Effect of Temperature on Hysteretic Behavior of Water Retention Capacity for Clay–Sand Liners

Abstract

The effect of temperature on the hysteretic behavior of water retention is of significant importance for unsaturated clays used as barriers for high-level radioactive waste disposal or as cover layers in waste management facilities. This study aims at investigating the effect of ambient temperature on the hysteretic behavior of water retention curves of sand-expansive clay mixtures that can be used as barriers. Two specimens consisting of mixtures of sand and expansive clay with clay contents of 15% and 30% and a specimen of pure expansive clay are considered in the study. To identify the possible thermal effects, drying–wetting soil–water retention curves for these soils are determined at selected ambient temperatures of 7, 24, and 47 °C. The vapor equilibrium technique is used to cover a wide range of suction. Different saturated salt solutions and concentrations are prepared and calibrated under nominated temperatures. The area of the hysteresis enclosed between the drying and wetting curves is calculated and used as a measure of the degree of hysteresis induced under different temperatures. The study indicates that ambient temperature has a significant impact on the hysteretic behavior of soil–water retention curves. The degree of hysteresis between drying and wetting curves tends to decrease linearly with an increase in the temperature for the investigated range of 7–47 °C.