A mixture of CaO and silicic acid prepared with a Ca/Si ratio of 2.0 was hydrothermally synthesized at 80° to 200 °C, and the thermal decomposition behavior of the products (C-S-H with Ca(OH)2) was analyzed using XRD, 29Si MAS NMR, and the trimethylsililation method (TMS). It was found that the main silicate anion structure of C-S-H was a mixture of a dimer and a single-chain polymer (larger than Si5O16) and that polymerization advanced with an increase of the synthesizing temperature. On heating, the products decomposed to form β-C2S. It was found that the decomposition was gradual and that the higher the temperature of hydrothermal synthesis, the lower was the temperature of the decomposition into β-C2S. Although the decomposition proceeded to form a monomer (β-C2S) from the polymer and dimer, this dimer was resistant to heat and did not decompose unless heated to above 400 °C.
|Number of pages||5|
|Journal||Journal of the American Ceramic Society|
|Publication status||Published - 1994 May|
ASJC Scopus subject areas
- Ceramics and Composites