Some Geotechnical Properties of Selected Sub-Base Materials for Road Construction

Abstract

This article presents a laboratory investigation on selected soil samples in relation to their use as road construction material. Soil samples were collected from three different locations and their index, compaction properties (Optimum Moisture Content, OMC and Maximum Dry Density, MDD) were determined. Derived parameters such as activity ratio, grading modulus, plasticity product, plasticity modulus and shrinkage modulus were also determined. The California Bearing Ratio (CBR), Unconfined Compressive Strength (UCS) and the undrained shear strength (S_u) of each soil sample were determined. Models relating each of MDD and S_u to the OMC were developed. The results showed that the rating of the samples as sub-base material is fair to poor based on CBR values that range from 5 to 12% and S_u values that range from 29 to 51 kN/m².  The derived parameters also showed that the soil samples are poor construction materials with one having marginal properties. The models developed showed good correlation between both MDD and S_u and OMC based on a correlation coefficient (R²) of 0.934 and 1.000, respectively.

Keywords: California Bearing Ratio, Correlation, Derived Parameters, Lateritic Soil, Road Construction,