ASSESSMENT OF THE INFLUENCE OF TERMITES ON GEOTECHNICAL PROPERTIES OF SOME LATERITIC SOILS IN ADO-EKITI, SOUTHWESTERN NIGERIA

Abstract

The determination of the influence of activities of termites on the engineering properties of Termite reworked soils and non-reworked surrounding soils from Ado-Ekiti, Southwestern Nigeria: was carried out. Two termite hills from two locations were chosen. Twenty bulk representative soil samples depicting twelveTermite reworked soils and eight non-reworked surrounding lateritic soil samples were collected. Some geotechnical and geochemical parameters such as grain size distribution, consistency limits, linear shrinkage, compaction characteristics, California characteristics, compressive Bearing Ratio (CBR), triaxial compression strength from. moulded bricks, permeability characteristics, X-ray and Differential Thermal Analysis (DTA) of the soils were determined. The results of these tests showed that the specific gravity of grains and the CBR of the termite reworked soils are higher than those of the surrounding soils. However, the plasticity indices and linear shrinkage of the termite reworked soils were significantly lower than those of the surrounding soils while the triaxial test showed that the angles of internal friction and cohesion of termite reworked soils are higher than those of the surrounding soils. Also, compaction characteristics showed that there is an increase in the value of Maximum Dry Density (MDD) with a reduction in the Optimum Moisture Content (OMC) of termite reworked soils. The permeability test showed that termite reworked soils are more permeable than the surrounding soils. Also, termite reworked soils have higher strengths as revealed by compressive strength tests carried out on moulded bricks made from them than those made from non reworked soils. The chemical analysis of the soils showed that termite activities increase iron, manganese, magnesium, calcium, potassium, zinc and phosphorus levels of the soil. Aluminum was also detected only in the soil around the queen at' the termites. X-ray analysis and DTA of the soils showed that, Kaolinite, the major clay mineral, increases with the activities of termite: All the geotechnical tests carried out favoured termite reworked soils as a better engineering soil than the surrounding lateritic soils. Findings from this work indicate that reworking by termites has improved the engineering properties of the studied termite reworked soils.