Investigations into the self-healing of desiccation cracks in compacted clays

Abstract

Clay materials used for the construction of landfill liners and capping layers need to possess sufficiently low permeability, but although high plasticity clays are particularly suitable for the purpose, cracking caused by desiccation during construction or heat generated by waste degradation, may seriously damage serviceability and threaten the well-being of the environment. The research centres on the investigation of the formation and self-healing of desiccation cracks in clays of different plasticities with tests performed in a modified Rowe cell that incorporated a heating element in the base. Hydraulic conductivity measurements were made on samples that were subjected to several cycles of desiccation and re-saturation under different confining pressure conditions. The results show that following re-saturation desiccation cracking increased the hydraulic conductivity of high- and low- plasticity clays, by approximately half an order of magnitude. Although more cracks formed in high- plasticity clays, self-healing when the clay was re-wetted was greater than in lower-plasticity clay.