The influence of geological factors on the engineering propertise of some western Nigerian residual lateritic soils as highway construction material
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Date
1985
Authors
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Journal ISSN
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Publisher
Obafemi Awolowo University, Ile Ife, Nigeria
Abstract
The fundamental influence of geology on some geotechnical properties of lateritie soils as
highway -construction material within a restricted macroclimatic area of Akure and llesha in the
deciduous rain forest belt of South Western Nigeria was investigated.
Lateritic soils derived from four major petrological units, namely t'.aarse, P~yrphyrit.ie Granite,
Coarse to medium Charnockite, Coarse to medium massive amphibolite, and medium Grained
Talc Schist were concentrated upon the different ways in which Geochemistry, Clay Mineralogy,
Degree of weathering and Laterization influenced the engineering properties of the sails were
examined.
The results have conclusively proved that geology is the main factor controlling the geotechnical
properties of residual lateritic soils within the restricted climatic environment. A new parameter,
termed the water absorption coefficient of lateritic soils was evolved. It is the angular
relationship between the 48-hour soaked CBR value of a soil and average percent value of the
soils' CBR at Optimum Moisture Content of Modified AASHO acompaction. The mean values
of the coefficient in the four soils studied showed discernible relationship to the respective parent
rocks.
Recommendations for further research include an investigation of the relationship between the
shear strength parameters of compacted genetic lateritic soils especially in the triaxial test: and
the relationship between the water absorption coefficient and the geophysical resistivity values of
similarly compacted genetic lateritic soils. Such subsequent research may eventually provide
convenient quantitative engineering parameters which would relate the variations of moisture
content, dry density, geophysical resistivity and the triaxial shear strength values in genetic
lateritic soils in general.
Description
202p
Keywords
Soils, Lateritic soils, Geology, Macroclimatic area, Rain forest, Geochemistry, Moisture, Absorption coefficient, Tri-axial test/ geophysical resistivity