Interlaminar shear capacity of thermally damaged GFRP bars under alkaline concrete environment

The paper investigated the effect of alkaline concrete environment on thermally damaged glass fiber reinforced polymer (GFRP) reinforcing bars through an accelerated aging test in alkaline solution. In the experimental test, the GRFP bar specimens were exposed to high temperatures and then immersed in alkaline solution with a pH of 12.6 presenting the similar alkalinity of concrete. Other specimens, which were unexposed to high temperatures, were also immersed in the alkaline solution for the same period of time in order to compare the performance changes in inter-laminar shear strength and stiffness capacities (ILSS and ILSSf). From the test results, the bar specimens which were thermally damaged by high temperature showed more degradation in ILSS than the thermally undamaged ones; rapid performance degradation occurred for longer immersion periods. Analysis of scanning electron microscope images showed that the fine cracks on the surface and resin matrix damage developed during exposure to high temperature led to accelerate alkali penetration, thereby resulting in rapid performance degradation.