Durability of GFRP-RC Square Columns in Severe Marine Environment

Abstract

This paper reports on an investigation of the axial compression behavior of glass fiber reinforced polymer (GFRP)-reinforced concrete (RC) square columns after immersing in simulated severe marine environments. Four laboratory-scale GFRP-RC square columns (300 mm width and 1000 mm height) were reinforced longitudinally with GFRP bars and transversely with GFRP square spirals. Two columns (set as conditioned specimens) were continuously immersed in a simulated marine environment (saline solution) at high temperature (heat waves—60 °C) for 365 days before testing under concentric loading. The remaining two columns were kept at room temperature (set as unconditioned specimens). The results revealed that due to conditioning, the concrete gained strength, causing an enhancement in the axial capacity of tested columns by about 23.5% compared to their control counterparts, on average. Moreover, the GFRP bars and spirals did not show any degradation in their material, as illustrated in SEM images. The optical microscopy (OM) results showed that no debonding between concrete and bars was observed. The effect of increasing the longitudinal reinforcement ratio on the axial carrying capacity was limited, and almost neglected; however, its effect on post-peak response was significantly pronounced.