Suitability of Lateritic Soil in Oluku Community, South-South, Nigeria As a Borrowed Pit Material For Construction Purposes

Laterite is a highly weathered material rich in secondary iron and aluminium oxides, which is of great use in road and building construction. This material is found in a larger quantity in the Oluku community; however, there is no prior knowledge of the geotechnical properties and suitability of the lateritic soils for construction purposes. This study investigates the suitability of the lateritic soil from the Oluku community as a borrow pit material for construction purposes. Soil samples were collected from 5 different pits within the study area and at different depths of 1.3, 1.4, 1.2, 1.3 and 1.5 m, respectively, by hand auger. Laboratory tests such as particle size distribution analysis, specific gravity, Atterberg limits, compaction test and California Bearing Ratio (CBR) test were conducted on the soil samples by BS 1377. The particle size distribution test results revealed that the percentage passing of the soil samples ranged from 31.62 to 67.60%, indicating poor materials. The specific gravity results ranged from 2.3-2.8, while the compaction test results revealed that the optimum moisture content (OMC) and maximum dry density (MDD) ranged from 8.10-15.70% and 0.70 Mg/m³-2.04 Mg/m³ respectively. The consistency limits results show that liquid Limit, Plastic Limit and plastic index ranged from 19.73 to 28.52%, 11.89 to 19.03% and 6.70 to 9.82%, respectively. The soaked and un-soaked CBR values ranged from 2.24-4.37 % and 10.35% to 22.65% respectively. These results were compared to the specifications established by the Federal Government of Nigeria for roads and bridges (1997) and British Standards Methods of Test for Soil for Civil Engineering Purposes (BS 1377: 1990). Overall, the result revealed noticeable deviations from standards due to the presence of a high content of silty clay. This implies that the soil samples present at the Oluku community are not unsuitable as borrow pit material and, therefore, cannot be used for construction.