Sawdust Stabilization of Lateritic Clay as a Landfill Liner to Retain Heavy Metals

Compacted clay soils are commonly used as landfill liners. This research work was aimed at investigating the suitability of sawdust amended lateritic clay as a landfill liner to adsorb Pb and Cd, thereby protecting underground water. Index properties, compaction, strength and permeability tests were conducted on the unstabilized and stabilized clay in order to determine the effects of the sawdust on the geotechnical properties of the lateritic clay. Batch kinetics tests were utilized to determine the capacity of the clay and sawdust-amended clay to adsorb Pb and Cd. The soil, classified as A-7-6 and CH by AASHTO and unified soil classification systems, respectively, was admixed with 0%, 5%, 10%, 20%, and 30% sawdust by dry weight of the soil. Test results show that the specific gravity, plasticity index, maximum dry unit weight and unconfined compressive strength of the soil decreased with increasing sawdust content while the optimum moisture content and hydraulic conductivity increased with increasing sawdust content. The stabilization of the lateritic clay with ≤10% sawdust content was recommended for use as landfill liners, as they meet the standard hydraulic conductivity requirement and present a good adsorption of Pb and Cd