Comparative effects of selected wastes on the indices and strength properties of laterite soil

Abstract

This study carried out comparative analyses of the potentials of induction furnace slag (IFS), rice husk ash (RHA) and saw dust Ash (SDA) on the geotechnical properties of the A-7-6 and CL classified laterite soil obtained from Imota, Lagos State. By these classifications, the laterite soil is a poor subgrade material that requires stabilization before it could be utilized for engineering applications. Moreover, IFS, RHA and SDA are agro-industrial waste materials, whose poor disposal systems pose serious concerns to the environment. As one of the sustainable ways of reusing these wastes, the laterite soil was treated with 0-10% of these wastes by mass of the soil sample. The impacts of these admixtures on the grain size distribution, specific gravity, Atterberg limits, compaction, uniaxial compressive strength (UCS) and California bearing ratio (CBR) were determined based on relevant standard procedures. The study revealed that the percentage of specimen passing 0.075 mm sieve increased with increase in admixture contents. However, the specific gravity of the soil decreased with the addition of RHA and SDA but increased significantly with IFS treatment. The plasticity index of the stabilized samples reduced with increasing IFS content, while it increased with RHA and SDA additions. UCS values increased from 108.90 kPa for the natural soil to 150.90 kPa, 146.57kPa and 121.52 kPa at 10% addition of IFS, RHA, and at 8% SDA, respectively. The CBR increased from 63.38% for the natural soil to 157.19%, 98.98% and 88.94%, and from 9.12% to 38.59%, 24.74% and 14.13%, for IFS, RHA, and SDA, respectively under unsoaked and soaked conditions, respectively at 10% stabilization. The research findings indicate that IFS have significant impacts on soil properties than RHA and SDA, and the addition of 4% IFS makes this soil a suitable material for both subgrade and sub-base road courses.