Effect of fiber section shape and volume fraction on the mechanical properties of steel-fiber reinforced concretes

This study presents the preparation of steel-fiber reinforced concretes (SFRCs) using straight navicular fibers with annular-sector-shaped sections and corrugated fiber with rectangular-shaped sections, respectively. The flexural and splitting tensile strengths of both the respective SFRCs increase with increasing fiber volume fraction, whereas their compressive strengths initially increase, then decrease, and then increase again. For the same fiber volume fraction, the mechanical properties of the navicular fiber-reinforced concrete are superior to those of the corrugated fiber-reinforced concretes. The introduction of steel fiber changes the failure mode of the plain concrete during bending from a typical brittle mode to a bimodal ductile failure mode. As compared to the corrugated fiber, the navicular fiber has stronger interface bonding to concrete and a higher friction resistance to fiber sliding and subsequent pullout. Furthermore, navicular fiber has a higher load-bearing capacity, which makes it more favorable for improving the mechanical properties of plain concrete.