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α‐Dicalcium Silicate Hydrate: Preparation, Decomposed Phase, and Its Hydration
Author(s) -
Ishida Hideki,
Yamazaki Satoru,
Sasaki Kaori,
Okada Yoshihiko,
Mitsuda Takeshi
Publication year - 1993
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.1151-2916.1993.tb06638.x
Subject(s) - silicate , crystallinity , phase (matter) , hydrate , calcium silicate , hydrothermal circulation , mineralogy , silicic acid , calcium silicate hydrate , chemistry , tobermorite , raman spectroscopy , materials science , crystallography , analytical chemistry (journal) , inorganic chemistry , chemical engineering , metallurgy , organic chemistry , cement , engineering , composite material , physics , optics
α‐C 2 SH can be synthesized by hydrothermal treatment of lime and silicic acid for 2 h at 200°C. When heated to 390–490°C, α‐C 2 SH dissociates through a two‐step process to form an intermediate phase plus some γ‐C 2 S. This appears to be a new dicalcium silicate different from known dicalcium silicates—α, α′ L , α′ H , β, and γ phase—and is stable until around 900°C. At 920–960°C, all the phases are transformed to the α′ L phase. The intermediate phase has high crystallinity and is stable at room temperature. 29 Si MAS NMR measurements indicate the possibility that it contains both protonated and unprotonated monosilicate anions. The intermediate phase that has passed through the α’phase at higher temperature yields β‐C 2 S on cooling. The intermediate phase is highly active, and completed its hydration in 1 day ( w/s = 1.0, 25°C). Among the crystalline calcium silicate hydrates with Ca/Si = 2.0, it is hillebrandite that yields β‐C 2 S at the lowest temperature.