CORRELATION BETWEEN LABORATORY CONE PENETRATION AND CALIFORNIA BEARING DYNAMIC RATIO OF SOILS IN EKITI CENTRAL SENATORIAL DISTRICT

This research was aimed to analyze and determine the correlation between laboratory dynamic cone penetration (DCPT) and California bearing ratio (CBR) of soils in Ekiti central senatorial district. Twenty soil samples were collected randomly from five (5) different local government areas that made up the senatorial districts with their respective locations taken with GIS software which were represented with “sample codes EK1 to EK20”. The soil samples were subjected to various laboratory tests to determine their geotechnical properties, which includes; the Natural Moisture Content (NMC) test, Specific Gravity (GS) test, Particle size distribution test, Atterberg Limit test, Compaction test, California bearing ratio and Dynamic cone penetration test. The tests results show the sample natural moisture content (NMC) values ranges from 3.22% to 92.13%, Specific gravity ranges (GS) from 2.05 to 3.60, the liquid limit (LL) ranges between 26.40% and 54.20%, the plastic limit (PL) between 16.77% and 31.43%, the linear shrinkage (LS) between 3.57% and 16.00% and plasticity index ranges between 6.02% and 25.66%, the sample ranges from A-2-6 to A-7-6 (good to fairly poor soil), the groups of soil ranges between SC( coarse grained, sand, sand with fines), and CL( fine grained, silt and clay, inorganic). Optimum Moisture Content (OMC) ranged from 11.80% to 18.00%, Maximum Dry Density (MDD) of the sample varied between 1492 and 2090kg/m3, CBR results values after 24hours of soaking ranges from 8.50% to 39.0%, In DCPT the number of blows ranges from 1.0 to 7.0, the penetration index ranges from 0.200mm to 1.400mm. Hence “sample EK2, EK13, EK14, EK15, EK16 and EK20 evolved to have the most suitable characterization for civil engineering works when classified with AASHTO. The modelling regression shows that the correlation between the two test CBR and DCPT is partial prediction (0 ˂ R2˂ 1) and a very weak relationship (R2˂0.2). The results indicate that DCPT can be used as a reliable alternative to CBR for certain soil types, offering advantages in term of reduced testing time. The findings of this study contribute to the development of more efficient and cost-effective geotechnical characterization methods, benefitting infrastructure development projects.