Geotechnical Properties of Lateritic Soil from Laderin Borrow Pit in Abeokuta, Ogun State, South-Western Nigeria

Abstract

This study evaluated the geotechnical properties of lateritic soil obtained from the Laderin borrow pit at Oke-Ilewo, Abeokuta, Ogun State, Nigeria, with emphasis on its suitability for pavement subgrade application. Disturbed soil samples were subjected to particle-size distribution, natural moisture content, Atterberg limits, compaction and California Bearing Ratio (CBR) tests using standard geotechnical procedures. The soil contained 4.29% fines passing the 0.075 mm sieve and was classified under AASHTO as A-2-6 with a group index of zero. The liquid limit, plastic limit and plasticity index were 35.00%, 23.72% and 11.28%, respectively. The average natural moisture content was 7.12%. Standard compaction gave a maximum dry density of 1.79 g/cm³ at an optimum moisture content of approximately 12.17%. The unsoaked CBR values were 15.58% at 2.5 mm penetration and 12.88% at 5.0 mm penetration; hence, the higher value of 15.58% was adopted. The results indicate that the lateritic soil is a fair subgrade material and may be used for flexible pavement construction where adequate compaction and drainage are provided.