Effect of Bound Water Content in Red Clay on Its Thermal Conductivity

Taking the 2 types red clay in Guangxi area as the research object, through the isothermal adsorption test, the type and content of the adsorbed bound water in the red clay were determined, and the nature of the difference in the amount of adsorbed bound water in the two red clays was explained from the microscopic perspective by the mercury-pressure test. Based on this, the thermal conductivity of two kinds of red clay samples under different water contents was measured by the thermal probe method, and the influence of bound water content on the thermal conductivity of red day was discussed. The results showed that the total amount of adsorbed bound water in Guilin red clay and Liuzhou red clay was 22.417% and 10.957%, respectively, and the former one was about twice as much as the latter one, mainly due to the difference in mineral composition of the two red clays. The red clay in Guilin has a higher content of small pores compared to that in Liuzhou, resulting in a higher porosity and greater specific surface area, which endows it with a stronger capacity to adsorb and bind water. The thermal conductivity of the two red clays increased with the increase of the bound water content. The effect of bound water content on thermal conductivity can be attributed to both the bound water film and the "liquid bridge" effect in the soil.