By Akagha, Franklin Uchechukwu
Used motor oil is constantly disposed indiscriminately at mechanic workshops in Nigeria without considering its impact to the soil and the environment at large. This work investigates intrinsic changes in the engineering properties of lateritic and clayey sand materials. Soil samples were collected at the depth of 30cm and were then air dried at room temperature for seventy two (72) hours. After air drying, the lateritic material was divided into five equal parts. Each of the samples was artificially contaminated with 4%, 6%, 8%, and 10% of used motor oil; the last uncontaminated portion was used as the control sample. This same procedure was carried out on the clayey sand material. These materials were kept in an air tight polythene bag for fourteen (14) days to enable the mixture to cure. Samples were subjected to mechanical analysis, specific gravity, permeability, Atterberg limits, compaction and triaxial tests. Results revealed that specific gravity of the samples decreased with increase in used motor oil from 2.66 – 2.25 in lateritic soil and 2.72 – 2.35 in clayey sandy soil, permeability also decreased with increase in the percentage of used motor oil, 2.75 – 1.85 cm/sec in lateritic soil and 1.97 – 1.70 cm/secin clayey sandy soil, maximum dry density(MDD) and shear strength of the samples also decreased with increased percentage of used motor oil in both the lateritic and clayey sand samples. This research shows that used motor oil reduces the shear strength of the soil.