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Vol.1(1979) >

Please use this identifier to cite or link to this item: http://hdl.handle.net/10649/289

Title: 各種二水セッコウから製造した半水セッコウの水和特性
Other Titles: The hydration behavior of calcium sulfate hemihydvate prepared from various gypsum
Authors: 斎藤, 勝一
Authors Affiliation: 長岡技術科学大学
Issue Date: 25-Mar-1980
Publisher: 長岡技術科学大学
Journal Title: 長岡技術科学大学研究報告
Volume: 1
Start page: 104
End page: 110
Abstract: In order to examine the hydration behavior calcium sulfate hemihydrate prepared from various gypsum, compressive strength test, X-ray diffraction analysis, microscopic observation and electric conductance measurement were performed. Obtained resules were as follows: (1) Compressive strength of sample increased as standing time increased. Also, in the case of gypsum obtained from desulfurized flue gas by using the direct lime method, it reached to the saturation value after being crude for one day. (2) The X-ray diffraction analysis showed that the crystallinity of the gypsum dose not affect the compressive strength. (3) From the results of microscopic observation it was found that comparatively large crystals appear for the hydration of the hemihydrate obtained as byproduct by applying the indirect gypsum method and the direct method to the manufacturing process of phosphoric acid, and that many small needle crystals appear interwinded for the hydration of hemihydtare obtained from desulfurized flue gas and from waste water. (4) From the results of electric conductance measurement, it was found that the gypsum obtained as byproduct in the production of phosphoric acid shows lower solubility and lower hydration rate than those obtained from flue gas or waste water. This is because higher degree of oversaturation of the latter produces more crystalline nuclei of hemihydrate compared with the former.
language: ja
Contents Version: publisher
URI: http://hdl.handle.net/10649/289
ISSN: 0388-5631
Appears in Collections:Vol.1(1979)

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