Application of mango leaf waste ash in the compacted lateritic soil pavement construction

Abstract

Road pavement requires a standard level of strength before it can be safely used to accommodate wheel loads. This strength can be achieved by compacting and stabilizing the soil with Portland cement. However, the environmental problem associated with its production has made researchers delve into substitute material. An investigation was conducted on the effectiveness of mango leaf waste ash (MLWA) in stabilizing compacted lateritic soil (CLS) for road pavement (RP). The various tests conducted on the LS and LS- MLWA in the laboratory include index properties, Atterberg limit, compaction characteristics (using British standard light energy), California bearing ratio (CBR), and unconfined compressive strength (UCS). The results were analysed using analysis of variance (ANOVA). The LS was treated with varying concentrations of MLWA up to 10% by soil dry weight. The compacted natural lateritic soils (LS) used in the study were categorized as A-7-6 (5) and CL under the America Association of State Highway Officer (AASHTO) and Unified Soil Classification System (USCS) classifications, respectively. The result of the atterberg limit indicated an improvement in the plasticity of the treated soil. The maximum dry density (MDD) value of the treated soil lessened with an increase in optimum moisture content (OMC). MLWA content of up to 6% resulted in an improvement in both the CBR and UCS values. However, UCS values of the cured for 7, 14 and 28 days fell short the TRRL road Note: 31 recommendation and Nigerian General Specification for Road and Bridges, which is 1710 kN/m2. Analysis of variance (ANOVA) test results displayed that the Atterberg limits, compaction parameters, CBR, and UCS were statistically significant for the MLWA-LS mixture. The combination of LS and 6% MLWA produced an optimal mixture that significantly improved the soil's strength, making it suitable for use as sub-base material in roads with low to moderate traffic.