Effect of fiber type, shape and volume fraction on mechanical and flexural properties of concrete

Abstract

An experimental work was herein presented focusing the effect of different type, shape and volume fraction of fibers on the hardened properties of concrete including compressive, splitting tensile and flexural strengths at 7 and 28 curing days. A control concrete mixture including no fiber was prepared and six fiber-reinforced concrete (FRC) mixtures were designed by using two different fiber types and volume fractions. Two types of steel fibers having different shapes (short straight and long hooked end) and polypropylene fiber were used with the volume fraction of 0.4% and 0.8%. The load-deflection curves and toughness of the specimens were analyzed based on ASTM C1609. The results showed that the utilization of short straight steel fibers with 0.8% volume fraction was most efficient at enhancing the compressive strength with 9.98% while the use of 0.8% long hooked end steel fibers provided better splitting tensile and flexural strengths with 33.33% and 30.35%, respectively, compared to specimen with no fiber at 28 curing day. Besides, the long hooked end steel fibers with the volume fraction of 0.8% contributed to an excellent deflection hardening behavior resulting in higher load deflection capacity and higher toughness values at peak load, L/600 and L/150. On the other hand, with incorporation of polypropylene fiber, all strength values decreased regardless of the volume fraction and curing days.