Compacted sawdust ash–lime-stabilised soil-based hydraulic barriers for waste containment

Abstract

This study examined the impact of sawdust ash–lime (SDAL) stabiliser on the geotechnical characteristics of lateritic soil as an effective hydraulic barrier system for landfill liner application. SDAL mixtures in the ratio 2:1 were added to the lateritic soil at varying percentages between 0 and 10%. The soil–SDAL mixtures were then compacted using four integrative methods: reduced Proctor, standard Proctor, West African Standard and modified Proctor. Index geotechnical tests were carried out on the lateritic soil; hydraulic conductivity and unconfined compressive strength (UCS) tests were carried out on the compacted SDAL-stabilised lateritic soil. Results show that the addition of SDAL decreased the maximum dry density and increased the optimum moisture content. Hydraulic conductivity (k) values decreased with low (i.e. 2%) addition of SDAL, while UCS increased with SDAL addition. Apart from the SDAL addition, the compacting effort and the curing periods also had an effect on the hydraulic conductivity and UCS values of the samples. Compacted SDAL-stabilised lateritic soil (with as little as 2% SDAL) can therefore be applied as a low-cost soil-based hydraulic barrier for waste containment.