Assessment of engineering properties on GGBS mixtures as a bottom liner in landfills

This work examines the study of engineering properties and leachate characteristics of ground granulated blast furnace slag (GGBS) blended with laterite soil-bentonite mixtures as a bottom landfill liner. In this study, laterite soil is referred to as non-expansive and non-plastic clay; on the contrary bentonite is highly expansive and high plastic clay. Laboratory experiments were performed to quantify the effect of GGBS-laterite soil-bentonite mixtures on the liquid limit (LL), free swell index (FSI), compaction characteristics, unconfined compressive strength (UCS), hydraulic conductivity (k), and leachate tests. As GGBS percentage in the mix blend increases, the LL, FSI, optimum moisture content, k determined with deionized water/diesel oil contaminants and leachate concentration decreases, whereas maximum dry densities and UCS value increases. Furthermore, X-ray diffraction analysis and energy dispersive X-ray spectrometer was performed on UCS samples to determine the evidence of hydration reaction in mix blends at 0, 14, and 28 days curing period. The test results revealed that an increase in Ca: Si ratio and a decrease in Al: Ca ratios, augmented the UCS enhancement during the curing period. Consequently, 20% GGBS combined with laterite soil-bentonite mixes proves to be the ideal material for landfill bottom liners in waste containment systems.