Effect of temperature on thermal conductivity of lateritic clays over a wide temperature range

The temperature dependence of the relationship between thermal conductivity and saturation of lateritic clays is more complex than that of other soils. This paper reports sample-scale measurements of thermal conductivity of two lateritic clays with aggregates and dual-porosity at different saturations and temperatures. Test results indicate that the thermal conductivity increases with increasing temperature. The effects of the latent heat transfer (LHT) of vapor on the thermal conductivity were more pronounced at intermediate saturations and temperatures above 60 °C. The thermal conductivity resulting from the LHT of vapor has obvious peak value with saturation, and its peak value and corresponding saturation are related to the clay content. The difference in the thermal conductivity from the LHT of vapor between two clays at a given temperature is due to the effect of the microstructure. The mercury intrusion porosimetry (MIP) tests were also performed to observe the pore-size distribution (PSD) of two lateritic clays, which can explain the difference in the temperature effect on thermal conductivity. The inter-particle contact heat transfer (IPCHT) model provides good agreement with test data at temperatures ranging from 5 to 90 °C for two lateritic clays. The soil-water retention curves play an important role in predicting the thermal conductivity by the IPCHT model, which can be further improved by better consideration of the microstructure and phase configuration.