Specific Gravity of the Eocene Sediments of Ameki Formation, Niger Delta Basin, Nigeria. Case Study: Okpanam, Southern Nigeria.

Abstract

Specific gravity is the ratio of the mass of soil solids to the mass of an equal volume of water. It is an important index property of soils closely linked with mineralogy and/or chemical composition. It decreases with aluminium content but increases with iron content and grain size fraction. For the disturbed samples, the samples were collected at 0.5m and for the undisturbed samples, they were sampled at 1.0m intervals. If numerical values are given in a discussion where it may not be clear to what the specific gravity is referred, the magnitude of the values may indicate the correct usage since the of the soil particles will always be larger than the bulk specific gravity based on the soil voids in the computation {and either full of air (dry) or full, or partly full of water}. The results show the value of the specific gravity of de-aerated soil samples across the ten trial pits. The disturbed soil samples had a range of 2.59 - 2.87 with a mean on 2.68 while the undisturbed soil samples had a range of 2.61 – 2.87 with a mean value 2.67. Based on mineral contents found in sediments, the soils are majorly composed of quartz (2.65) and of feldspar (2.65 – 2.7). These results in the soil samples classified as sand, silty sand, inorganic clay and soils containing Mica or Iron. Other geotechnical index properties such as density index, consistency limits, particle size gradation, compaction, consolidation, permeability, shear strength help in stability of engineering structures on or below the earth.