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Effect of Temperature and Water‐Solid Ratio on Growth of Ca(OH) 2 Crystals Formed During Hydration of Ca 3 SiO 5
Author(s) -
BERGER R. L.,
McGREGOR J. D.
Publication year - 1973
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.1151-2916.1973.tb12361.x
Subject(s) - nucleation , morphology (biology) , optical microscope , crystallography , crystal growth , isothermal process , calorimetry , analytical chemistry (journal) , crystal (programming language) , materials science , mineralogy , chemistry , scanning electron microscope , thermodynamics , chromatography , composite material , biology , genetics , physics , organic chemistry , computer science , programming language
The growth behavior, time of nucleation, and morphology of Ca(OH) 2 crystals formed during the hydration of Ca 3 SiO 5 , at 15°, 25°, and 35°C at water‐solid ratios ( w/s ) from 0.3 to 5.0 were studied by optical microscopy. In samples with w/s >0.5 growth of Ca(OH) 2 in the c ‐axis direction is initially dominant. Growth in this direction ends after a few hours, but growth perpendicular to the c axis continues for several days and produces a dendritic morphology. Growth behavior is not so well defined for w/s <0.5, in part because of the large number of unhydrated particles engulfed. Increasing temperature resulted in an increase in the number of Ca(OH) 2 nuclei and a decrease in nucleation time and crystal size. Increasing the w/s ratio improved the euhedral character of the Ca(OH) 2 crystals, decreased the number of engulfed Ca 3 SiO 5 particles, and increased the nucleation time. Dendritic morphology was most pronounced in the samples for which w/s = 1. Growth rates and the ultimate size of the Ca(OH) 2 crystals varied within a given sample. The effects of temperature and the w/s ratio on the heat evolved during the hydration were studied by isothermal calorimetry. The times of nucleation of crystalline Ca(OH) 2 estimated from calorimetry were similar to those derived from growth curves determined by optical microscopy.