Collaborative tensile performance and fracture behavior of rock-concrete composite material under Brazilian splitting

The mechanical and fracture characteristics of rock-concrete composite (RCC) have always been a key focus in rock mass engineering. To investigate the collaborative tensile properties and failure characteristics of RCC, composite disc specimens were prepared by using red sandstone and concrete. A series of Brazilian splitting tests were performed to examine the influence of volume proportion of composite material on the tensile properties and fracture behaviors of RCC. It is indicated that the decreasing volume proportion of rock decreases the total brittleness of RCC, but increases the ability of absorbing energy, further resulting in increased deformation. Meanwhile, the tensile strength decreases and presents greater discreteness with increasing concrete proportion, and tensile cracks gradually decrease accompanied by the increase of shear cracks. In addition, cracks with significant energy release occur in red sandstone, while the cracks appeared in concrete have small energy release. The theoretical analysis and experimental results of crack development are consistent, indicating that tensile fracture initiates in concrete and shifts from the disc end to the center with increasing concrete volume. The research results can provide reference for the analysis of the collaborative tensile bearing characteristics and failure mechanism of RCC in related rock engineering.