Effects of Expansive Clay Content on the Hydromechanical Behavior of Liners Under Freeze-Thaw Conditions
2025
Ahmed M. Al-Mahbashi | Muawia Dafalla
In several geotechnical and geoenvironmental projects, fines containing expandable clay minerals such as expansive clay (EC) were added to sand as sealing materials to form liners or hydraulic barriers. Liner layers are generally exposed to different climatic conditions such as freeze-thaw (FT) during their service lifetime. The hydromechanical behavior of these layers under such circumstances is of great significance. In this study, the impact of fine contents of expansive soil on swelling, consolidation characteristics, and hydraulic conductivity under FT conditions is examined. Different clay liners with 20%, 30%, and 60% of EC content were designed. The specimens were initially subjected to successive FT cycles up to 15 in close system criteria. The results revealed that volumetric strains attained during successive FT cycles are proportional to the content and nature of expanding minerals (i.e., montmorillonite) and reached a 4.5% magnitude value for the liner with 60% clay. Vertical strains during wetting conditions have been reduced by about 90% after the first FT cycles, which implies significant destruction in the soil structure. The yield stress indicated a 60% change, along with increasing FT cycles. The hydraulic conductivity during an extended period of 100 days shows significant changes and deterioration due to FT actions. The outcome of this study will help to predict the lifetime behavior and performance of the liner, taking into account the stability under frost conditions.
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