EFFECTS OF USED MOTOR OIL ON THE ENGINEERING PROPERTIES OF LATERITIC AND CLAYEY SAND MATERIALS IN NIKE, ENUGU EAST L.G.A., ENUGU STATE, NIGERIA

ABSTRACT

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.

CHAPTER ONE

INTRODUCTION

1.1 PREAMBLE

Engine oil or motor oil is derived from petroleum based compounds which consists mainly of hydrogen and carbon. Thus, engine oil is a hydrocarbon compound. Used motor oil can be dispersed into the soil in four different ways: escape and loss of oil during motor operations; applications on rural roads for dust control, during asphalting with asphalt-containing waste crankcase oil, and finally, when it is placed directly on landfills or at the mechanic workshops. The release of used engine oil on soil poses a big threat to engineering structures. Apart from engineering structures, soil microbes and plants as well as contaminate groundwater resources for drinking or agriculture may also be contaminated (Hong et al, 2010). Used motor oil is a very dangerous polluting product, it contains polynuclear aromatic hydrocarbons (PAH’s) and high levels of heavy metals, PAH’s are dangerous to health because some are known to be mutagenic and carcinogenic, benzo[a]pyrene are well known for their high carcinogenicity(IRAC, 1983; Raphael 1989).

Used motor oil contaminations of soil are common wherever motor mechanic workshops are located. It has been reported that the bearing capacity of such soils is drastically reduced and made engineering structures unsuitable to run, or plant growth by reducing the availability of nutrients or by increasing toxic contents in the soil (Euchun and Braja, 2001). Mechanic workshops are seen at every point in town and developing areas (Fig. 1); some well-known mechanics have occupied a piece of land for more than 10 years. The oil from vehicles are disposed carelessly, sometimes the oil is drained from the vehicle and collected in a container and are disposed at a particular point on the land but most times released directly from the vehicle to the ground. Cases have been witnessed where individuals or even the government reclaims a piece of land that was formally used as a mechanic workshop and structures are erected on it.

The essence of this research is to examine the influence of used engine oil on the engineering properties of lateritic and clayey sand materials.

Hydrocarbon contamination will not just affect the quality of the soil but will also alter the physical properties of oil contaminated soil. This will lead to geotechnical problems related to construction or foundation structure on this oil contaminated sites (Mackenzie, 1970). This implies that care should be taken in the disposal of hydrocarbon compounds. But unfortunately, an average Nigerian do not care how the bad oil from his vehicle is being disposed, all he cares is that the oil has been drained from his vehicle to prevent damage to it (vehicle).