Study of Index Properties of Termite-Reworked Clay Soil from Sedimentary and Basement Areas of Ondo State, Nigeria: Implications on Engineering Applications

Ikubuwaje Christopher, Obasi Romanus Ayoola

Abstract: The index properties of termite-reworked clay soil from the sedimentary and basement areas of Ondo state, Nigeria were studied. Twenty samples of the soils were collected and analyzed in the laboratory using index tests techniques. The grain size results showed a well and gap-graded inorganic clay soils with higher percentage of fines. The liquid limits (LL%) from sedimentary and basement areas vary between 33.30 and 43.56% and from 36.3 to 49.7% respectively. These variations indicate 100% inorganic soil of kaolinite clay mineral. The plasticity index (PI) varies from 11.1 to 24.3 and from 13.2 ? 24.1 for sedimentary and basement areas respectively. The soil samples were classified as CIP and A-2-4, A-2- 6, A-7-6 according to USCS, 2000 and AASHTO, 2004, systems and grouped in behaviour as V and VI for sedimentary and as CIP and CHP (A-7-5 and A-7-6) and grouped as VI and VII for basement areas respectively. These classifications and groupings portray the soils as Clay of medium to high compressibility. The studies also reviewed that the sedimentary termite reworked soil (STRWS) materials have the characteristic properties of high shearing strength and bearing capacity, presence of kaolinite clay minerals that make them highly hydrophobic. They also have low plasticity and compressibility as well as lowest swelling and shrinkage behaviour. Based on these characteristics the STRWS are more suitable for use as stabilizers in construction and for improvement in geotechnical propertie of the soils. The basement termite reworked soil (BTRWS) soil though naturally suitableas material for dam construction, they can be applied in the area of environmental engineering such as in remediation, control of erosion, as well as suitable for the manufacture of burnt bricks due to their high fines, plasticity (13.2-24.1), high compressibility and low permeability. However, both STRWS and BTRWS soils need blending laterite in order to be suitable as foundation and road construction materials.

Keywords: Index properties, liquid limits, plasticity index, Kaolinite, stabilizer.