Stabilization of Lateritic Soil with Mahogany (Hardwood) Sawdust Ash

Abstract

Most naturally occurring laterites possess poor engineering properties despite their extensive uses for filling and subgrade materials. Few works have been reported on the use of mahogany sawdust ash (MSA) for the stabilization of lateritic soils. This investigation explores the effect of Hardwood Sawdust on the performance of lateritic soils as an engineering material. Particle size distribution, natural moisture content, specific gravity and consistency limits tests were conducted on soil samples obtained from burrow pits at Oke-Baale roundabout of Osogbo West-Bye pass road under construction for classification purpose. Engineering behaviour was also investigated through compaction and unsoaked California Bearing Ratio (CBR) performed on natural and admixed specimens, with the inclusion of 2, 4 and 6% MSA by weight of soil. Preliminary tests indicate that the natural samples were well-graded and rated medium as subgrade material in road construction. Reduction in the plasticity index (PI) of samples from 17 to 14% at 4% MSA were observed. MDD decreased to 1.54, 1.38 and 1.45 Mg/m3 at 2, 4 and 6% MSA respectively. The CBR increased to 18.8, 20.2 and 20.4% at 2, 4 and 6% MSA respectively. The research demonstrated that there is an impressive potential for MSA to enhance the mechanical properties of lateritic soils.