Stabilisation of Tropical Black Clay using Calcium Carbide Residue and Coconut Shell Ash

Abstract

A Tropical Black Clay (TBC), obtained by method of disturbed sampling, at a depth of between 0.5m to 1.5m, at Gwako village, Abuja, Nigeria, was treated with up to 10% each of Calcium Carbide Residue (CCR) and Coconut Shell Ash (CSA), at 2% variations. Effect of the additives was investigated with respect to compaction characteristics (Maximum Dry Density-MDD and Optimum Moisture Content-OMC) and Unconfined Compressive Strength (UCS). Results of index properties of the soil indicated that it classified under CH and A-7-5, according to Unified Soil Classification System (USCS) and American Association for Highway and Transportation Officials (AASHTO) respectively. There was a general decrease in MDD of the treated soil with increase in dosage of the additives, while the OMC increased with increase in dosage of the additives. Unconfined Compressive Strength (UCS) of the treated soil showed general increase with both increase in dosage of the additives and curing period. It was therefore, concluded that although, 1700 kN/m2 UCS was not achieved within the composition considered, CCR and CSA indicated positive potentials for treatment of tropical black clays.