Thermal effect on wave velocity of sandstone after high-temperature treatment: a review

Variations in wave velocity and porosity of sandstone after high-temperature treatment are investigated. The results for normalized wave velocity and porosity show that 400 degrees C is the critical threshold temperature of sandstone. Below 200 degrees C, porosity increases slowly as the treatment temperature increases, while wave velocity gradually decreases. When the temperature is higher than 400 degrees C, porosity quickly increases, and wave velocity sharply decreases. The room temperature-200 degrees C and 200-400 degrees C temperature ranges correspond to the undamaged state and the microdamage state, respectively.