A tribute to "Hydrated Calcium Silicates. Part I. Compound Formation at Ordinary Temperatures"


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Title: A tribute to "Hydrated Calcium Silicates. Part I. Compound Formation at Ordinary Temperatures"

Author(s): H.F.W. Taylor

Publication: Special Publication

Volume: 249


Appears on pages(s): 67-80


Date: 3/1/2008


Due to copyright issues, this paper is only available by purchasing the SP-249.

Hydrous calcium silicates prepared at room temperature appear amorphous, but X-ray photographs show that compounds are formed having a considerable degree of crystalline character. Essentially the same product, calcium silicate hydrate (I), can be obtained by the action of water on tricalcium silicate, by double decomposition of calcium nitrate and sodium silicate, or by reaction of calcium hydroxide solution with silica gel, although crystallisation is more mared in the first cae. The composition of this phase varies between approximately CaO,SiO2,aq. and 3CaO,2SiO2,aq. Without significant change in X-ray pattern. The phase relationships between solid and solution have been investigated and are sufficiently reproducible to suggest that the results represent a fair approximation to equilibrium conditions. A second phase, calcium silicate hydrate (II), with a composition in the neighbrourhood of 2CaO,SiO3,aq. And an X-ray pattern differeing only slightly from the above, has been obtained by decomposition of tricalcium silicate and probably exists in equilibrium with calcium hydroxide solutions containing over 1-13 g./l. of CaO. A tentative interpretation fo the X-ray data of calcium silicate hydrate (I) suggests a layer structure, possibly showing some similaritites to the clay minerals.