Impact Resistance and Flexural Performance Properties of Hybrid Fiber-Reinforced Cement Mortar Containing Steel and Carbon Fibers

Fiber-reinforced cement mortar (FRCM) has been widely used since it has many advantages compared to plain mortar (PM), and various fibers are highly applicable as repair and reinforcement materials for concrete. In the present paper, an experimental study was planned to investigate the properties, such as flexural performance (flexural strength and toughness), compressive strength, and impact resistance of mono fiber-reinforced cement mortar (MFRCM) containing only steel fiber (SF) or carbon fiber (CF), as well as hybrid fiber-reinforced cement mortar (HyFRCM) containing different combinations of SF and CF. The fiber content was used in five levels (0.0, 0.25, 0.5, 0.75, and 1.0%) at a total volume fraction of 1.0% by volume. The results show that HyFRCM containing 0.75% SF and 0.25% CF improved compressive strength, flexural strength, and impact resistance compared to MFRCM and other HyFRCM, resulting in a synergistic effect of hybrid reinforced fibers. It is noted that, in the case of HyFRCM containing 0.5% SF and 0.5% CF, the flexural strength was slightly lower, but the highest flexural toughness was obtained, which led us to judge that the result shown in this investigation can be the optimal fiber combination to improve toughness and energy absorption capacity.