Investigating the Effect of Diesel Pollution on Marl Parameters-A case study in Qom City

Document Type : Research Note

Authors

1 University of Qom

2 Civil Engineering Department, University of Qom, Iran

Abstract

Considering population growth, industrialization, and pollutant sources, soil contamination by hydrocarbon is one of the most significant risks to humans. Besides its adverse environmental effects, soil pollution also alters the geotechnical properties of soils. Soils around refineries, fuel stations, and oil and gas pipelines, especially in oil-rich countries like Iran, are constantly exposed to contamination due to the extensive transportation of hydrocarbons. Given the prevalence of marl soil in Iran, particularly in Qom city, studying the properties of contaminated soil is crucial for various engineering purposes. Despite various methods for bioremediation of contaminated soil, these methods have limitations. Therefore, a detailed study of the geotechnical behavior of hydrocarbon-contaminated soil and its potential use for civil and economic projects is essential. In this study, we investigated the impact of diesel pollution on the strength and consolidation parameters of Qom’s marl soil using uniaxial and consolidation tests, along with electron microscope images. For this purpose, marl soil samples were prepared with 0%, 3%, 6%, and 9% diesel contamination by weight and tested at different time intervals (0, 7, 14, and 28 days). The results of the uniaxial compressive strength test indicate that the marl sample increases by approximately 68% with 3% pollutant content, but with further pollutant increase, the compressive strength decreases. The effect of time also manifests as a reduction in strength for contaminated samples. On the other hand, consolidation test results show that pollution leads to an increase in the compression index and swelling in marl soil. The coefficient of consolidation also follows a decreasing trend with increasing pollutant content. Additionally, electron microscope images reveal reduced porosity and increased cohesion in the contaminated sample compared to the 7-day diesel-polluted sample. Moreover, a linear relationship with a correlation coefficient of 0.73 was obtained between the compressive strength and the secant modules.

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