Experimental Study and New Model for Flexural Parameters of Steel–PVA High-Performance Fiber–Reinforced Concrete

The flexural properties of high-performance concrete (HPC) can be enhanced by mixing two fibers with appropriate volume contents. Four-point bending tests were conducted on 48 beams to investigate the flexural behavior of steel–polyvinyl alcohol (PVA) fiber–reinforced HPC. The effects of the volume content and hybrid ratio of fibers on the flexural parameters such as strength and toughness are discussed. The synergistic effect of the two fibers reinforcing the HPC was analyzed quantitatively. The reinforcing index (RIv) considering the elastic modulus and tensile strength of fibers was used to analyze the flexural parameters of steel–PVA fiber–reinforced HPC. The results indicate that addition of steel fiber or PVA fiber individually can improve the flexural properties of HPC. In steel–PVA fiber–reinforced HPC, the addition of steel fiber enhances the peak strength and toughness, and the addition of PVA fiber improves the first peak strength and deformation capacity. With 2% total fiber volume content, the best synergistic effect was achieved at 1% volume content of both steel and PVA fibers. The new model fits well with the experimental results and can be used for the ratio design of steel–PVA fiber–reinforced HPC.