Experiment on the freezing temperature of silty clay modified by fly ash and crumb rubber

Silty clay modified by fly ash and crumb rubber has been proven to have potential as a subgrade filling in frozen areas due to its steady strength after freeze–thaw cycles and outstanding thermal insulation. To understand the freezing characteristics of this novel modified soil, its freezing temperature was measured as an evaluation index. An improved method using a Beckman thermometer was adopted to obtain the freezing temperatures from freezing curves. The freezing curves of silty clay, fly ash soil (silty clay modified by fly ash) and the modified soil (silty clay modified by fly ash and crumb rubber) with different water contents were determined. The influence of fly ash and crumb rubber on the freezing temperature of silty clay was investigated. The results indicated that the characteristics of the freezing curves of the test soils differed slightly, particularly in terms of the freezing temperatures and freezing rates. Fly ash can be applied to decrease the freezing temperature of silty clay, whereas crumb rubber increases the freezing temperature slightly. Three empirical equations without considering the effect of fly ash and crumb rubber were developed to calculate the freezing temperatures of the test soils.