Durability of GFRP bar-reinforced seawater–sea sand concrete beams: Coupled effects of sustained loading and exposure to a chloride environment

Seawater-sea sand concrete (SWSSC) structures reinforced with glass fibre-reinforced polymer (GFRP) bars can favour the eco-construction of marine infrastructure. This study aimed to investigate the coupling effects of sustained loading and exposure to a chloride environment on the durability of GFRP bar-reinforced SWSSC beams. Two types of specimens were designed and tested: (1) GFRP bars covered with SWSSC to simulate GFRP bars within the beams and (2) GFRP bar-reinforced SWSSC beams. An accelerated ageing environment imposed on the specimens by wet-dry cycles in saline solution containing 3.5 % NaCl. The relationship between the degradation of the GFRP bars and conditioned beams were investigated. The results showed that SWSSC exhibited a better cooperative performance with GFRP bars than with conventional bars, resulting in good durability of GFRP bar-reinforced SWSSC beams exposed to chloride environments. Although the coupling conditions had a negative impact on the prestress losses of the conditioned beams, the ultimate flexural strength of the conditioned beams with over-reinforcement did not decrease significantly due to their failure controlled by the concrete. In addition, a re-correction model adopting the deterioration of GFRP bars was presented to es-timate the residual flexural strength of the conditioned beams exposed to the chloride environment. The results indicated that the strength deterioration of the GFRP bars by 36 % would trigger a 15 % degradation in the flexural strength of the conditioned beams.