H Mortezaei - University of Guilan, Rasht, Guilan, Iran
M Karimpour-Fard - University of Guilan, Rasht, Guilan, Iran

Clayey soils are the most common material used in waterproofing and play an essential role in waste and contaminationcontrol. Permeability is a key parameter in such problems and its determination is needed in ensuring the satisfactoryperformance of the soil. Research has shown that a permeant fluid with a low dielectric constant can shrink the doublelayer around the clay particles which will, in turn, increase the permeability of the soil. In this paper, the permeability oftwo types of clay with different plasticity, exposed to the flow of water and methanol as polar and miscible solvents andgasoline and car oil as non-polar and immiscible solvents is investigated. In addition, the effect of soil properties such asplasticity and compaction water content on permeability of the samples is examined. To this end, soil samples are preparedand compacted at various water contents. Then, permeability tests are conducted according to the modified constant headmethod and the effects of parameters such as the fluid dielectric constant, water content of the samples and soil plasticityare examined. The results demonstrate that the lower dielectric constant of the organic fluid decreases the thickness of thedouble layer, providing more space for the flow of the permeant and as a result, the permeability of the clay increases. Thereduction of the permeant dielectric constant from 80.4 to 2.28 led to a remarkable increase in soil permeability.

Clay; Dielectric Constant; Organic Fluid; Permeability; Water Content