Experimental and numerical simulation study on the dynamic behavior of basalt-polypropylene fibers reinforced coral aggregate concrete

This study investigates the failure mode, dynamic compressive strength, strain rate effect and critical strain of basalt-polypropylene fiber-reinforced coral concrete (BPRCAC) under impact load using a 75 mm diameter split Hopkinson pressure bar (SHPB). The Holmquist-Johnson-Cook (HJC) model is modified to obtain parameters such as strain rate effect and strength based on the test results, utilizing LS-DYNA for numerical simulation analysis. The results indicated that the dynamic compressive strength and critical strain of BPRCAC significantly respond to the strain rate, increasing with the strain rate. A relationship between the dynamic increase factor (DIF) and the strain rate of BPRCAC is developed, showing that the DIF increases linearly with the decimal logarithm of the strain rate. However, the critical strain of BPRCAC increases linearly with the strain rate. The addition of basalt fiber (BF) and polypropylene fiber (PF) improves the strain rate sensitivity of the dynamic compressive strength, with increases of 19.21 %, 7.37 %, 22.60 %, and 11.37 % observed for BCAC-0.1, PCAC0.1, BPCAC-0.1, and BPCAC-0.2, respectively, compared to CAC at a strain rate of 133 -143 s- 1. The combined content of BF and PF has a more significant effect on the strain rate sensitivity of the critical strain, with BPCAC0.2 exhibiting a critical strain 50.79 %-74.42 % higher than that of the other groups compared to CAC. The stress-strain curves and failure modes of the specimens simulated by LS-DYNA agree with the experimental results, verifying the applicability of the improved HJC model to BPRCAC.