Study on phase transition of salt crystallization during cooling of saline soil

Along with the cooling process, the solution in the pores of saline soil will undergo phase transformation. Theoretical analysis and experimental research were conducted on the salt crystallization behavior of saline soil during the cooling process. Firstly, starting from thermodynamic theory, the theoretical expression for the initial crystallization radius of salt solutions in pores was given by considering the chemical potential equilibrium between phase transitions and the Young-Laplace equation. The relationship between the initial crystallization radius, temperature, and initial salt content was analyzed. Secondly, a theoretical model was established to predict the content of pore solution and salt crystals, and the influence of temperature and salt content on salt crystallization behavior during the cooling process was analyzed through iterative calculations. Finally, the effectiveness of the theoretical model was verified by conducting indoor cooling experiments on saline soil. The results show that saline soil is affected by both temperature and salt content during the cooling process. As the temperature decreases and the initial salt content increases, the liquid saturation of saline soil decreases and the salt crystal content increases. The initial salt content has an important impact on the salt precipitation temperature of saline soil, and the salt precipitation temperature increases with the increase of the initial salt content. The salt swelling deformation of saline soil mainly occurs in the early cooling stage, and the amount of salt swelling deformation in the early cooling stage is greater than that in the late cooling stage.