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Free‐Energy‐Based Model of Chemical Equilibria in the CaO–SiO 2 ‐H 2 O System
Author(s) -
Thomas Jeffrey J.,
Jennings Hamlin M.
Publication year - 1998
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1998.tb02380.x
Subject(s) - tobermorite , solubility , cementitious , energy minimization , phase (matter) , tetrahedron , aqueous solution , materials science , mineralogy , chemical engineering , thermodynamics , chemistry , crystallography , organic chemistry , composite material , cement , computational chemistry , physics , engineering
The chemical equilibrium between the C‐S‐H gel phase and the aqueous phase in the CaO‐SiO 2 ‐H 2 O system was modeled using the free‐energy‐based Thermo‐Calc commercial software system. Unlike programs that are based on solubility products, the minimization of free energy allows the composition and solubility of the C‐S‐H phase to vary, as in real cementitious systems. The C‐S‐H gel is modeled as a defect tobermorite structure, based on recent compositional data gathered using 29 Si NMR. The composition is varied by removal of some of the bridging silica tetrahedra in the SiO layers and by incorporating different amounts of Ca in the interlayer spaces.