Experimental study on frost heave characteristics of PCM-clay under one-dimensional freeze-thaw

The clay incorporated with phase change material (PCM-clay) has the characteristics of freezing resistance and temperature control, which makes it possible to construct clay core walls, channels, embankments, roads and other scenarios with negative temperature. According to the environmental characteristics of daily cyclic freeze-thaw effects on the construction site in winter, a series of repeated one-dimensional freeze-thaw experiments under closed system, step thermoregulation and shallow freezing conditions in a closed system are simulated indoors to study the frost heave characteristics of the PCM-clay and the law and mechanism of frost heaving development under the action of freeze thaw cycles. The results show that the frost heave characteristics of the PCM-clay is improved compared with that of the clay without PCM (pure clay). After freeze-thaw cycles, the final frost heaving amount of the PCM-clay is far less than that of the pure clay under the same freeze-thaw cycles. The downward moving rate of soil freezing front and the degree of moisture migration also decrease. After several freeze-thaw cycles, the cryogenic structure of the pure soil has developed more significantly, while the PCM-clay does not exhibit obvious frost heave sensitivity, and the formation and development of cryogenic structure are very slow. The analysis shows that the low water content, large porosity, high latent heat energy storage, freezing shrinkage and hydrophobicity of the PCM are the main reasons for improving the frost heave characteristics of the PCM-clay. This study can provide a theoretical basis for the PCM-clay as a construction material for potential dam core walls, channels, embankments, and roads to provide winter construction frost protection in cold regions.