SAWDUST ASH STABILIZATION OF WEAK LATERITIC SOIL

Abstract

This research work investigated the improvement of the properties of weak lateritic soil using sawdust ash (SDA) as the stabilizing agent. Preliminary tests such as specific gravity, moisture content, Atterberg limits, particle size distribution, Geotechnical strength tests (compaction and unconfined compressive strength (UCS) tests) were first carried out to determine the initial properties of the weak lateritic soil without the stabilizer. Based on the results of these tests, the soil was classified according to AASHTO soil classification system as A-7-5 soil which is a poor soil. The soil was then stabilized, consistency tests and strength tests such as, compaction tests and unconfined compressive strength (UCS) were performed on the soil by the addition of 2%, 4%, 6%, 8% and 10% sawdust ash to 98%, 96%, 94%, 92% and 90% by weight of the lateritic soil respectively. The results showed that sawdust ash improved the geotechnical properties of the weak lateritic soil. The optimum improvement in the properties of weak lateritic soil by stabilization using SDA is at 4% replacement. At this percentage of stabilization, the soil was classified as an A-5 soil (fair silty soil), the liquid limit decreased by 4.96%, the plastic limit decreased by 1.50%, the plastic index decreased by 15.74%, the maximum Dry Density is seen to decrease by 3.7%, the Optimum Moisture content (OMC), increased by 11.11% and the Unconfined Compression Strength increased by 26.9%. Sawdust ash is therefore found to be an effective stabilizer for lateritic soils.