Behaviour of Geopolymer Concrete Two-Way Slabs Reinforced by FRP Bars After Exposure to Elevated Temperatures

This study investigates the residual mechanical behaviour of geopolymer concrete (GC) slabs reinforced with fibre-reinforced polymer (FRP) bars after exposure to elevated temperatures. For the aim of the study, a comprehensive experimental study was implemented for FRP-reinforced two-way GC slabs that were exposed to four different temperature levels by considering the reinforcement material, reinforcement percentage, type of concrete and thickness of the concrete cover. The residual mechanical properties, ultimate slab strength and deflection performance were all examined. As a result of the study, similar performance was observed for the slabs exposed to 350 degrees C and ambient temperature, while a significant difference was seen for the specimens exposed to 550 and 650 degrees C. The effects of several parameters on the high-temperature performance of FRP-reinforced GC slabs were examined in detail. The parametric study results indicated that slabs reinforced with basalt fibre-reinforced polymer (BFRP) bars have a higher elevated temperature resistance than slabs strengthened with glass fibre-reinforced polymer (GFRP) bars, even for the same ratio of reinforcement. Moreover, the results showed that upon increasing the reinforcement ratio, a higher punching shear capacity and lower deflections were obtained at both ambient and elevated temperatures. Additionally, the results indicated that the high-temperature resistance of GC slabs was better than the high-temperature resistance of ordinary concrete (OC) slabs. Moreover, the thickness of the concrete cover showed a significant impact on the high-temperature behaviour of FRP-reinforced concrete slabs. The slabs with a higher cover thickness exhibited better performance at elevated temperatures.