Study on the tensile properties of basalt fiber reinforced concrete under impact: experimental and theoretical analysis

Basalt fiber (BF) can significantly improve the dynamic properties of concrete. However, the underlying mechanism of the effect on the dynamic splitting tensile properties of concrete by comprehensively considering BF content and BF length has not been fully clarified. Under such a background, this study aimed to carry out an orthogonal experiment on the dynamic splitting tensile properties of basalt fiber reinforced concrete (BFRC) by taking into account different fiber contents and lengths using the split Hopkinson pressure bar equipment. The research results indicate that addition of BF improves the dynamic splitting tensile strength and the integrity of concrete after failure. In addition, the sensitivity of the dynamic increase factor of concrete to strain rate shows a continuously increasing trend as BF content increases, but an upward trend first followed by a downward trend with the increase of BF length. Based on the combined results, the optimal fiber content and length were determined to be 0.2% and 6 mm, respectively. Then, combined with high-speed camera and scanning electron microscopy, the failure mechanism of BFRC was deeply revealed. It is found that the reinforcing effect of BF on concrete is mainly reflected as the pull-out failure at low strain rates and the pull-apart failure at high strain rates. Moreover, BF can change the development mode of cracks during the failure process by inhibiting the development of shear failure zone, thereby playing its cracking resistant role. Finally, the K&C model was modified based on the experimental data to make it adapt to BFRC.