Influence of Citric Acid on Reactions in the System 3CaO·Al2O3-CaSO4·2H2O-CaO-H2O |
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| Authors: | J TINNEA J F YOUNG |
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| Affiliation: | Departments of Civil Engineering and Ceramic Engineering, University of Illinois, Urbana, Illinois 61801 |
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| Abstract: | The influence of citric acid on paste hydration of 3CaO· Al2O3 in the presence of CaSO4·2H2O and Ca(OH)2 was studied using X-ray diffraction, scanning electron microscopy, and conduction calorimetry. The time at which the citric acid is added (either prior to or with the mixing water) determines how it affects the reactivity of the aluminate. Immediately after the paste is gaged citric acid promotes a more rapid reaction, but later reactions are retarded. Hexagonal calcium aluminate hydrates, ettringite, and monosulfate were all detected as early hydration products. The influence of citric acid on the hydration of 3CaO·Al2O3 slabs immersed in saturated CaSO4·2H2O solutions was also studied and a reaction scheme proposed. |
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