Ceramics-Silikáty 35, (2) 121 - 126 (1991)

Swelling (or sedimentation) volumes (SV) of materials prepared by treating fine fractions of bentonites from Jelšový Potok (Czechoslovakia). Clay Spur (Wyoming, USA), and Belle Fourche (South Dakota, USA) with HCl were stabilized by the subsequent treatment with sodium salt (NaCl, NaNO₃ or Na₂SO₄) solution. The anions of these salts had negligible effect on the SV. Lower SV achieved after HCl + Na₂CO₃ treatments are supposed to be caused by the reaction of surface protons and CO₃²⁻. Only moderate differences in the SV were found between the sodium salt treated samples without previous HCl treatment. That confirms no negative effect of Na₂CO₃ alone on the SV. High SV achieved with the HCl treatment were not achievable without it.