Determination Of Engineering Index Properties Of Soil For Suitable Foundation Design In Ajah, Southwestern Nigeria

This research is to determine the engineering index properties of soil for suitable foundation design in Ajah, Southwestern Nigeria. Three samples were acquired from a well bore in the area at depth of 1m, 3m and 5m. The following laboratory tests were carried out on the soil samples collected from the study area (Particle size analysis, Specific gravity, Atterberg limit, Triaxial test, and Compaction). The particle size analysis test revealed the predominance of granular materials ranging from fine to coarse sands in the sample. The specific gravity of the soil shows a gradual increase with depth, from 2.41 (at 1m), 2.50(at 3m) and 2.57(at 5m). The results from the Atterberg limit test showed that the three samples have liquid limit of 20.44%, 23.27%, and 25.61% respectively. The samples are also non plastic in nature, having neither plastic limit nor plastic index. The samples are almost cohesionless, having cohesion of 0.17, 0.95 and 0.76; and having angle of internal friction of about 13.73º, 11.62º, and 11.36º. Further analysis of the soil samples revealed that the optimum moisture content for the samples are 12.4%, 14.2% and 13.2% respectively, from top to bottom, while the maximum dry density for the samples are 1.75g/cm3, 1.68g/cm3 and 1.76g/cm3. The aforementioned properties of the soil proves that the soil is suitable for foundation, having low retention water capacity and relatively high specific gravity and permeability; high percentage of coarser grained fraction and very low percentage of clay minerals.