Use of Coconut Husk Ash and Calcium Carbide Residue as Laterite Soil Stabilizers

Abstract

The ability to blend naturally occurring soil with some industrial and agricultural wastes to give better engineering properties in both strength and waterproofing is very essential. Thus, this research examines the importance of coconut husk ash (CHA) and calcium carbide residue (CCR) as laterite soil (LS) stabilisation. Various tests carried out were XRay Fluorescence (XRF) spectroscope analysis and particle size distribution of the LS while the stabilised LS with varying percentages of CHA and CCR at 2, 4, 6, 8 and 10% each using consistency limits, compaction and California Bearing Ratio (CBR) were also investigated. One-way analysis of variance (ANOVA) was used to analyse the stabilisation effects. The XRF spectroscope analysis revealed that silica-sesquioxide ratio of the soil is 0.88 indicating it as laterite while CHA and CCR are classified as class N pozzolan and cementitious material (CaO of 68.5%) respectively. The additives (CHA and CCR) at 4% improved the workability and decreased the infiltration capacity of the LS as it reduced the plasticity index from 24.6% to 6.2%. Also, at 4% CHA and CCR, the maximum dry density and optimum moisture content of the LS increased from 17.7 𝑘𝑁/𝑚3 to 20.5 𝑘𝑁/𝑚3 and decreased from 11.8% to 9.1% respectively which enhanced the compactness of the LS. The blend of 10% CHA and CCR have the highest CBR value of 20.6% which significantly improves the strength of the LS. ANOVA showed that both additives had statistically significant (p < 0.05) effects on the CBR of the LS. The results indicated that the use of CHA and CCR can improve the engineering properties of laterite soil for use as subgrade pavement.