Pore Fluid Chemistry and Aging Effects on Swelling, Shear Strength, and Pore Size Distribution Behavior of Soils

Investigation of aging effect is important due to examination of long-term influence of contaminants on the landfill liners. The effect of Na⁺ and Ca²⁺ ions on the engineering behavior of soils were examined and the aging effect on engineering properties of kaolin and bentonite samples in the presence of ions were observed. The pore size distribution, swelling and shear strength parameters were determined under the same conditions after approximately 60, 190 (shear strength), and 250 (swelling) days. There is no difference at the swell index values of kaolin in the presence of DI water and 0.5 M NaCl. However, Ca²⁺ ions decreased the swell index of the kaolin sample. In the presence of Na⁺ ions, there is no difference at the swell index values of the bentonite sample. However, in the presence of Ca²⁺ ions, swell index decreased from 0.035 to 0.029. During aging, the reverse effect occurs at bentonite sample when compared with kaolin sample. It is expected that, as aging progresses, bonds between particles increase; therefore, the swell index of the soils decrease. However, the results of this study have shown that this is not true for bentonitic samples. When the results of 0 day, 60 and 190 days samples were compared, the \xQ' values of kaolin and bentonite samples decreased by time.