Ceramics-Silikáty 53, (2) 81 - 87 (2009) |
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FORMATION AND STABILITY OF C–S–H(I) IN Ca(OH)₂/CaO–THERMAL SILICA DENSIFIED–H₂O SYSTEM
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Baltakys Kestutis 1, Jauberthie Raoul 2, Kasperaviciute Vita 1
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1 Department of Silicate Technology, Kaunas University of Technology, Radvilenu 19, LT – 50270 Kaunas, Lithuania
2 Department of Civil Engineering, INSA, 20 Av. des Buttes de Coësmes, CS 14315, 35043 Rennes, France
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Keywords: Calcium silicate hydrates, C–S–H(I), Xonotlite, X-Ray Diffraction
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The stability and crystals morphology of C–S–H(I) in the CaO/Ca(OH)₂–TSD–H₂O systems and a sequence of intermediary
compound formation has been examined. Two series of samples, each being made with different forms of CaO and SiO₂, were
used in the experimental tests. The molar ratio of primary mixtures was CaO/SiO₂ = 1.0. Hydrothermal synthesis has been
carried out under the saturated steam pressure at temperatures of 90, 110, 130, 150 and 175°C; the duration of isothermal
curing was 2, 8, 24 or 72 hours. It was determined that thermal silica densified has negative influence on the formation of
calcium silicate hydrates. Ca²⁺ containing components (Ca(OH)2, CaO) change the composition of intermediate and final
products of the synthesis. In the mixtures with Ca(OH)₂, intermediary and final compound is C–S–H(I) in different crystalline
degree. Meanwhile, in the mixtures with CaO, the main intermediary compound is C–S–H(I) and the main product is xonotlite.
It was estimated that the increment of temperature significantly influences the stability, morphology and crystalline degree
of C–S–H(I). |
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