Abstract:
The assessment of the properties of lateritic soil stabilized with ashes from cocoa
pods and palm kernel shells as partial replacement of cement was carried out.
Samples of lateritic soil were collected at varying depths from 0.5m and 1.5m at a
borrow pit after the top soil had been removed. The samples were air-dried and
thoroughly mixed to ensure a homogenous sample. Each of the cocoa pods and palm
kernel shells collected dried with respective inherent moisture content of 0.5% and
0.1% and was oven dried to 0% moisture content at a temperature of 110°C and
further heated in an open top kiln to a temperature of 800°C for cocoa pods and
10000C for palm kernel shells when appreciable ashes began to appear in the
furnace. Varying proportions of cement and ashes from cocoa pods and palm kernel
shells used were expressed as percentage of the dry weight of the soil samples. The
total additive contents used were 2%, 4%, 6% and 8% for each test carried out on the
samples. Some geotechnical parameters such as: classification (specific gravity,
moisture content, grain size distribution and consistency limit); Compaction;
California Bearing Ratio; Chemical compositions of the additives were determined.
The cost analyses of the additives were also conducted. The result of the consistency
limit of the natural soil gave liquid limit of 34.0% and plasticity index of 16.2%, the
soil thus classified in group A-2-6(0) and generally the results of the treated samples
showed significant decrease in the plasticity index when compared with the natural
soil samples and most significant in C. The maximum dry density and the C.B.R. of
the treated samples increased above the natural soil in all cases, exceeding 2000kglm3 and 80% respectively at 6% which are the minimum permisable forunsoaked C.B.R values for base course. The results of the chemical analysis of the additives used also showed that the ashes have Fe, Mg, Na and K which compared favourably with cement but palm kernel shell ash was deficient in calcium (Ca) which is the major constituent of cement. Cocoa pods and palm kernel shells were treated as wastes, their use for this purpose will be of economic benefit since they served as suitable partial replacement when stabilizing with cement, usually an expensive commodity.
