EFFECT OF ADSORBED ELECTROLYTES ON PROPERTIES OF MONODISPERSE CLAY-WATER SYSTEMS

• Published in: Journal of the American Ceramic Society 1940-02, Vol.23 (2), p.33-38
• Main Author: Speil, S.
• Format: Article
• Language: English
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.1940.tb14196.x

A sample of Florida kaolin was separated by a supercentrif uge into three nearly mono‐disperse systems whose sizes were, respectively, 0.1 to 0.2, 0.2 to 0.4, and 0.4 to 1.0 micron. These samples were electrodialyzed, and to aliquot samples of the H clay thus obtained, varying concentrations of sodium or barium hydroxide were added. The base‐exchange capacity at pH 7 varied linearly with the surface area. The apparent viscosity was reduced to about 4% of its original value by the addition of 1 milli‐equivalent of sodium hydroxide, after which further additions had a very slight lowering effect. The addition of electrolyte decreased the yield point and increased the maximum strain before rupture at the water content of optimum plasticity. The water of plasticity, pore water, shrinkage water, and film thickness were decreased by adding electrolyte. The dry transverse strength was doubled by the change from H clay to Na clay. Most properties varied linearly with the surface area within the experimental error. The potential concept of plasticity is briefly outlined.