Premium
THE MECHANICAL MOVEMENT OF WATER THROUGH CERTAIN CLAYS AND ITS CONTROL 1 2
Author(s) -
Schurecht H. G.
Publication year - 1922
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1922.tb17896.x
Subject(s) - permeability (electromagnetism) , clay minerals , saturation (graph theory) , mineralogy , geology , soil water , water saturation , water content , geotechnical engineering , chemistry , soil science , porosity , mathematics , membrane , biochemistry , combinatorics
.—Ceramic bodies containing Georgia clay cast and release from the molds slower and have a greater tendency to crack in drying and burning than similar bodies containing English china clay. Experiments were conducted to improve these properties of Georgia clays by studying the movement of water through them and its control. Permeability .—It was found that the permeability of the clays to water was independent of the time between 2 and 10 days; that is, P is nearly constant in the formula P = W/T , in which W is the total water which has passed through and T is the time in days. This factor for North Carolina kaolin was 1.55≠.05; for English china clay 1.45≠.06; for Georgia clay 0.938≠.07; for South Carolina clay 0.673≠.07; and for Tennessee ball clay 0.64≠.08. Capillarity .—The investigation showed that the capillary rise of water through these clays may be expressed by the formula H = C h (log T ‐ 1.041) in which H is the height attained by the water in time T , and C h is approximately constant for each clay between 10 and 250 minutes, that is, it represents the movement of water through clay when it contains a certain amount of water below that required for saturation. This factor for North Carolina kaolin is 6.67≠ 0.30; for English china clay 7.30≠ 0.70; and for Georgia clay 4.66≠ 0.80. The great capillary conductivity of water through primary kaolins explains why bodies containing these get drier and release from the molds quicker than those containing secondary clays. Methods for Improving Georgia Clay .—The Permeability factor of Tennessee ball clay was increased from 0.64 to 1.20 by adding 0.7% NaOH, and that of kaolin from Dry Branch, Georgia increased from 0.938 to 1.72 by calcining to 450°C. By either, or a combination of the above treatments, it was possible to improve the properties of many Georgia clays, making them more like the English china clay in regard to permeability to water.