The System Na2O-CaO-SiO2-H2O |
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| Authors: | Paul Wencil Brown |
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| Affiliation: | Department of Materials Science, The Pennsylvania State University, University Park, Pennsylvania 16801 |
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| Abstract: | A portion of the quaternary phase diagram for Na2O-CaO-SiO2-H2O has been constructed. Plotting concentrations as their 10th roots allows compounds having solubilities which differ by several orders of magnitude to be represented on a single diagram. The compositional relationships among sodium-substituted calcium silicate hydrate, calcium-substituted sodium silicate hydrate, calcium bydroxide, a quaternary compound of approximate composition 0.25Na2O · CaO · SiO2· 3H2O, sodium hydroxide monohydrate, and miscellaneous sodium silicate hydrates are presented. The quaternary diagram constructed shows the quaternary compound to exist in equilibrium with sodium-substituted calcium silicate hydrate and calcium hydroxide. Conditions in concrete pore solutions which favor the formation of this quaternary compound may also favor the occurrence of the alkali-silica reaction. |
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| Keywords: | equilibrium diagrams soda-lime-silica hydrates phase equilibria |
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