Effects of contamination with gasoline on engineering properties of fine-grained silty soils with an emphasis on the duration of exposure

Abdollah Yazdi,Ebrahim Sharifi Teshnizi

doi:10.1007/s42452-021-04637-x

Abdollah Yazdi, Ebrahim Sharifi Teshnizi

Open Access

https://doi.org/10.1007/s42452-021-04637-x

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Abstract

Leaking tanks may lead to severe contamination of their surrounding soil. The geotechnical behavior of the soil varies with the physicochemical processes that occur between the contaminant and the soil. In this respect, studying the geochemical properties of gasoline-contaminated soils and sediments seems to be important for engineering and especially environmental purposes. In this paper, laboratory tests were carried out to examine the effects of crude gasoline contamination on some of the geotechnical properties of a silty soil sampled from the Mashhad plain, located in the northeast of Iran. Tests consisted of basic properties, Atterberg limits, compaction, direct shear, and uniaxial compression tests, which were carried out on clean and contaminated soil samples at the same densities. The contaminated samples were prepared by mixing the soils with crude gasoline in the amounts of 3%, 6%, 9%, and 12% of dry weight and curing periods of 0, 7, 15, and 30 days. Results indicated a decrease in the friction angle and an increase in the cohesion of the soil by increasing gasoline content. Besides, a reduction in the maximum dry density and optimum moisture content was observed in the compaction test. The increase in gasoline percentage up to 6% also showed a direct effect on increasing the liquid limit and plastic limit of silty soil, which decreased thereafter. Moreover, any increase in gasoline percentage had a reverse effect on the modulus of elasticity of the soil. The increase in gasoline percentage up to 3% also had a direct impact on the uniaxial compressive strength of the soil, exceeding which it started to decline. Finally, the effects of contamination duration were examined by testing contaminated samples in periods of 7, 15, and 30 days under natural conditions. The results showed a reverse relationship with all geotechnical properties due to aging and a reduction in the gasoline content due to the evaporation of volatile compounds. Also, the numerical analysis of the laboratory results indicated an increase in settling and the percentage of shear strain beneath the foundation with increasing the contamination level, confirming the laboratory results.

Highlights

Human life depends highly on energy sources, especially fossil fuels such as oil, gas, and gasoline
Due to the topographic conditions of this area, most of the observed sediments are of silty type (Fig. 1). In this region, some oil refinery and petrochemical industries related to gasoline storage are under construction
The initial increase in unconfined compression test (UCT) of the sample with 3% gasoline could be attributed to the formation of flocculation fabric because of the contamination (Fig. 10)

Summary

Introduction

Human life depends highly on energy sources, especially fossil fuels such as oil, gas, and gasoline. Unlike very low environmental consequences of clean energies, hydrocarbons can alter the environment such as soil and rock [1,2,3,4]. Soil contamination by petroleum products has been intensified due to human activities. In this respect, several techniques such as refining to acceptable standards have been considered for dealing.

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