Unfrozen water in freezing and thawing soils: Kinetics and correlation

The experimental data indicate that water in freezing or thawing wet soils undergoes a gradual phase change. The mathematical forms of reported correlations of the unfrozen water content of soils varies from researcher to researcher. An improved theoretical treatment of the gradual freezing/thawing process provides insight into the mechanism of the gradual phase change of water in wet soils and a proper means of correlating experimental measurements. Direct numerical solution of the resulting ordinary differential equation may provide accurate prediction of the unfrozen water content of wet soils, when accurate soil property data are available. Two approximate analytical solutions are derived using average thermal properties of the soil constituents. The simpler of these analytical solutions is applied to various data and shown to be sufficient fur all practical purposes. The analysis presented in this article demonstrates that the unfrozen water content can be adequately correlated by means of an exponential decay function shifted by the amount of the water adsorbed over the soil grains, which cannot freeze.