Abstract: During the core-wall clay construction of an earth-rock dam in cold regions, the freeze-thaw impact on core-wall clay is a major challenge. Conventional anti-freezing measures slow down normal construction process because of their serious interference with core-wall clay compaction. The core-wall clay incorporated with phase change material (PCM-clay) is able to ensure its surface temperature above the freezing point, consequently extending the winter construction time of earth-rock dams in cold regions and avoiding construction interference. This paper investigates the thermal properties of PCM-clay, based on the feasibility of using it as core-wall clay (i.e., permeability and mechanical strength). We analyze the impact mechanism of PCM content on these thermal parameters, and develop homogenized models to estimate the thermal parameters of PCM-clay (i.e., latent heat, thermal conductivity and specific heat). Numerical analysis based on these models is used to verify the effectiveness of PCM-clay in temperature control for winter construction of earth-rock dams in cold regions. Results indicate that the latent heat of phase change clay is dominated by the PCM content and its crystallinity, and the thermal conductivity and specific heat are both negatively correlated with the PCM content. Numerical models based on the phase change heat transfer theory can provide reliable simulation of temperature history, which is useful in further research of temperature control with PCM-clay.

Key words: earth-rock dam construction, core-wall clay, phase change material, anti-freezing application, thermal property