α-Dicalcium silicate hydrate: Preparation, decomposed phase, and its hydration

Hideki Ishida, Satoru Yamazaki, Kaori Sasaki, Yoshihiko Okada, Takeshi Mitsuda

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)

Abstract

α-C2SH can be synthesized by hydrothermal treatment lime and silicic acid for 2 h at 200 °C. When heated to 390-490 °C, α-C2SH dissociates through a two-step process to form an intermediate phase plus some γ-C2S. 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. 29Si 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-C2S 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-C2S at the lowest temperature.

Original languageEnglish
Pages (from-to)1707-1712
Number of pages6
JournalJournal of the American Ceramic Society
Volume76
Issue number7
Publication statusPublished - 1993 Jul

ASJC Scopus subject areas

  • Ceramics and Composites

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