Geotechnical properties of non-crystalline coastal plain sand derived lateritic soils from Ogua, Niger Delta, Nigeria

Abstract

Lateritic soils derived from coastal plain sands around Ogua, Niger Delta in Nigeria, were investigated with a view to elucidate their geotechnical characteristics, which may have influence on their engineering applications. The geotechnical properties of these soils (their compaction parameters, permeability, consolidation and shear strength) as well as index properties were investigated in the laboratory. Grain size analysis indicates that the soils are well graded with amount of fines ranging from 60% to 65%. The gravel content of the soils ranges between 2% and 3% while the linear shrinkage ranges were between 7% and 10%. The soils classify as CL soils in the USCS and in group A-7 of the AASTHO classification. The engineering properties of the soils are affected by compaction energy. However, statistical analysis shows that compaction energy has a significant effect only on the permeability coefficient. The statistical test also shows that modification such as soaking and curing have a significant effect on the California bearing ratio and unconfined compressive strength. The coefficient of permeability of the compacted soils is of the order of 1×10−7m/sec, irrespective of the compaction energy. The soils exhibit very low compressibility at all pressure ranges and show no significant lateral variation in the coefficient of compressibility. The results obtained in this study show that the lateritic soils, when compacted, are suitable for use as a fill material in embankments, dam construction and soil liners.