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There is a continued process to implement innovative materials to enhance the sustainability and durability of the built infrastructure. Technologies developed over the last two decades have facilitated the use of glass fiber reinforced polymer (GFRP) composites as internal reinforcement bars (rebars) for concrete structures, which have proven to be an alternative to traditional steel reinforcement due to significant advantages, such as magnetic transparency and, most importantly, corrosion resistance, equating to durability and structural life extension. This study evaluates the durability of three different available and most commonly used GFRP rebar types, based on exposure to aggressive environments, such as those experienced in coastal areas. For that, the specimens were expose to high pH seawater solution (that simulates the alkalinity of the concrete exposed to seawater), at 60 ºC for different periods of time: 45, 90, and 180 days. The durability of these GFRP rebars was assessed by testing four different physio-mechanical properties, including: tensile strength, elastic modulus, and transverse and horizontal shear strength. Preliminary results show that the resilience of the GFRP rebars after being exposed to high pH seawater at high temperature, varies considerably among the three different types. The tensile strength was the most affected physio-mechanical property.

Increased traffic in combination with growing environmental impacts have led to the accelerated degradation of built infrastructure. In reinforced concrete structures, the corrosion of steel reinforcement is the predominant cause of deterioration. Thus, over the last years the use of glass fiber reinforced polymer (GFRP) composites as internal reinforcement bars (rebars) for concrete structures has been evaluated, and has been proved to be a viable alternative to traditional steel reinforcement mainly due to its tensile strength and non-corrosive nature. However, thus far, the GFRP rebar market is diverse and manufacturers around the world produce GFRP rebar types with different surface enhancements to improve the bond to concrete characteristics. In this study, the bond performance of three dissimilar GFRP rebar types (sand coated, helically grooved and with surface lugs) was evaluated over time in seawater environments, with a focus on the bond strength. Accordingly, specimens were exposed to seawater in circulating chambers at three different temperatures (23 °C, 40 °C and 60 °C) for multiple time periods (60 and 120 days). To evaluate the bond performance, pullout tests were conducted according to ASTM D7913. The results showed that the bond strength varied with the surface enhancement features. However, the bond strength did not vary significantly with exposure time and temperature for all three evaluated rebar types.

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