Compaction parameters of kaolin clay modified with palm oil fuel ash as landfill liner

Abstract

Soil compaction consists of closely packing of soil particles together by mechanical means, to reduce void ratio and achieve desired densification. This study examines the compaction parameters of kaolin clay pre-admixed with palm oil fuel ash (POFA), a biomass residue, for the purpose of using the composite mixture as earthen sanitary landfill liner. Standard Proctor compaction tests were conducted on four samples of kaolin clay modified with ground POFA at a step dosage of 0, 10, 20 and 30% dry mass of the clay. For ease in identification, each sample was designated as KP00, KP10, KP20 and KP30 respectively; with respect to increase in % POFA dose. In addition to compaction tests, physico-chemical properties of the samples were analyzed. Property analysis include X-Ray Diffraction (XRD), X-Ray Florescence (XRF), Scanning Electron Microscope (SEM), Specific Surface Area (SSA), the use of Particle Size Analyzer (PSA) for fine particle analysis, mass loss on ignition (LOI), and particle density test. Also, hydrogen ion concentrations in soilsolutions were estimated through direct reading of pH values. Chemical analysis show that SiO2 and CaO in each liner sample increases with increase in %POFA dose. In the presence of moisture during mellowing, prior to densification, CaO detected in the POFA may have released Ca2+ for cation exchange reaction at diffused double layers of clay particles; also, crowdingout effect of excess Ca2+ may have occured, and initiation of pozzolanic reaction. In short run reaction, these processes result in particle flocculation and agglomeration; hence, formation of friable particle aggregation. Both phenomena demand more water ingress in soil cavities. Against this background, increase in POFA dosage from 0 to 30% resulted to a corresponding increase in optimum moisture content, estimated at 12.18%. On the same note, 1.80% reduction in maximum dry density was experienced.