Long-Term Performance of Liners Subjected to Freeze-Thaw Cycles

The technique of using clay-sand mixtures as liners has been widely used in several geotechnical projects where hydraulic barriers or waste-buffer layers are required. During weather fluctuations and below-zero temperature conditions, these layers can be subjected to successive freeze-thaw cycles. The serviceability of such liners needs to be examined during their lifetime for efficiency and function under such suspected weather conditions. The hydraulic conductivity over the long run needs to remain within the acceptable design ranges. In this study, the efficiency of two different clay-sand liners were examined under the effect of freeze-thaw cycles for extended serviceability. The hydraulic conductivity under a continuous discharge rate of these layers was measured before and after applying 15 successive freeze-thaw cycles for more than half a year. The results indicate dramatic changes in the hydraulic conductivity parameter for the specimens subjected to freeze-thaw cycles depending on their mineralogical composition and applied stress. These changes were found to be related to the sealed material composition and placement conditions. The data obtained were found of interest and can be utilized for evaluating the efficiency of the liners in areas subjected to extreme environmental exposures including freeze conditions over extended periods.