Experimental study on thermophysical properties of clay after high temperature

Thermophysical properties are among the most basic properties of soil and play a key role in the efficient utilization of energy and heat insulation performance. Though several researchers have studied the influence of temperature on thermophysical properties, the scope of the temperature is usually below 100 °C, and the relationship between thermophysical properties and mass loss caused by high temperature has not been investigated in detail. In this paper, the effect of high temperatures (up to 800 °C) upon the thermophysical properties of clay is investigated and the relationship between thermal parameters and mass loss is researched via laboratory test. The test results indicate that thermal conductivity and specific heat decrease exponentially as temperatures rise, and thermal diffusivity that fluctuates between 0.3 mm2/s and 1.2 mm2/s exhibits a certain degree of volatility with temperature. When the temperature rises, the water dissipates, the clay splits, and the organics carbonize and sublimate. All of these physical-chemical changes make the water content decrease and porosity increase, eventually altering the thermal parameters of clay. Furthermore, thermal conductivity displays a good linearity with mass loss and a negative exponent with porosity. The results obtained in this paper will be good for predicting the thermophysical properties of clay when exposed to high temperature.