Influência da salinidade do fluido percolante sobre a permeabilidade de solos argilosos

Abstract

The study evaluates the influence of percolating fluids with different NaCl concentrations on the permeability of clayey soils, a key parameter for geotechnical and environmental engineering applications. The research is justified by the need to understand variations in hydraulic conductivity when the chemical composition of the percolating fluid differs from distilled water, which is commonly used in laboratory tests but does not always represent actual field conditions. The methodology involved the geotechnical and mineralogical characterization of two clayey soil samples through granulometry, specific gravity, Atterberg limits, compaction, and permeability tests. The mineralogical characterization was performed using the X-ray diffraction (XRD) technique. Permeability tests were conducted using distilled water and saline solutions with NaCl concentrations of 5, 10, 15, and 20 g/L. The results showed that the hydraulic conductivity of clayey soils decreases with increasing salt concentration in the solution. This effect is attributed to the expansion of the diffuse double layer and the consequent dispersion of clay particles, leading to a reduction in pore voids and, consequently, lower water flow. It was observed that, for both soils with the same clay mineral (kaoliniteillite), this reduction in permeability was more pronounced in the soil with a higher clay content.