Earth Sciences Pakistan (ESP)

Road construction is a critical infrastructure vital for human civilization and infrastructure. However, Nigeria is currently experiencing significant road failures across all levels of government, from federal to municipal. Among the various factors contributing to road failure are corruption and poor maintenance or supervision, but the primary reason for road failure is the quality of materials used in road construction. This research presents a laboratory study of four soil samples as material used as base and subbase in road construction. All analyses were conducted following British Standards. The liquid limit of the samples ranged from 27.1% to 29.3%, while the plastic limit ranged from 19% to 19.7%, and the plasticity index ranged from 8% to 9.65%. Linear shrinkage values were between 13.0% and 13.4%, and moisture content ranged from 10.2% to 11.2%. Maximum dry densities (MDD) varied from 2101 kg/m³ to 2144 kg/m³, with optimum moisture contents (OMC) ranging from 10.9% to 12.4%. The California Bearing Ratio (CBR) for unsoaked samples ranged from 35% to 70%, while soaked samples ranged from 27% to 56%. Due to their lateritic composition and compliance with Nigerian regulatory standards for geotechnical properties, the soils in the study area are deemed suitable as subbase materials. However, soil improvement is necessary to make them suitable for base course applications.