Development of a Proper Mix-Design for Impact Loading of Deflection Hardening Hybrid Fiber Reinforced Concrete

This study aims to develop a low-cost Hybrid Fiber Reinforced Concrete (HyFRC) that exhibits deflection hardening behavior under bending and has high energy absorption capacity under impact loading by determining proper combination of steel and polyvinyl alcohol (PVA) fibers. More than forty mixtures were prepared including two mixtures of conventional concrete, six mixtures of Engineered Cementitious Composites (ECC), and thirty-six mixtures of HyFRC. The design parameters were chosen as fly ash to cement ratio (1.2, 1.7 and 2.2), steel fiber type and amount (0.5%, 0.75%, and 1.25% by volume), PVA fiber amount (0.25% and 0.50% by volume), and maximum aggregate size (Dmax) of 8 mm and 16 mm. Several tests were carried out on fresh and hardened specimens such as bending, compression, and low-velocity flexural impact loading. Based on the results, it is found that the mixture with 0.75% steel fiber and 0.25% PVA showed the best performance for the aim of the study.