Malaysian Journal of Geosciences (MJG)

The qualities of road construction materials are essential in their choice for various civil works. Therefore, engineering geological properties of the sub-soil that constitute sub-grade materials along Supare- Emure road were investigated in order to determine the causes of the failure of the pavement along the unstable sections. A total of twelve (12) sub- grade soil samples were collected from unstable and stable sections of the road and were subjected to various geotechnical tests. These tests include natural moisture content, atterberg limits, linear shrinkage, plasticity index and grain size. Results showed that the natural moisture content of the stable sections range from 5% to 11%, while those of unstable sections range from 23.8% to 37.2%. The range of the unstable sections fell short of required specification. For the plasticity index, both sections have values less than required 30%, while the unstable sections had linear shrinkage above 8%. On the grain size results, unstable sections have values greater than the specified 35% passing. Bedrock chemistry and clayey nature of sub-grade soils have been found to be responsible for the failed sections of the road investigated..