Research on impact toughness and crack propagation of basalt fiber reinforced concrete under SHPB splitting test

To cope with accidents such as explosion and high-speed impact, it is necessary to study the dynamic mechanical response of basalt fiber reinforced concrete (BFRC) under impact load. The dynamic splitting test of BFRC was conducted under different impact air pressures by Φ50 mm split Hopkinson pressure bar (SHPB) experimental platform and dynamic DIC acquisition system. The dynamic mechanical characteristics of BFRC under impact load were studied, focusing on analyzing the effects of different basalt fiber (BF) volume rates and average strain rates on its impact toughness. Meanwhile, the process of crack initiation, propagation, and penetration in BFRC during damage and failure was analyzed by DIC technique, the propagation speed and width of tensile crack were calculated by strain nephogram and pixel information. The results show that BFRC with 0.3% fiber content has the highest dynamic splitting tensile strength, dissipated energy and ultimate toughness. The strain rate effect of post-peak toughness is more obvious than that of pre-peak toughness. BF increases the impact toughness of concrete mainly by affecting the post-peak toughness. The crack propagation speed of BFRC is the slowest and the tensile crack width is the smallest with 0.3% fiber content, that is, the appropriate BF content (0.3%) can effectively reduce the damage degree of the matrix under the impact load and has the most obvious effect on the crack resistance and toughening of the matrix.