Stabilization of Lateritic Soil with Rubber Wood Ash and Lime for Road Construction

Abstract

This study involved the investigation of the stabilizing lateritic soil with rubber wood ash (RWA) and lime for road construction. The index and engineering properties of the soil were carried out. Stabilization of the soil was carried out by mixing the soil by weight with 0%, 2%, 4% and 6% RWA mixed with 0.5%, 1%, 1.5% and 2% lime. The soil was classified as A-6 soil group according to AASHTO soil classification system possessing the following characteristics in its natural state; average moisture content of 18.7%, average specific gravity of 2.83 average liquid limit of 34.72%, average plastic limit of 22.02%, average plasticity index of 12.70% and average California Bearing Ratio of 2.47%. Data obtained revealed that the optimum mix ratio for economic and effectiveness was 4% RWA mixed with 1.5% lime which gave a result of 11.34% for soaked sample and 14.30% for the unsoaked sample respectively. Test results also showed that increase in RWA content increased the optimum moisture content but decreased the maximum dry density. The addition of 2% constant RWA with varying lime from 0.5%-2% lime shows that the MDD decreases consistently from 1.89g/cm³ to 1.63g/cm³ with an increase in OMC from 14.00% to 21.50%. The addition of 4% constant RWA with varying lime from 0.5%-1.5% lime reduce the MDD from the initial value of 1.63g/cm³ at 2% RWA to a constant value of 1.62g/cm³ and then increases to 1.68g/cm³ at 2% lime variation when the additives became too much and vice versa for the OMC. The CBR value of the natural soil is 2.47% which shows that the sample is very poor as subgrade material. The addition of RWA only shows a little improvement but the addition of RWA and lime gave a better result.