Composition, Engineering and Industrial Significance of Soil Deposits along Major Highways in Ondo State, Nigeria

Abstract

Geochemical and geotechnical studies of soil deposits along some highways in Ondo State were investigated. Field mapping revealed an underlying basement rock suite comprising granite, granite gneiss, migmatite and schist. The geochemical analysis employed X-ray fluorescence and Atomic Absorption Spectrophotometer (AAS) to determine the major and minor oxide geochemistry while particle size analysis test, Atterberg limit test, compaction test, specific gravity, triaxial compression test and California bearing ratio were determined following the British Standards (BS-1337). Abundances of major elements show a predominant  (43.4–61.30%),  (18.30–33.70%) and  (14.50–23.28%) constitute over 95% of the bulk chemical compositions. Other constituents include and The silica:sesquioxide ratio  of the soil shows that all sampled soil are true laterite except samples AL-1 and AF-1 (are lateritic) which correspond to samples taken from sites 1 and 3 respectively. However, the soils satisfy Federal Ministry of Works and Housing of Nigeria and AASHTO recommended standard for subgrade and subbase/base foundation construction materials, but samples AL-3, OF-2, and OF-4 need to be graded with sand or gravel to reduce its plasticity, while only sample AL-2 can serve as base course material for highway construction. It’s concluded from the results that the tested soils have more engineering applications than industrial usage since only samples from sites 1 and 3 can serve as ceramic material and brick clay provided the alumina and iron contents are reduced.  The soils in their raw state, may not be able to serve as fillers and coating materials in the paint and cosmetic industries, generally due to an amount of sand in the samples (above 50%), which makes them unsuitable.