GEOLOGICAL AND GEOTECHNICAL CHARACTERIZATION OF EARTH MATERIALS FOR INFRASTRUCTURAL DEVELOPMENT IN JOS-BUKURU NORTH CENTRAL NIGERIA

Abstract

The geological and geotechnical assessment of earth material plays a vital role in the construction of infrastructures. The study involves; reconnaissance survey, sample collection, and laboratory analysis. A total of twenty-four (24) disturbed and undisturbed soil samples were collected from the field by the use of digging tools and core cutter by making a boring pit at a depth of 1.5m and 0.85m wide. The results showed that the values of the Atterberg limit; liquid limit (LL), plastic limit (PL), plasticity index (PI), shrinkage limit (SL), liquidity Index (LI), consistency index (CI), and shrinkage index (SI) ranged from 33.0-52.0%, 15.0-37.0%, 7.0-29.0%, 4.0-28.0%, -2.76-0.18%, 0.34-1.83%, and 7.0-46.0% respectively. From the results of the particle size analysis, the percentage passing of gravel, sand, silt, coefficient of uniformity (Cu), and coefficient of curvature (Cc), of the soils ranged from 20.0-30.0%, 30.0-75.0%, 5.0-60.0%, 1.03-9.17 and 0.04-2.74. The average values of the Natural Moisture Content (NMC) ranged from 2.9-24.8%, Specific Gravity (SG) from 1.53-2.65, for the Compaction, the optimum moisture content (OMC) ranged from 8.1-31.0%, maximum dry density (MDD) from 1.22-1.82 g/cm3. The findings have revealed that the geology of the area is made up of four lithologic units; Laterite, Jos Biotite Granite, N’gell Biotite Granite, and Rayfield Gona Biotite Granites. The soil type is of silty-clay and clay, with medium to high degree of plasticity, dehydrated and brittle soils capable of exhibiting elastic deformation under load, poorly graded soils with mild flexibility, low compressibility and shear strength.