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6877374 
Journal Article 
Carbonation of gamma-Ca2SiO4 and the Mechanism of Vaterite Formation 
Saito, T; Sakai, E; Morioka, M; Otsuki, N; , 
2010 
Yes 
Journal of Advanced Concrete Technology
ISSN: 1346-8014 
JAPAN CONCRETE INST 
CHIYODA-KU 
273-280 
WOS:000283612700002 
The carbonation of gamma-Ca2SiO4 (gamma-C2S) and mechanism of vaterite formation have been investigated by evaluating the crystal structures of both gamma-C2S and vaterite. The samples used were autoclaved calcium silicate hydrate hardening bodies prepared from Ordinary Portland Cement (OPC), gamma-C2S and alpha-quartz and then subjected to accelerated carbonation. The ratio of OPC to gamma-C2S was varied. Ca2+ in both gamma-C2S and vaterite was found to be coordinated to six O2-. In addition, both gamma-C2S and vaterite have similar atomic arrangements of O2- and Ca2+ and Ca-O bond distances. Therefore, it is proposed that vaterite mainly forms from gamma-C2S via a topotactic reaction during accelerated carbonation.