ASSESSMENT OF SUBGRADE SOIL STABILIZED WITH CALCIUM CARBIDE WASTE, CEMENT KILN DUST AND STEEL SLAG
Abstract
Poor subgrade soil conditions can result to inadequate pavement support and reduce pavement life and such soil may be improved through the addition of chemical or cementation additives. This paper present assessment of weak subgrade stabilized with Calcium carbide waste (CCW), Steel slag (SS) and Cement kiln dust (CKD) in terms of Plasticity Index (PI), Maximum dry density (MDD), California bearing ratio (CBR) and Unconfined Compressive Strength (UCS). Curing was done in accordance with relevant specification for stabilized soils at 0, 7, 28, and 90 days. The result indicate that beyond 6% CCW shows no change in PI, thus 6% CCW can be designated as fixation point which was used to activate the pozzolanic effect of SS while the optimum value for CKD was at 15%. MDD decreases with increase in percentages of 0 – 20% CKD from 1.88g/cm3 to 1.74g/cm3 while it increases with increase in SS. Maximum CBR was achieved at 8% CCW corresponding to 111,119, 167 and 235% and CKD (15%) are 86, 96, 133 and 176% for 0, 7, 28, and 90 days respectively. UCS for SS and CKD at their optimum value for 7, 28 and 90 days were 1296.38, 1654.28, 2198.95 kN/m2 and 1148.04, 1364.38, 1800.99 kN/m2 accordingly. The CBR and UCS results showed that the stabilized soil at 7 days curing can be used as a sub-base material for pavement construction.
