Use of Sawdust Blended with Bentonite and Cement Mixtures to Retain Diesel Oil Contaminants as a Liner in a Landfill

Abstract

This paper presents the use of sawdust (SD), an industrial waste blended with bentonite and Portland cement (PC) mixtures as a liner in a landfill, to minimize the migration of leachate contaminating the subsurface environment. An experimental programme has been evaluated to study the effect of SD content on the liquid limit (LL), free swell index (FSI), compaction, hydraulic conductivity and strength characteristics of blending with bentonite and PC mixtures. The deionized water (DIW) and diesel oil contaminant (DOC) were used as permeating fluids in the study. The LL, FSI, maximum dry density and strength of the mix blends decreased; on the other hand, the optimum moisture content and hydraulic conductivity increased with increase in SD content, respectively. On permeation of DOC for all the mix blends, lower hydraulic conductivity is obtained as compared to DIW. In addition to it, the UCS tests samples were examined for quantitative energy dispersive X-ray spectrometer at 0-, 14- and 28-day curing period. It reveals the increase in Ca/Si ratio and decrease in Al/Ca ratio resulted in the strength improvement with an increase in the curing period. Powdered X-ray diffraction analysis suggested the formation of the hydrated cementitious product in the mix blends. Based on the results obtained from the study, the optimum percentage of sawdust to be effectively used as liner to prevent groundwater contamination was found to be less than or equal to 20%.