Comparative evaluation of geotechnical properties of red tropical soils and anthills from parts of Edo State for road construction
Geotechnical tests were carried out on a total of six samples of red tropical soils developed over sedimentary and Basement terrains, made up of three soils and three termite hills samples. The soil samples were subjected to geotechnical analyses which included the Particle size analysis, Specific Gravity, Atterberg Limits and Compaction Test to evaluate their suitability for road construction. The results from the analyses showed that soils were well graded(GW) with percentage fines ranging from 28.06 to 57.8%, Specific Gravity ranged from 2.40-2.60, Liquid Limit from 36-48.5% , Plastic Limit ranged from 19-30% , Plasticity Index 15-19% and California Bearing Ratio(unsoaked) from 11-24%. For the termite soils Liquid Limit varies from 26.5-33%, Plastic Limit 19-23%, Plasticity Index 10-12% and California Bearing Ratio 24-40%. The Compaction Test results showed that the Maximum Dry Density (MDD) ranged from 1.44 to 1.65%, 1.6-1.8% and Optimum Moisture Content from 16.3 to 23.8% and 12.5 to 17.8% for soils and termite hill respectively. From the results of the analyses and in accordance with the Federal Ministry of Works and Housing, recommendations for road base, subbase and subgrade, both soils can be used for road construction as subgrade but the termite hill of Igarra indicate a better material because of its higher strength with higher MDD to low moisture content.
Keywords: Red tropical soils, Geotechnical, termite hills, subgrade, suitability, construction