The influence of temperature and moisture content on sandstone thermal conductivity from a case using the artificial ground freezing(AGF) method

The thermal conductivity (TC) of rocks is influenced by a number of environmental factors including temperature, moisture content, and pressure. A series of experiments are presented in this work to address the influence of temperature both sides of the freezing point 0 °C as well as moisture content on sandstone TC values. All of the specimens discussed were collected from a coal mine shaft excavation using the artificial ground freezing (AGF) method. Thus, TC values of 32 pairs of medium grained sandstone and 21 pairs of coarse grained sandstone specimens were measured at temperatures ranging between −30 °C and 50 °C. The results show that TC values tend to increase as temperature decreases regardless of whether specimens are dry or water-saturated. It is also the case, however, that water-saturated specimens commonly have higher TC values than their dried counterparts at different target temperatures, especially at the range of between 5 °C and − 10 °C, while TC values of water-saturated specimens exhibited rapid increases. This phenomena also shows a good agreement with the deflection zone presented in Raman spectral peak values, clear evidence for the water-ice phase transition period.