Settlement Characteristics of Clayey Soils Contaminated with Petroleum Hydrocarbons

Abstract

An experimental program was undertaken to evaluate settlement characteristics of clayey soils contaminated with petroleum hydrocarbons. Four most common petroleum hydrocarbons, viz. used engine oil, diesel, gasoline and kerosene, were selected as contaminants for the study. Two types of clays, clay with low compressibility (CL) and clay with high compressibility (CH), were used in the study. Soil with low compressibility (CL) was naturally available whereas the soil with high compressibility (CH) used for the study was fabricated by mixing kaolinite and montmorillonite in the proportion 85:15 by weight. Laboratory studies for index properties and consolidation tests were conducted on virgin (uncontaminated) soil samples and soil samples simulated to varying degrees of contamination (i.e. 3%, 6% and 9% expressed as a dry weight of soil w/w) to compare the consolidation characteristics before and after contamination. The consolidation behavior of soils modified upon contamination. Larger settlement in the contaminated soil (except with kerosene oil) was due to increase in the value of compression index. The co-efficient of consolidation decreased for the contaminated soils. A modified equation to predict compression index for the contaminated soils was proposed.