Influence of pore fluid composition on volume change behaviour of clays exposed to the same fluid as the pore fluid

This paper reports experimental results relative to the influence of pore fluid composition on volume change behaviour of four different clayey soils: the Ponza bentonite, a commercial kaolin, the Bisaccia and the Marino clays. Oedometer tests were carried out on dry materials and on the materials reconstituted with distilled water, concentrated NaCl solutions and a non polar fluid (cyclohexane). The influence of ethanol was analysed only in the case of the Bisaccia clay. All the tests were carried out by exposing the soils to the same fluid as the pore fluid. The results show that the materials prepared with cyclohexane behave similarly to the dry ones and they both are less compressible than the materials prepared with aqueous solutions. The coefficient of consolidation increases dramatically and swelling is negligible in the whole considered stress range. Volume change parameters strongly depend on the dielectric constant of the pore fluid.