Investigation of ductility behavior of polypropylene fiber reinforced concrete beams

Fibers are widely used in structural concrete members in recent years, because of its ability in improving many parameters of concrete. Present research is attempted to employ a balance among the three factors (cost, quality, and construction time). This study aims to investigate the methods of improving ductility behavior of polypropylene (PP) fiber reinforced concrete beams. This will be done through constructing a conventional high strength concrete that have ability to gain its strength quickly after the casting, by increasing the fine aggregate and fine additive materials which complementing by decreasing the coarse particles. In order to improve the mechanical properties of both fresh concrete in term of slump and fiber dispersion efficiency, furthermore in hardened concrete in term of displacement, and robust multiple cracking behavior under tensile action tests are done. Several concrete beams reinforced with different percentages of PP fiber (0.5, 1.0, 1.5 %) are constructed with different number of conventional longitudinal steel reinforcement and compared with control beams. The clear dimensions of the beams used in this investigation are 150 X 150 X 850 mm. In general, the addition of PP fiber improved the mechanical properties of concrete. As well as the more ductile behavior is found in beams with PP fibers compared with normal concrete beam, so increase of the volume fraction is giving better ductility. Where the ductility of beam 1.5 PP-2R has improved by 53 %. Key Words: Polypropylene, fiber-reinforced beams, ductility