Experimental Study on the Freezing Temperatures of Saline Silty Soils

The freezing temperature of soil is an important index to judge whether it is in a frozen state or not, and plays a key role in distinguishing salt expansion from frost heave. Freezing experiments on sulfate saline soil and its ion solution indicate that the initial freezing temperature of the soil is mainly determined by the properties of the ion solution. The effects of saline soil types and saline solution concentrations on the freezing temperature are also investigated. An equation to calculate the freezing temperature of the sulfate salt solution is deduced from the Pitzer ion model and its validity is verified by the experimental results. Under the assumption that the soil freezing temperature is determined by the freezing temperature of the corresponding ion solution and the energy of the ice-liquid interface, a precise relation between the soil freezing temperature and the radius of the ice-liquid interface is obtained and a general equation to determine the freezing temperature of the silty clay of the Qinghai-Tibet Plateau is proposed. Copyright (c) 2015 John Wiley & Sons, Ltd.