Estimating thermal conductivities of highly-cemented Edmonton clay at subzero temperatures

Effective thermal conductivity (λ; the ability of a material to conduct heat) of cemented clay from deep soil mixing (defined as soilcrete) is critical for assessing the durability and stability of foundations in cold regions, but research on the thermal properties of soilcrete in cold regions is limited. The present study was aimed at estimating λ of soilcrete specimens prepared in the lab at subzero temperatures ranging from −2 to −30°C using experimental methods and empirical equations. A device that can implement a radial heat flow was developed in the present study. Steady-state (when temperatures remain constant with time) heat flow was achieved at specific subzero temperatures (−2.5, −5, −10, −20, and −30°C) and λ of soilcrete was calculated based on the temperature distribution. Lab results showed that the values of λ of soilcrete ranged between 1 and 2 W/(m·°C) and generally increased as the temperature decreased after freezing. The effect of cement content on λ was minor. Furthermore, λ of soilcrete was estimated by several empirical methods for frozen soils and compared with the experimental values. It was shown that values from empirical methods overestimated the values obtained from the lab tests.