Study on the mechanism of crystallization deformation of sulfate saline soil during the unidirectional freezing process

The freezing of sulfate saline soil involves the coupling effect of heat and mass transfer and crystallization deformation. The influence of salt content and temperature on the crystallization of ice and salt was analyzed by using a one‐side freezing experiment. Based on the effect of solute and temperature on water activity, a crystallization kinetics model of ice–water phase change in saline soil was established. The application of supersaturation in the crystallization kinetics model of solution–crystal phase change is improved with the Frezchem model. The calculated results are compared with experimental data to validate the effectiveness of the proposed model. the study shows that: (a) crystallization can be well illustrated by the proposed model based on the concepts of the formation factor of ice crystals and solution supersaturation; (b) convection and diffusion are the main means of salt redistribution, which cause the accumulation of salt above the freezing front and the formation of discontinuously distributed–layered salt crystal zones; and (c) the alternate crystallization of ice and salt increases variation i solute concentration and then increases crystallization pressure, which leads to the deformation of salt expansion.