Changes in Swelling Pressure and Permeability of Bentonite Caused by Ion Exchange of Montmorillonite
Permeability tests of the compacted bentonite-sand mixture using salt solutions were carried out. Exposure of the Ca type-bentonite to NaCl or KCl solutions after fully saturation with deionized water caused ion exchange of the montmorillonite. After Ca ion exchanged to Na ion, the swelling pressure of the sample increased and the permeability decreased when the low ionic strength condition, comparing with the initial value before Na ion exchange. While, after Ca ion exchanged to K ion, increase in the swelling pressure and reduction of the permeability were insignificant. K and Na ions showed the different effect of ion exchange on the engineering properties of the bentonite.
KeywordsBentonite Montmorillonite Exchangeable cation Swelling Permeability
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