EFFECT OF CALIFORNIA BEARING RATIO OF SOILS USED AS SUBGRADE MATERIALS ON THE BENIN-AKURE ROAD, NIGERIA

An investigation was carried out to assess the suitability of soils brought in for use as subgrade materials Benin- Sobe axis Benin – Akure road by testing bearing capacity using California Bearing Ratio (CBR)test. The passes through four soil parent materials: - Coastal Plain Sand- CPS, Imo-Shale (IS), BendeAmaki (BA) and False Bedded or Basement Complex (FB).Soil samples were collected from profile pits based on materials. Soil also about 50 cm tarred representing subgrade. analyzed physicochemical properties Ratio. Analyses each section materials.Results obtained showed that there more failures Imo Shale,BendeAmeki a less extent Plains segment road, least material section.CBR unsoaked having highest values (14.6 16.18) 2.5 5 mm penetration test; however not significantly different other sections ( p> 0.05).The Shale poorly drained are seasonally floodedand had CBR (4.64, 5.2 readings top bottom test. Sands BendeAmeki shale but higher.Soaking did affect strength road; hence failure rate lowest.The higher soaked test, indicating which is built significant effect rates