Experimental investigation of physical and tensile mechanical properties of granite after different heating and cooling treatments

In this study a series of physical properties of granite were tested after different cooling treatments. Correspondingly, Brazilian splitting testing combined with acoustic emission (AE) testing was conducted on five groups of granite samples at different temperature levels, and scanning electron microscopy (SEM) was used to investigate the microstructure of granite. It was found that the P-wave velocity, hardness and thermal conductivity decreased with rising temperature. The tensile strength of granite was deteriorated by the action of temperature, and the progression of cracks was monitored using AE technology. The SEM results also indicated a significant increase in both the number and density of cracks in granite samples subjected to temperature variations compared to a naturally cooled group. In addition, after heating and cooling at different temperatures, samples with lower tensile strength exhibited rougher fracture surfaces, which were attributed to the generation of more thermal cracks during the heating and cooling processes. Moreover, a variation in the mechanisms for granite after temperature treatment is proposed.