Kinetics of the Early Hydration of Tricalcium Aluminate in Solutions Containing Calcium Sulfate |
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Authors: | PAUL WENCIL BROWN LAWRENCE O LIBERMAN GEOFFREY FROHNSDORFF |
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Affiliation: | National Bureau of Standards, Washington, DC 20234 |
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Abstract: | The rates of reaction of 3CaO. Al2O3, in sulfate-containing solutions of three compositions were investigated. It was observed that the rates of calcium and sulfate uptake decreased with increasing calcium hydroxide concentration. In a further experiment using a calcium sulfate solution, which also contained NaOH, it was established that the kinetics of calcium sulfoaluminate hydrate formation are strongly dependent on the hydroxyl ion concentration. The rate of sulfate ion consumption per unit surface area of 3CaO·Al2O3 was observed to be constant during the period in which a calcium sulfoaluminate hydrate is a reaction product. The ratio of calcium-to-sulfate ions consumed in the hydration reactions investigated exceeded unity suggesting the formation of 4CaO·Al2O3· n H2O in addition to ettringite. |
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