Effect of lime and palm kernel shell ash on the stabilization of black cotton soil

The need to stabilize expansive soils such as black cotton soil in order to mitigate the inherent deleterious property of swelling and shrinking cannot be fully overemphasized. For the soil to be effectively utilized as subgrade it has to be stabilized and more importantly at a relatively cheap cost. So to attempt stabilizing the black cotton soil, this research uses palm kernel shell ash and lime to study the potential of stabilizing with the locally available material. For this investigation, 0, 4, 12, 16 and 20% of palm kernel shell ash was added by weight of the black cotton soil while keeping the lime percentage at 4% for all mix ratios. Experimental tests conducted in this research includes: Atterberg’s limits, specific gravity, differential free swell, compaction and California bearing ratio (CBR). The result obtained after the experiment showed that there was a marginal improvement in the value obtained for the CBR value while there was a significant dropped in the maximum dry density obtained from the result of the compaction test carried out.