Effect of Desiccation on Compacted Natural Clays

Specimens prepared from eight natural clayey soils used for clay liners and covers were subjected to cycles of wetting and drying. Volumetric shrinkage strains were recorded during drying. Specimens in which cracks formed during drying were subjected to hydraulic conductivity testing. Results of the study indicate that volumetric shrinkage strains are influenced by soil properties and compaction conditions. Volumetric shrinkage strain increased with increasing plasticity index and clay content, and as the compaction water content increased or decreased relative to optimum water content. Volumetric shrinkage strain decreased with increasing compactive effort. Specimens with the largest volumetric shrinkage strains typically contained the largest number of cracks. Hydraulic conductivity testing indicated that cracking of the specimens resulted in an increase in hydraulic conductivity, sometimes as large as three orders of magnitude.