PERMEABILITY AND GRAIN-SIZE CHARACTERISTICS OF SAGAMU AND IBADAN-TOLL-GATE LATERITIC SOILS IN SOUTHWESTERN NIGERIA

¹S. O. Idowu, ²G. O. Adeyemi and ³S. S. Dada

^1&3 Department of Earth-Sciences, Salem University, Lokoja, Nigeria.

²Department of Geology, University of Ibadan, Ibadan, Nigeria.

ABSTRACT

Permeability and grain-size tests were performed on three samples each from two locations to provide direct as well as indirect measures for highway failure. All samples tested show a significant degree of permeability with low volume of fines [average value of] for soils developed over Ibadan basement complex, while those of Sagamu sandstone show a high proportion of fine materials of with low flow gradient rate. Comparing these parameters with the values obtained from compacted soils, the grain sizes and gradient flow, the Sagamu samples show a significant increase in the proportion of fines, over that of Ibadan. Applying these data to highway geotechnics, the flexibility characteristics of low permeability terrains can be checked provided fluid flow especially out of the sediments is not impeded and can therefore solve susceptibility of shear failure.

Keywords: permeability, grain-size, highway-geotechnics Sagamu-Ibadan, Shear-failure