Effect of Fly Ash on Geotechnical Properties of Oil-Contaminated Soil

Abstract

Accidental oil spillage or leaking has caused severe damage to the environment. Oil contamination can adversely affect the soil microbes and plant as well as contaminate groundwater resources for drinking or agriculture. Hydrocarbon contamination will not just affect the quality of the soil but will also alter the physical properties of oil-contaminated soil, excessive settlement of tanks and breakage of pipeline. Contamination changes the behaviour of soil and also alters its engineering properties leading to several problems like loss in strength, differential settlement and cracks in existing foundation or structure. For any possible applications of contaminated soils, knowledge of the geotechnical behaviour of contaminated soil is required. The experimental programme was carried out in the present study to know the effect of diesel oil contamination (4, 8 and 12%, by dry weight) on geotechnical properties of locally available fine-grained soil and the efficacy of fly ash as a stabilizing agent at different percentages 20, 40 and 60% (w/w). The results show that the consistency limits and the strength parameters have been affected marginally due to contamination. The utilization of industrial by-products such as fly ash is of increasing importance as an option for stabilizing contaminated sites due to its pozzolanic nature and also in view of minimizing the environmental impact. The plasticity index of stabilized soil was observed to be not uniform with the increase in fly ash addition. The compaction characteristics, Unconfined Compressive Strength (UCS) and CBR value of soil decreased with the addition of contaminant and it regains marginally with the addition of fly ash. UCS and CBR values showed an increase of 29.5 and 73.5% with an addition of 60% fly ash. The results from the study may be beneficial for the engineers and researchers in reusing the contaminated soils for safe and economic construction of structures.