This study investigates the effects of different compactive efforts on the strength of laterites stabilized with sawdust ash (SDA). Laterites in the categories of A-7-5 and A-7-6 were considered because they are not suitable in the natural states as subgrade materials. The geotechnical properties of the laterites in their natural states were determined. The sawdust was burnt and sieved through 600micron. The sawdust ash (at 2%, 4%, 6%, 8% and 10%) was added to the laterites and the atterberg limits were determined, while the California bearing ratio and Unconfined compression test were determined using three compactive efforts (596, 1192 and 2682KN-m/m3).It was generally observed that the maximum dry densities of the natural and stabilised laterites increase with increase in the compactive efforts, while the optimum moisture contents reduce. The plasticity indices of the laterites increased with the addition of SDA. The optimum values of the MDDs (2006 and 1878 kg/m3) were observed at 4% and 6% SDA of 2682 kN-m/m3 compactive effort for samples A and B, respectively. The soaked and unsoaked CBR values of the soils at natural state are 4.89 and 16.33%, and 3.4 and 5.62% for samples A and B, respectively. The results indicate that the higher the compactive efforts, the higher the CBR values of the two samples. Increase in SDA contents of soil samples A and B showed a non-predictable trend on their CBR values. The Unconfined Compressive Strength values at natural and treated states fell below the requirements. Generally, it was found that the use of sawdust ash alone as stabilizer was not effective. Therefore, it was concluded that future studies should consider the use of the sawdust ash in combination with cement or lime.

Two different samples of soil tested as A-7-5 and A-7-6 were stabilized respectively with lime and cement. The samples were stabilized with the additives in steps of 2% and subjected to laboratory tests such as consistency limits, compaction, California bearing ratio (CBR) and unconfined compressive strength (UCS) until it reached 10% additives by weight of dry soil sample. The Proctor energy type of compaction and soaked method of CBR was adopted for the research while the compressive strength of the soils were measured in an unconfined state at days 1, 7 and 14 respectively. The plasticity index (PI) of the soil samples increase at 2% additives which later reduces with further increase as the additives contents. The soil samples attained their maximum dry densities at 6% cement and lime respectively, with cement being more effective compared to lime and the water content needed to achieve maximum dry density of the soil were higher in cement than in lime. The CBR values of the soil appreciate with increase in the additives content as indicated in the rise from 1.12% at natural to 7.26% at 6% cement content. The UCS of the lime stabilized soil improved better than that of cement stabilized soil with respect to the age of curing.  Keywords- Stabilization, Lime, Cement, Soil, Laterite.

Spatial assessment of groundwater degradation has been carried out in Ado-Ekiti using physicochemical analysis and Geographical Information System (GIS). Groundwater samples from 108 wells were analyzed on a regional basis. Application of GIS enabled the preparation of various thematic maps which were analysed in terms of groundwater quality standards for drinking and domestic utility. The thematic maps of pH, Total Hardness, Total Dissolved Solids (TDS), Chloride, Calcium and Nitrate concentrations produced were reclassified for integration in a GIS environment to produce the groundwater quality map. Anthropogenic influences were observed on the groundwater quality status of the study area as non-potable groundwater was delineated at the built-up areas and regions adjacent to streams and rivers. The integration of the thematic maps proved useful for the delineation of zones of groundwater quality suitable for human consumption and domestic purposes. Spatial analysis of the groundwater quality is essential for a proper understanding of the present environmental challenges and a projection into the future. This will facilitate quick decision-making for holistic groundwater development and management.