Experimental study of freeze–thaw deformation in soil modified with phase change materials

Previous studies have confirmed the potential use of phase change materials (PCMs) in reducing temperature fluctuations in soil. However, PCM’s impact on soil volumetric deformation due to freeze–thaw (F-T) cycles remains understudied. To address this gap, the thermal conductivity, Atterberg limit, permeability, and F-T deformation were investigated for the control and two PCM-modified soils. PCM-A and PCM-B were utilized in modifying the soil, which had phase change points of 10.65°C and −2.75°C, respectively. The results reveal that PCM-modified soils have less F-T deformation than the control soil, with PCM-A showing the least deformation. The increased plastic limit, decreased thermal conductivity, reduced permeability coefficient and decay of supercooling temperature reveal that the F-T deformation of PCM-modified soil diminishes with the addition of PCM. For PCM-A, a plastic limit exceeding its moisture content of 18 %, lower thermal conductivity, and an approximately equal permeability coefficient indicate the least frost heave during freezing. Based on grey incidence analysis, the phase change temperatures have a minimal impact on F-T deformation compared to other physical properties. The difference in the grey incidence between frost heave and phase change temperatures also indicates the stronger restraining effect of PCM-A on soil’s frost heave. PCM-A with an optimal content not exceeding 6 % is recommended for restricting F-T deformation.