Exposure of bentonite to salt solution: osmotic and mechanical effects, Discussion

Professor JimeÂnez-Salas offered me the opportunity of giving further details about my work. If I understand him correctly, Professor JimeÂnez-Salas holds that, in the tests I have conducted, exposure of the Ponza bentonite to a saturated KCl solution might have caused a partially irreversible potassium ®xation. On the other hand, I have put forward the hypothesis that such exposure caused a cation exchange that might be reversed by imposing appropriate test conditions, for instance by exposing the clay to a concentrated NaCl solution. Actually, I stressed that potassium effects are permanent under the given test conditions, and that they may be permanent under the conditions that normally occur in nature, but they are not irreversible under all conditions. Some experimental results that I have obtained in the meantime seem to conferm that potassium ions can readily be replaced by sodium ions by mass action. The phenomenon is observable, from a macroscopic point of view, under low values of axial stress