Effect of Inorganic Solutions on the Free Swell Index of Polymerized Clays

The usage of polymer-modified clays to construct hydraulic barriers has gained popularity due to their superior hydraulic properties. Altering the clays using polymer enhanced the chemical resistance of composite material in containing aggressive inorganic solutions to which the untreated virgin clays fail. The present study is focused on evaluating the free swell index of clays modified through the in situ polymerization of acrylic acid. Tests were conducted on two mineralogically diverse clays, i.e., Na-bentonite and kaolinite, using interacting liquids such as NaCl, CaCl2, AlCl3, and solutions with extreme pH conditions. The swell index of polymerized clays was in the order of monovalent > divalent > trivalent solutions and was higher than the swell index of the untreated clays. Test results showed that the polymer addition had improved the swelling capacity of clays. However, hydraulic conductivity tests are needed to be performed to ascertain their long-term hydraulic performance.