Mechanical performance study of basalt-polyethylene fiber reinforced concrete under dynamic compressive loading

In order to enhance concrete's impact resistance, this study investigates the effects of single basalt fiber and basalt-polyethylene hybrid fiber on concrete through split Hopkinson pressure bar (SHPB) tests, emphasizing their significance in engineering applications. A comparative analysis of the failure modes, dynamic compressive strength, dynamic compressive toughness, and dynamic growth factor of specimens was conducted under different strain rates and polyethylene fiber volume fractions. The study considered concrete damage, strain rate effect, and the toughening effect of fibers, introducing the damage factor, and establishing a dynamic damage constitutive model for fiber-reinforced concrete. The results showed that basalt-polyethylene fiber reinforced concrete (BPFRC) exhibited better impact resistance and deformation capability. There were improvements observed in dynamic compressive strength, dynamic compressive toughness, and dynamic growth factor. The addition of basalt fiber (BF) and polyethylene fiber (PE) played a buffering role in inhibiting crack propagation and slowing down the damage process. The optimum PE volume fraction for dynamic compressive strength was 0.1% at a strain rate of 60 s-1, 0.15% at a strain rate of 95 s- 1, and 0.05% at a strain rate of 120 s- 1, all with a BF volume fraction of 0.25%. The optimum fiber volume fractions for dynamic compressive toughness and dynamic peak toughness were consistent, both at 0.25% BF and 0.1% PE. The established dynamic damage constitutive model for fiber-reinforced concrete can effectively describe the impact resistance performance of BPFRC, and the experimental curves fit well with the constitutive curves. Furthermore, it was observed that BF acted as macrofibers, bridging to restrain the post-hardening cracking of concrete, while PE acted as microfibers, inhibiting the propagation of plastic cracks, reducing internal defects in concrete, and enhancing the ductility and toughness of concrete. Consequently, BPFRC holds significant potential value in engineering applications.