Penetration of hazardous liquids through waste containment barriers exerts contamination and considerable alterations in geotechnical properties of clay liners. In general, these changes are attributed to the variation of the dielectric constant and the chemistry of the pore fluids which cause changes in soil structure. In the present study, a series of laboratory tests were performed on natural and contaminated clay soil permeated with different hazardous liquids: ethylene glycol and toluene which are generally found in petroleum-contaminated sites, possessing intermediate and low dielectric constants. Toluene was used in its pure form and ethylene glycol was used at various percentages of 0, 20, 40 and 60% by the volume of distilled water. In addition, natural sea water was also utilized as an inorganic fluid for permeation and salinization of the clay soil. The overall test results indicated that plasticity, sedimentation time, unconfined compressive strength, swell and compressibility generally decreased with increasing organic fluid/water concentration, while a slight increase in the permeability values was observed. Pure toluene resulted in diminution of plasticity and considerable flocculation of the particles which caused the soil to become granular. Sea water also caused particle flocculation and reduction in plasticity, swell potential and unconfined compressive strength, although it was noted that compressibility properties remained unchanged compared to distilled water. Finally, the correlation between the electrical resistivity and plasticity index values suggested that the electrical resistivity measurements can be used as a detecting technique for subsurface soil and waste barrier contamination.
Penetration of organic liquids through the soil causes contamination and considerable changes in the geotechnical properties of soils. In general, these changes are attributed to variations in the dielectric constant and chemistry of the pore fluids, which result in several changes in soil behaviour. For this reason, it is necessary to investigate the geotechnical properties of contaminated soils for engineering and environmental purposes. In the present study, an extensive laboratory investigation programme was carried out on a clayey soil to examine the effect of different percentages of pore fluids on sedimentation time, plasticity and shear strength of the soil obtained from Famagusta, North Cyprus. Contaminated specimens were prepared with different percentages of 0, 20, 40 and 60% ethylene glycol by volume of distilled water. Index tests were performed in order to investigate the sedimentation time and the plasticity changes in the contaminated soils. Finally, unconfined compression tests were carried out on the contaminated samples to evaluate the shear strength parameter of the soil. The results showed a decrease in sedimentation time and plasticity, and it was also shown that the unconfined compressive strength of the contaminated soils decreases with increasing percentage of ethylene glycol.
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