Durability of glass fibre-reinforced polymer (GFRP) bars embedded in concrete under various environments. I: Experiments and analysis

This paper presents the tensile strength of glass fibre-reinforced polymer (GFRP) reinforcing bars embedded in concrete that is exposed to tap water, saline solutions and ambient humidity under accelerated conditions. These conditions were used to simulate the effect of river water, seawater or atmospheric moisture on the GFRP bars. In addition, the electrical impedance method was employed to evaluate the water content at different depths of a concrete cover under a variety of ambient humidity conditions. The effects of seawater, water-to-cement ratio (W/C) of the concrete cover, environmental humidity and cover depth were studied. The results revealed that the GFRP bars embedded in concrete exhibited a substantial strength loss when exposed to tap water or high ambient humidity. The degradation of concrete-wrapped GFRP bars immersed in saline solution could be different. This discrepancy is due to the variation of the degradation mechanism after exposure to chloride ions and is related to the cover depth. The depth of the concrete cover also had an evident influence on the durability results of GFRP bars subjected to various humid environments. Furthermore, reducing the W/C of the concrete cover had negative effects on the GFRP reinforcing bars.