EFFECT OF SOIL TYPES ON ROAD AS SUBGRADE

ABSTRACT

This project is an in-depth investigation of the properties of subgrade soils used in the construction of Benin-Sapele Road in Oredo Local Government Area, Edo State, Nigeria. Subgrade samples were collected at nine (9) different spot by doing auger borings examinations on the spots that are observed to have failed or are failing at about 5 and 10 meters away from the tarred road at one side. The samples were subjected to the following laboratory tests; Compaction test, California bearing ratio (CBR). The MDD range from 1.73g/cm3 to 1.82g/cm3 and OMC range from 10.2% to 13.9% respectively. Therefore, the results indicated that all the samples are sandy clay in texture according to the range of value anticipated using standard proctor test method. The CBR values for the top unsoaked and soaked samples of the subgrade soil range from 9.66% to 31.18% and 5.45% to 11.8% respectively while bottom unsoaked and soaked range from 13.30% to 34.35% and 9.17% to 26.57% respectively. Therefore, the CBR test results obtained from this study conform to Federal Ministry of Works and Housing which indicated that the subgrade sample materials are suitable for road construction except for subgrade materials collected at Jesse3, Ologbo1, Ologbo1234 and CBR5 which however can be stabilized to meet the standard requirement before being used. Hence, these data obtained from the analysis can be useful for civil engineers in the design and construction of the study area for maximum durability.