Elegbeleye K. E., Ikubuwaje C. O.
The geomechanical properties of clay soils from the sedimentary and basement areas of Ondo State, Nigeria were studied. The moisture content, specific gravity, consistency limit, activity values, linear shrinkage and grain sizes of the collected clay soil samples were determined in the laboratory. Mean moisture contents of the two clay soil samples were 18.66 and 8.62% for sedimentary clay (SC) and basement clay (BC) indicating better shear strength for BC. The specific gravity value ranges from 2.64 to 2.73% for SC and 2.62 to 2.72 % for BC indicating similarities in mineralogical and chemical compositions. The grain size results revealed an average value of sand, silt and clay contents as 25.36, 28.94 and 45.01% for SC and 44.14, 22.88 and 31.74% for BC indicating better compaction and workability properties for BC. Linear shrinkage values were 9.58% for SC and 8.46% for BC suggesting lower swelling potential for BC. Mean plasticity index of 24.74% and 20.82% were obtained for SC and BC respectively, suggesting high compressibility and settlement for SC and medium compressibility for BC. The soil samples were classified as CI, CH and MH and A-7-6 and A-7-5 according to USCS, 2000 and AASHTO, 2004 systems and grouped in behaviour as VI and VIII for SC and as CI and A-7-6 and grouped as VI for BC respectively. It was concluded that BC has better shearing strength, compressibility, compaction and workability properties compared to SC. Though both SC and BC could find applications in engineering construction work, BC soil samples are safe and fairly competent for such work than SC. Consequently, BC is recommended as more suitable for all civil engineering works
Geomechical properties, Sedimentary Clay (SC), Basement Clay (BC), plasticity, behaviour group