EFFECT OF HIGH LOST ON IGNITION (LOI) CONTENT CEMENT KILN DUST ON THE INDEX PROPERTIES OF BLACK COTTON SOIL

The preliminary investigation carried out on a black cotton soil shows that it falls under A-7-6 (16) using AASHTO classification and CL according to Unified Soil Classification System (USCS). The tests carried out on the cement kiln dust treated soil showed that the liquid limit of the natural soil increased from 48.2% to a peak value of 51.8% at 2% CKD treatment and thereafter decreased with higher CKD content. The plastic limit also increased from 27.2% for the natural soil to a peak value of 36.8% at 4% CKD treatment. The plasticity index value, decreases from 21.0% for the natural soil to a minimum value of 12.8% at 6% CKD content. The maximum dry density (MDD) for British Standard Light (BSL) and British Standard Heavy (BSH) compactive efforts increased to peak values of 1.66 and 1.91 Mg/m3 at 6% and 4% CKD contents respectively. The MDD for West African Standard (WAS) compactive effort increased with higher CKD content. The Optimum Moisture Content (OMC) for BSL and BSH compactive efforts increased up to 6%CKD content then decreased with higher CKD content. For the WAS compactive effort, the OMC generally decreased with higher CKD content.