Effect on engineering properties of ground granulated blast furnace slag admixed with laterite soil, cement and bentonite mixtures as a liner in landfill

Abstract

This paper showcases the geotechnical and environmental engineering properties of ground granulated blast furnace slag (GGBS, a byproduct of iron-ore) admixed with local laterite soil (LS), bentonite (BT) and cement (CT) mixtures as landfill liner. The main aim of this study is to determine the effect of GGBS on LS (i.e. effect of binder material with filler material) and to study the effect of GGBS-LS blended with varied BT and CT mixtures (i.e. binder-filler material in partial replacements), to perpetrate as a landfill liner material. Overall, a wide range of fifteen unique mix proportions was chosen in this study and are categorized into five series. Laboratory tests such as consistency limits, free swell index (FSI), Proctor compaction, hydraulic conductivity (HC), leachate characteristics (LC) and unconfined compressive strength (UCS) with post-testing analysis were conducted to evaluate the optimum mix. From the test results, the consistency limits and FSI decreased with an increase in GGBS content for all the mixes. In compaction tests, the addition of GGBS increases the dry unit weights and reduces the water contents. The HC decreased with the addition of GGBS quantities when permeated with deionized water and diesel oil as permeant fluids. In the LC, the concentrations of heavy metals (i.e. Cr, Co, Cd, Fe and Pb) in diesel oil decreased and removal efficiencies increased for lower HC values than higher HC values. The UCS values increased with an increase in GGBS quantities and curing intervals for all the mixes. The microstructure and mineralogical analysis revealed the identification and confirmation of new cementitious products which ameliorated the UCS values. Hence, from this study, when GGBS admixed with filler and other binder material established to be an efficacious and eco-friendly solution which not only reduces the disposal problem but improves the engineering properties and prerequisite as landfill liner.