Geotechnical Properties of Offa Lateritic Soils and its Suitability as Subbase and Base Materials

Abstract

The determination of the suitability of the base, subbase and subgrade materials are important in road construction. This study evaluate the geotechnical properties of Offa lateritic soils and its suitability for use as subbase and base materials. The index properties, compaction, CBR and coefficient of permeability were conducted on the lateritic soils from the pits. The results revealed that the SG of the soil from the pits are within the specified range for lateritic soil. The NMC of pits A to D, conform to specified limit for road constructions while sample E does not conform to the specified range. The soils from pits A and B; and C and E, fall under group A-6 and A-7-6, respectively, while soil from pit D fall under group A-2-7. Soils from four pits are within the specified limit for LL while soil from one pit is above the limit. The CBR value of WAS shows that lateritic soils from three pits are suitable for use as subbase materials while lateritic soils from two pits are suitable for use as base materials. Lateritic soils from four pits under the AASHTO unsoaked are suitable for use as base materials, whereas only soils from one pit are suitable for use as subbase materials. However, all lateritic soils from under BS are suitable for use as subbase materials. The results of this study will be useful for road construction in Offa and its environs, thereby serving as guide for future road pavement design.