Experimental and numerical investigation on the mechanical properties of sandstone under microwave irradiation

To investigate the mechanical properties of sandstone under microwave radiation, an industrial microwave oven was used to explore the influence of the heating characteristics on the compressive and tensile strengths of the sandstone under microwave irradiation. Besides, the electromagnetic evolution in the microwave oven and the sandstone’s temperature and electric field were analyzed. The microscopic mechanism was revealed by the thermogravimetric analysis and scanning electron microscope test. The results show that, with increasing the irradiation time and microwave power, the maximum surface temperature of the sandstone is increased, the compressive strengths and tensile strengths of the sandstone are increased first and then decreased, and the P-wave velocity is decreased. The microwave irradiation with low power and short time causes water loss in the sandstone, a reduction of the lubrication effect between particles and an increase of the bonding effect, which leads to the increase of the sandstone’s strength. However, microwave irradiation with high power and long time creates a lot of interior microcracks for the sandstone, which decreases the sandstone’s strength. Finally, numerical simulations reveal that the mechanical properties of the sandstone under microwave irradiation are mainly influenced by the thermal stress due to the uneven temperature.