The Effect of Sodium Chloride Solution on Swelling, Compressibility and Permeability of Bentonite

Saline sea water، groundwater into salt domes or municipal waste leachate can affect hydro-mechanical properties of bentonite as a sealing material in nuclear waste repositories or landfills. This paper investigated the effect of sodium chloride solution on Atterberg’s limit، swelling، consolidation and permeability of bentonite. Swelling and consolidation test had been done at 0. 05، 0. 1، 0. 5 and 2 molar solution and pure water by oedometer apparatus in Iran University of Science and Technology. Considering the results، it can be seen that a little increase in concentration of the solution reduces swelling of bentonite. So that the swelling potential of bentonite reduced from about 82% to about 1. 5% by increasing in concentration of the solution from pure water to 2 molar solution. Liquid limit and plastic index of bentonite were reduced by increasing concentration of the solution but plastic limit was not changed significantly. Meanwhile increased concentration of the solution will facilitate reaching equilibrium for swelling and consolidation of the samples which occur due to their enhanced permeability. Permeability of bentonite increased about 7 times by increasing in concentration of solution from pure water to 2 molar solutions. Also، the Compressibility of bentonite was reduced by increasing in concentration of sodium chloride in the solution.