Effects of wetting-drying cycles on the air permeability of compacted Téguline clay

• Published in: Engineering geology Vol. 228; pp. 173 - 179
• Main Authors: He, Yong, Cui, Yu-Jun, Ye, Wei-Min, Conil, Nathalie
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 13.10.2017
• Subjects: Air permeability; Micro-cracks; Téguline clay; Wetting-drying cycles; Micro-cracks; Air permeability; Téguline clay; Wetting-drying cycles
• ISSN: 0013-7952; 1872-6917
• DOI: 10.1016/j.enggeo.2017.08.015

Due to their low permeability and self-sealing ability, compacted clays are often considered as barrier materials in waste disposal. In most disposal cases these materials are exposed to atmosphere and thus subjected to wetting-drying cycles. As a result, their microstructures might significantly change and sometimes cracks can occur, giving rise to changes in hydro-mechanical properties. It is expected that this microstructure change can be evidenced through changes in air permeability since any growth of micro-cracks can greatly affect the air permeability. In this study, the air permeability evolution of Téguline clay compacted at 12.7% and 16.0% water content during wetting-drying was investigated. The results show that the final water content, void ratio and degree of saturation decreased with the increase of wetting-drying cycles. Cracks occurred in the radial direction on the sample surface rather than in the axial direction after 4–5 wetting-drying cycles. The coefficient of air permeability of the compacted samples is larger than those of the samples subjected to wetting-drying cycles. It also appears that the coefficient of air permeability increases with wetting-drying cycles and the initial water content has insignificant effects on the wetting-drying behaviour and air permeability characteristics. Furthermore, the coefficient of air permeability in the axial direction is larger than the one in the radial direction after the initial 2 wetting-drying cycles, suggesting an anisotropic behaviour with larger shrinkage in the axial direction. These findings show clearly that the effects of wetting-drying cycles on soil microstructure can be effectively investigated through air permeability measurements. •Shrinkage mainly occurred in the first wetting-drying cycle.•Larger air permeability at larger air-filled porosity•Development of micro-cracks with the wetting-drying cycles•Anisotropy of air permeability