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Character of Hydration of 3CaO.Al 2 O 3
Author(s) -
FELDMAN R. F.,
RAMACHANDRAN V. S.
Publication year - 1966
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.1151-2916.1966.tb13255.x
Subject(s) - hydrate , hexagonal crystal system , crystallography , materials science , mineralogy , epitaxy , chemical engineering , reaction mechanism , porosimetry , layer (electronics) , chemistry , porosity , nanotechnology , catalysis , composite material , porous medium , organic chemistry , engineering
The C 3 A compacts were hydrated and the reaction was studied by DTA, X‐ray diffraction, mercury porosimetry, and volume change analysis. The hexagonal hydroaluminates C 2 AH 8 and C 4 AH 19 formed at 2°, 12°, and 23°C by a direct mechanism between C 3 A and H 2 O. The hydration reaction at 52° and 80°C was stopped by formation of C 3 AH 6 around the C 3 A grains. The rate of conversion of the hexagonal hydrates to cubic C 3 AH 6 increased with temperature. Volume change analysis confirmed that C 3 AH 6 grows epitaxially on the surface of the C 3 A grain. The reaction at this surface and the passage of water through the layer of hexagonal hydroaluminates control the overall reaction rate. The conversion of the hexagonal hydrates to C 3 AH 6 accelerates the reaction by removing the layer of products from around the C 3 A grain by a solution mechanism. At 52° and 80°C, C 3 AH 6 may form without the intermediate formation of the hexagonal hydrate.