Experimental study on the behavior of polypropylene fiber-reinforced concrete beams

This research aimed to analyze the behavior of concrete beams reinforced with polypropylene fibers. This type of reinforcement has been increasingly used in construction to improve the tensile properties of concrete, mitigate the propagation of microcracks due to shrinkage, enhance impact capacity, and extend the durability of concrete structures. An experimental study was conducted on twelve concrete beams with dimensions of 150 x 150 x 600 mm, reinforced with polypropylene fibers, divided into four groups: 0.35%, 0.45%, and 0.55% fibers/m³ of concrete, along with a reference group without fibers. Four-point flexural tests were performed following the recommendations of the NBR 12142 (ABNT, 2010) to evaluate the influence of the fibers on the contribution to tensile strength in flexure. The results showed that the beams reinforced with 0.35% fibers/m³ exhibited the best performance, with a significant increase in strength compared to the other groups, with and without fiber reinforcement. All fiber-reinforced groups showed a shift from brittle to ductile behavior. Additionally, the beams with 0.55% fiber content demonstrated greater ductility but less contribution to tensile strength.