Impact response of concrete reinforced with hybrid basalt-polypropylene fibers

The impact-resistance behaviour of concrete reinforced with hybrid basalt–polypropylene fibers (HBPRC) was experimentally investigated at strain rates of 101–102 s− 1, using a ϕ75 mm split-Hopkinson pressure bar. The strain-rate effect of the dynamic compressive strength, dynamic elastic modulus, critical strain, specific energy absorption and characteristic length of HBPRC was analyzed in detail. The results showed that all mechanical indices of HBPRC increased with increasing strain rate. The dynamic increase factor of compressive strength and elastic modulus increased linearly with the decimal logarithm of strain rate, and the critical strain and characteristic length increased linearly with strain rate. The addition of basalt fiber (BF) and polypropylene fiber (PF) yielded a significant increase in the strain-rate sensitivity of dynamic mechanical behaviour of HBPRC, while PF had a more significant effect compared to BF. Hybridization of BF and PF resulted in various influences on the strain-rate sensitivity of dynamic mechanical behaviour of HBPRC, but there was a significant positive correlation between the hybrid content of fibers and the strain-rate sensitivity of dynamic mechanical behaviour of HBPRC. The variation in specific energy absorption and characteristic length with strain rate and fiber content was consistent, and both could characterise the impact toughness of HBPRC.