雪硅钙石
硅酸盐
水合硅酸钙
硅酸钙
结晶学
相(物质)
二聚体
晶体结构
离子
水合物
四面体
钙
化学
材料科学
矿物学
热力学
有机化学
物理
水泥
冶金
复合材料
出处
期刊:Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
[Wiley]
日期:2014-11-07
卷期号:70 (6): 903-923
被引量:357
标识
DOI:10.1107/s2052520614021982
摘要
C-(A)-S-H(I) is a calcium silicate hydrate that is studied extensively as a model for the main binding phase in concrete. It is a structurally imperfect form of 14 Å tobermorite that has variable composition and length of (alumino)silicate anions. New structural-chemical formulae are presented for single- and double-chain tobermorite-based phases and equations are provided that can be used to calculate a number of useful quantities from (29)Si NMR data. It is shown that there are no interlayer calcium ions when the silicate chains are of infinite length and that one is added for each tetrahedral `bridging' site that is vacant. Preparations that have Ca/Si greater than about 1.4 include an intermixed Ca-rich phase. It is not possible to generate a structural model for a dimer that is crystal-chemically consistent with known calcium silicate hydrates if the starting structure is an orthotobermorite, i.e. of the type that has been used in all previous studies. Crystal-chemically plausible models are developed that are based instead on clinotobermorite. A number of models that represent different mean chain lengths are developed using crystal-chemical and geometrical reasoning. The models account for experimental observations, including variations in Ca/Si, H2O/Si, (alumino)silicate anion structure and layer spacing.
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