Thermal properties of sandstone after treatment at high temperature

This paper reports the variations of thermal conductivity, thermal diffusivity and heat capacity of sandstone after high-temperature heating. Experiments were carried out to test the thermal properties of sandstone which had been heated at temperatures ranging from room temperature to 900 °C in a furnace. Temperature has a significant impact on the thermal conductivity, thermal diffusivity and heat capacity of sandstone, which is closely related to the loss of water and damage of structure caused by thermal reactions. The results indicate four phases in the variation of thermal parameters with temperature: from room temperature to 200 °C, 200–400 °C, 400–600 °C, and above 600 °C. The first and second phases correspond to the vaporization-escaping interval of adhered water, combined water and structural water. Between 400–600 °C, especially from 500–600 °C, the minerals in sandstone has thermal reactions, which are demonstrated as porosity increase, reduction of conductivity and diffusivity, and change of heat capacity.