Tensile strength retention of glass fibre-reinforced stirrups subjected to aggressive solutions: effect of environmental condition, stirrup shape and stirrup diameter

The aim of this study was to examine how the tensile strength of glass fibre reinforced polymer stirrups is affected by different types of solutions, including alkaline, seawater, tap water, and acidic solutions. The study involved the production and testing of 260 stirrups in two different shapes (L and U) with diameters of 6 and 8 mm. The stirrups were immersed in different solutions for a period of 9 months at different temperatures (25, 40, and 60 °C). The findings indicated that the alkaline solution was the most aggressive environment, resulting in a maximum reduction of 92% in tensile strength after 9 months at 60 °C. Seawater and acidic solutions were the second and third most aggressive environments, causing maximum tensile strength reductions of 34 and 22% respectively, after 9 months at 60 °C. On the other hand, tap water was found to be the least aggressive environment, causing a maximum tensile strength reduction of 20% after 9 months at 60 °C. Furthermore, the study observed that the L-shaped stirrups exhibited slightly superior performance compared to the U-shaped stirrups. However, the diameter of the stirrups was found to be a negligible factor.