Investigation on cracking resistance mechanism of basalt-polypropylene fiber reinforced concrete based on SEM test

In order to study the anti-crack mechanism of basalt-polypropylene fiber reinforced concrete (BPFRC), based on the restrained shrinkage test of BPFRC, the anti-crack enhancement mechanism of basalt fiber and polypropylene fiber was discussed through SEM microscopic test, and the sensitivity index of BPFRC's anti-crack performance was studied by combining grey relational theory and entropy weight method. The results show that basalt fiber has a significant inhibitory effect on the initiation and propagation of micro-cracks, and polypropylene fiber has a more obvious inhibitory effect on the propagation of macro-cracks. Mixing basalt fiber and polypropylene fiber into concrete can improve the pore structure of concrete matrix, reduce the initial defects of concrete matrix, enhance the density of the interface transition zone between aggregate and matrix, make concrete play a bridging role in different stages of stress deformation, and enhance the crack resistance of concrete more significantly. Grey relational theory combined with entropy weight method shows that the splitting tensile strength has the most significant influence on the crack resistance of BPFRC. This study can provide a new method for the sensitivity index analysis and crack resistance evaluation of concrete.