars after 12-month conditioning.