Flexural Toughening of Hooked-End Steel Fibers Reinforced Mortars

This paper investigated the effect of hooked-end steel fiber at varying fiber content on the flexural toughening of fiber reinforced cement mortars (FRCM) by using three-point bending tests. In particular, to preserve the mortar workability, three low weight fractions (0.3%, 0.5% and 0.7%) and two cement matrices (M10 and M15) were investigated. The results showed that the mechanical bending behavior of the FRCM increases significantly at increasing fiber content and cement plaster matrix. An important aspect that has been addressed is how the flexural toughening is varied at varying fiber content and the type of matrix. Especially, all composite mortars exhibited a toughness index (TI) in the range of 10–45, indicating a suitable strengthening and toughening effect supplied by the hooked-end fiber addition. The best TI value, equal to 44, was experienced for the M10-D7 batch characterized by 0.7 wt.% of hooked-end steel fibers and an M10 cement matrix. Furthermore, unlike unreinforced concrete where brittle and unexpected failure occurs dominated by a sudden and catastrophic propagation of tensile cracks, the FRCM samples exhibited a ductile behavior with a marked residual post-crack resistance even for composites mortars with low metal fiber content.