Fire is reflected as one of the most serious possible risks for buildings and constructions. The main objective of this research is to investigate the effect on the performance of beams reinforced concrete under and without fire conditions by adding waste polypropylene fibers (WPPF) with two variable values of volume fraction. Six beams with different volume fraction of WPPF ratio were tested to study the behavior of the beams when exposed and not exposed to fire conditions. Three of these

more »

... were prepared with volume fraction of WPPF ratios 0%, 0.5%, and 1% to test under two-point loads without exposure to fire, while the other beams were prepared with same conditions to test after exposure to fire. The results showed that the reinforced concrete beams without fibers suffered significant reduction in overall performance and mechanical properties, when subjected to fire for enough time to reach elevated temperatures (400 C 0 ). Both 0.5% and 1% of WPPF ratios didn't affect the flexural capacity before the fire, however, reduction in compressive strength occurred. On the other hand, the fiber improved the tensile strength and the first cracking load, and also reduced the loss in compression strength after the fire. Finally, the recommended optimal ratio of WPPF is not more than 0.5%.