Strength enhancement in high silica wood ash stabilized lateritic soil using sodium tetraoxosulphate VI (Na2SO4) as activator

Abstract

Strength enhancement of waste wood ash (WWA) stabilized lateritic soil, classified as A-7-5(11) and ML (silt), was investigated using sodium sulphate (Na2SO4) as an activator. Basic laboratory geotechnical tests for assessing compacted soil as road construction material were carried out on the samples prepared by admixing the lateritic soil with the predetermined percentages of WWA and Na2SO4 relative to the mass of the soil. The results showed reductions in the percentage of fines as both WWA and Na2SO4 contents increased. Liquid and plastic limits of the lateritic soil increased with the increasing contents of both WWA and Na2SO4, and this led to reduction of the plasticity index and hence improved the workability of the soil. The maximum dry density (MDD) of soil increased with corresponding decrease in optimum moisture content (OMC) as the percentage of Na2SO4 increased. However, MDD increased up to 3% WWA and thereafter decreased. OMC decreased at 3% WWA and then increased with increasing content of WWA. The California bearing ratio increased with increasing contents of WWA but with pronounced increment at 4% Na2SO4. Satisfactory performance of the lateritic soil was observed with up to 9% WWA and 4% Na2SO4 activation, at which the soil could be used as road subgrade material