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

Abstract

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 estimate 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.