Residual soils are heterogeneous due to variable weathering of the jointed rock mass. The heterogeneity of residual soils is due to the influence of relict joints, presence of boulders, and variability of the soil matrix. The repercussion of the heterogeneity is that properties of small samples of residual soil are unrepresentative of the mass. Most of Unyeghe areas are covered with granitic residual soil. Its deployment as flexible pavement material on Enwang-Unyeghe-Stubb Creek Access Road was a failure technically and economically because the predominant aluminiumsesquioxide and iron compound montmorillonite [which has the tendency to swell when their moisture content is allowed to increase] could not be curtailed by conventional plain compaction. The structural behaviour of Unyeghe residual soil from locations 1, 2, 3 and 4 when stabilized with cement-sand composite was adequate for both sub-base and base course applications. Results from composite stabilization of Unyeghe residual soil revealed soaked CBR values ranging from 91% - 168% with cement - sand content between 2% -8% and 10% - 50% respectively. The MDD of cement-sand stabilization increased from 2040kg/m3– 2140kg/m3 with similar increase in cement-sand composite. Conversely the OMC decreased from 14.2% - 8.6% average with increase in cement-sand content. Results from UCS presents a linear relationship and the values ranged from 80% - 152% and 321% - 418% on 7/28 days curing durations. Finally multple nonlinear regressed models were developed for the purpose of prediction and optimization of CBR and UCS parameters.

Full text: IJEIR_1271_Final.pdf