The Influence of Temperature and Nature of CaO Component on the Formation of α-C₂SH

Abstract:

In this work hydrothermal synthesis was carried out at 175 and 200 °C for 2, 8, 16, 24 and 48 h when using a stoichiometric composition (CaO/SiO₂=2.0) mixtures consisting of amorphous SiO₂·nH₂O and CaO or Ca (OH)₂. It was determined that α-C₂SH forms only after 16 h of the hydrothermal synthesis at 175 °C when using CaO. It starts to recrystallize to hilebrandite after 48 h. The temperature increase to 200 °C vividly fastens the formation of α-C₂SH as a noticeable amount of this calcium silicate hydrate was identified in the product already after 2 h and it became the dominant compound after 8 h. In case of using Ca (OH)₂, only negligible traces of α-C₂SH were identified after 2 h and the growth of its amount in the product, while prolonging the synthesis, was much slower as it prevailed only after 16 h. In addition, considerable amounts of unreacted portlandite were identified in the product even after 48 h.

• Periodical: Solid State Phenomena (Volume 244)
• Pages: 12-18
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.244.12
• Online since: October 2015
• Authors: Rokas Gendvilas*, Raimundas Siauciunas
• Keywords: Hydrothermal Synthesis, SEM, XRD, α-C₂SH

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