Effect of heat-treatment on the dynamic compressive strength of Longyou sandstone

• Investigate the effect of thermal-treatment on rock dynamic compression
• Used the X-ray Micro-CT scan to quantify the damage of sandstone samples
• The dynamic strength of rock increases with the loading rate.
• The dynamic strength of rock decreases with the heat-treatment temperature.
• A model is developed to consider the rate and thermal effects on dynamic strength.

Temperature plays an important role in many rock engineering practices. The increase or decrease of temperature induces the damage characterized by cracks/voids in the rock and thus reduces its strength. Therefore it is essential to quantify the damage induced by the heat-treatment and establish its correlation to the mechanical properties of rocks. In this study, X-ray Micro-computed tomography (CT), a non-destructive observation technique was utilized to quantify the damage induced by the heat-treatment. Using CT images, the damage variables were measured for Longyou sandstone (LS) at three heat-treatment temperatures, 250 °C, 450 °C, and 600 °C, and room temperature of 25 °C. The dynamic compressive strength of LS was then obtained by a modified split Hopkinson pressure bar system with the loading rate from 102 to 104 GPa/s. An empirical equation to quantify the correlation between the damage variable and the dynamic compressive strength was established from the experimental data.