Research on compressive impact dynamic behavior and constitutive model of polypropylene fiber reinforced concrete

The latest experimental studies indicate that polypropylene fiber is able to remarkably enhance the ability of concrete to resist impact loading and crack. This paper further studies the dynamic behavior and constitutive model of polypropylene fiber reinforced concrete (PFRC) at high strain rate. PFRC specimens with various polypropylene fiber content (0, 0.8, 1.2, 1.6, 2.0, 5.0 kg/m3) are tested by utilizing the Split Hopkinson Pressure Bar (SHPB). Both the quasi-static tests and the SHPB tests were performed to study the effect of fiber content, strain rate and water-cement (w/c) ratio on the dynamic mechanical properties of PFRC. Test results indicate that the dynamic mechanical properties of PFRC such as dynamic strength, dynamic increase factor, peak and ultimate strain, peak and ultimate toughness, are positively affected by strain rate. Polypropylene fiber can improve the impact toughness and crack resistance of concrete and it is more suitable for concrete material with a higher w/c ratio. Finally, the experimental stress-strain curves obtained in SHPB test were fitted by a damage dynamic constitutive model of PFRC on the basis of ZWT constitutive model. The great fitting results prove that the modified model can well describe the dynamic behavior of PFRC.