Geometric models for lateritic soil stabilized with cement and bagasse ash

Agricultural and environmental demands for natural aggregates coupled with frequent increases in the price of cement and other binders have consequently escalated the cost of construction, rehabilitation and maintenance of road works. Soil stabilization emerges as an attractive option for providing low-cost roads. Bagasse-ash is an agricultural material obtained after squeezing out the sweet juice in sugarcane and incinerating the fibrous residue to ash. This residue that would have constituted an environmental problem during disposal and handling could be used as a supplement or partial replacement for cement in the cement-bound soil when converted to ash. Thus this study attempted to investigate into the effects of bagasse ash on compaction and strength characteristics of cement-stabilized lateritic soil and also to develop geometric models. The compaction, California bearing ratio, unconfined compressive strength and durability tests were carried out on the cement-stabilized soil. Constant cement contents of 2%, 4%, 6% and 8% with variations of bagasse ash from 0% to 20% at 2% intervals and all percentages used were by the weight of dry soil. The multiple regression and the least square approach was used to develop geometric equations which was made less rigorous with Minitab statistical software. The three geometric equations developed covered the relationships of cost of bagasse ash content, optimum moisture content, cement content, California bearing ratio and unconfined compressive strength at 7 days. It was observed that optimum moisture content increased progressively while maximum dry density reduced with increase in bagasse ash content. Also the increase in cement content increased both the optimum moisture content and maximum dry density. In addition, all the strength properties were increased with increase in bagasse ash content and chemistry responsible was also presented. Thus bagasse ash was confirmed to be a good admixture in soil stabilization for road-work. The models were calibrated and verified; and were found to be dependable. http://dx.doi.org/10.4314/njt.v35i4.1