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.

This work evaluates the influence of geometric properties, the length-to-width ratio, named Aspect Ratio, on curvatures in [θ − 90/θ]_T carbon/epoxy composite laminates at room temperature due to thermal residual stresses. A new method to determine experimentally thermal residual curvatures in composites laminates by defining small-length increments on the surface of deformed plate has been exposed. [–45₄/45₄]_T was considered to obtain a simple analytical expression of twisting curvature. A new way to determine transverse coefficient of thermal expansion α₂ is proposed in squared laminates based on experimental values of twisting curvatures of [–45₄/45₄]_T laminates.