Pore ice evolution and its mechanical influence in a freezing saline sandy soil

Frozen saline sandy soils are widespread in coastal region or riverbank and river delta but rarely studied in the evolution of ice during freezing. This study uses Ottawa sand mixed with a saline solution for in-situ freezing tests and real-time imaging through X-ray CT. Results indicate that ice prefers to form in water-rich pores independent of pore size in coarse-grained soils with large pores. The Logistic model can describe the growth of pore ice, and the growth rate is fastest when the ice content reaches half its maximum. Higher salt-water mass ratio inhibits the pore ice isotropic growth and promotes the anisotropy in ice orientation. Regarding morphology, pore ice tends to evolve from an isotropic compact shape to an anisotropic elongated or bladed shape. Further analysis of sand skeleton deformation reveals that the deformation would diminish as freezing proceeds in unsaturated specimens, while saturated specimen accumulates vertical compressive deformation during freezing. These findings help to understand the evolution of pore ice and potential mechanical behaviors in the freezing of saline sandy soils.