Investigation of Residual Strength of GFRP Bar Reinforced Concrete Beams with Recycled Materials Under Elevated Temperature

This research investigates reinforced concrete beams with three groups of Glass Fiber Reinforced Polymer (GFRP) bar, Sand-blasted Glass Fiber Reinforced Polymer (SGFRP) bar and steel bar with concrete containing recycled materials with different concrete mix design before and after applying elevated temperature. The concrete mix designs include replacing glass powder and micro-silica with a part of concrete cement and replacing waste crumb rubber and glass crumb with a part of fine and coarse concrete aggregate. The beams were subjected to high temperature up to 600 °C in an electric furnace, and then subjected to the flexural strength test. The results showed that applying elevated temperature to beams reinforced with composite bars caused a sharp drop in flexural strength. The beam exposed to high temperature containing glass powder, coarse rubber and micro-silica had 2.2 times more flexural strength than the reference beam exposed to high temperature, and the beam not exposed to high temperature in this mix had 36% more flexural strength and 54% more ductility than the reference beam that was not exposed to high temperature. The beam with SGFRP bar with sand coating showed higher flexural strength after applying elevated temperature than the beam with GFRP bar with normal surface. In general, the replacement of recycled materials in the concrete improved the performance of the beams against elevated temperature compared to the beams with normal concrete.