Abstract:
To explore the influence of machine-made sand (MMS) and polyvinyl alcohol (PVA) fibers on the static and dynamic mechanical properties of high-strength concrete (HSC), this study conducted static axial compression and Split Hopkinson Pressure Bar (SHPB) impact compression tests across a range of MMS replacement rates (0%~100%) and PVA fiber volume fractions (0%~0.6%). The experimental results demonstrate that the most significant synergistic reinforcement effect occurs at an MMS replacement rate of 50% and a PVA fiber fraction of 0.3%. Under these conditions, the descending branch of the static stress-strain curve becomes notably more gradual, which significantly mitigates the brittle failure characteristics inherent in high-strength concrete. A static compressive constitutive model developed from the experimental data yielded a goodness-of-fit exceeding 0.925, accurately characterizing the damage evolution law of the material under axial compressive loading. Furthermore, impact tests confirmed that the material exhibits a pronounced strain rate enhancement effect. Compared to components with single additives, the hybrid incorporation of MMS and PVA fibers significantly enhances the deformation coordination capacity and residual stability of HSC under dynamic loading through the coupled effects of mechanical interlocking and fiber bridging mechanisms.