Effects of desiccation-induced cracking and leachate infiltration on the hydraulic conductivity of natural and olivine-treated marine clay

Clayey soils rich in smectite are commonly utilized for the construction of liner materials in engineered landfills owing to their low hydraulic conductivity. However, due to the high swelling potential of such clayey soils, their hydraulic conductivities are adversely influenced by desiccation cracking. In addition to cracks, the hydraulic conductivity of the clayey soils might also be affected by the complex composition of landfill leachate. The current study aims, therefore, to assess the effects of desiccation-induced cracks and leachate infiltration on the hydraulic conductivity of natural and 30% olivine-treated marine clay specimens. Clay specimens were prepared using three compactive energies and subjected to cycles of drying–wetting and hydraulic conductivity testing using tap water and field leachate as the permeants. Test results demonstrate significant improvements in the hydraulic conductivity of the olivine-treated clay samples after cycles of drying–wetting upon permeation with water and leachate. These improvements are attributed to the formation of magnesium–aluminate–hydrate and magnesium–silicate–hydrate gels as confirmed using microstructural analyses. The gels are responsible for minimizing the adverse impact of cracks on the hydraulic conductivity of the treated clay specimens. The findings indicate that olivine can be employed as a suitable additive in decreasing the hydraulic conductivity of soils prone to cracking.