Geotechnical Properties of Some Clay Deposits in Some Parts of Southwestern Nigeria in Relation to Its Engineering Implications on Constructions

Abstract

Twenty-two clay samples from Oduna, Okada, and Etsako clay deposits in Southwestern Nigeria were subjected to Geotechnical analysis to evaluate their impact on engineering, especially on construction. The results revealed that the clays deposits were majorly fine-grained texture (<60%), with Plasticity ranging from 23% to 121%, Liquid Limit (25%~205%) having plasticity of medium to very high with a specific gravity from 1.93 to 2.58. Using the American association of state highway and ransportation office (AASHTO) and Unified system classification scheme (USCS), the samples fell within A-7-6 (clayey soil) indicating a subgrade that is fair to poor and within the CL-CH category of fine-grained soil with medium to very high plasticity. Compaction having maximum dry density (MDD) to optimum moisture content (OMC) ranges from 0.94 g/cm3 ~1.68 g/cm3 to 11.9%~44.5%, Triaxial result with cohesion between 0.33~35 and shear strength from 44~120 and California bearing ratio for unsoaked bottom 7.52~40, top 4.82~39.18 and soaked bottom 2.89~30.41, top 4.21~33.53. The geotechnical properties of the clay deposits do not meet the standard requirement hence the implication in engineering might be susceptibility to construction failures.