An appraisal of lateritic soil modified with lime and bamboo leaf ash as hydraulic barrier

Abstract

The production of ashes from plant residue requires less energy and their application in construction industry would serve as a measure to reduce the over-reliance on the use of conventional stabilizing materials, which their means of production has negative influence on the environment, and also provides eco-friendly means of disposing such residue. This study investigates the influence of combined use of lime and bamboo leaf ash for the modification of lateritic soil as a construction material for hydraulic barrier in waste containment facilities. Natural soil was modified by adding BLA at percentage of 0%, 2%, 4%, 6%, 8% and lime at 1% 2% and 3% by weight of soil sample. Classification, compaction, volumetric shrinkage, unconfined compressive strength (UCS), hydraulic conductivity tests and microstructural analyses were carried out on both natural and stabilized soil. Results indicated that the natural soil was an A-7 and MH (sandy elastic silt) soil based on AASHTO and USCS classification respectively. The maximum dry density of natural soil increase from 1421 kg/m3 at natural state to the maximum of 1866 kg/m3, while the optimum moisture content decreased from 19% at natural to the minimum of 11.12% at 3% lime and 4% BLA addition. The volumetric shrinkage reduced from 7% at natural state to 3.58% at 3% lime-6% BLA addition and hydraulic conductivity also reduced from 5.36 × 10−5cm/s at natural state to 1.01 × 10−8cm/s at 3% lime-6% BLA. The UCS values increased from 390 kN/m2 at natural state to a maximum value of 754 kN/m2 at 3% lime 4% BLA mix, but later declined with further addition of BLA. The microstructural analyses showed that modified soil exhibited some densely packed particles than the natural soil. Based on the findings in the course of this study, addition of lime-BLA to the soil exhibited adequate strength and enhanced the soil and has a promising prospect for stabilization of lateritic soil as a construction material for hydraulic barrier in waste containment facilities.