Exploration of Factors Reducing the Effect of Heating/Cooling Cycles on the Gas Permeability of a Mortar

Cement-based materials used as a sealing layer in compressed air energy storage (CAES) underground storage caverns have high requirements for gas permeability and resistance to thermal stress. This experimental study investigated factors reducing the initial gas permeability and the effect of thermal cycles on the gas permeability of mortar samples. The incorporation of silica fume, curing age of mortar samples, and confining pressure applied in the experiment were considered. Results of measurements of the real-time gas permeability of the mortar samples show that the gas permeability of mortar samples can be drastically reduced by replacing part of the cement with silica fume. After the samples were subjected to multiple heating–cooling cycles, gas permeability increased from the initial state. Extending the curing age and increasing the confining pressure improved the thermal stability of the mortar sample and reduced the effect of heating/cooling cycles on gas permeability.