Silicate production solid-state reaction

The BaO is produced in the form of very small particles of nearly atomic proportions which react immediately to form the silicate. Actually, the rate of reaction is proportional to the number of nuclei produced per unit vdlume. A nucleus is a point where atoms or ions have reacted and begun the formation of the product structure. In the case of the BaO reaction, the number of nuclei formed per unit of time is small and formation of the structure is diffusion limited. In the case of BaCOa decomposition, the atomic-proportioned BaO reacts nearly as fast as it is formed so that the number of nuclei per unit volume is enormously increased. It is thus apparent that if we wish to increase solid state reaction rates, one way to do so is to use a decomposition reaction to supply the reacting species, we will further address this type of reaction later on in our discussion. 

Calcium Silicates Hydrates (CSH) is the major hydration product of Portland Cement. It has been intensively studied for several decades. CSH can be obtained by hydration of C3S and P-C2S or by precipitation fi om aqueous solutions containing a Ca salt and silicate ions. CSH has a wide range of chemical composition. Many studies [1-5] indicate that its molar ratio Ca/Si can vary fixrm 0.7 to 2 (or more) [6] and is in most cases near to 1.7 [7]. There has been indirect evidence that CSH (obtained by reaction between CaO and Silica) has a layered structure similar to that of natural Tobermorite and/or Jennite [8]. Recent solid state NMR [9-10], intfared spectroscopy [11], EXAFS [12] and thermogravimetry works [14] have... 

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