Speaker
Description
Ternary mixtures composed of calcium aluminate cement (CAC), Portland cement (OPC) and calcium sulfates (CS) are commonly used as tile adhesives, self-levelling compounds, repair cements or technical mortars. Different setting and hardening times as well as expansion, shrinkage and early strength can be easily controlled by varying the proportions of the three components. Many studies have shown that formation of different hydrate phases in the mixtures is strongly influenced by both the OPC/CAC and the CAC/CS ratio. In general, calcium aluminates (C3A and/or CA) can react with the calcium sulfate, which is leading to formation of ettringite. However, the quality of the CACs, which is related to the reactive clinker composition, also has an effect on the composition of the phase formed during and after hydration in the mixture. Depending on the CAC and C$ content or limestone addition (Cc), the conversion of ettringite to AFm (monosulfate or -carbonate) can also be accelerated or prevented.
The influence of two different CACs (iron-containing and iron-free) on the hydration of application-related ternary mixtures was therefore investigated. The reaction kinetics were determined using heat flow calorimetry and quantitative x-ray diffraction analysis (QXRD). Storage samples for up to 90 days at 10 °C and 23 °C were examined with G-factor method in order to clarify the influence of the CA and iron content of the respective clinker on the stable hydrate phase composition and on the amorphous phase content. It could be shown what differences in the phase composition occur during storage at 10 °C or 23 °C. In addition, strength measurements could provide further insights into the influence of the various CACs on the development of strength during hydration.
Affiliations
1 Friedrich-Alexander-Universität Erlangen-Nürnberg, Geozentrum Nordbayern, Lehrstuhl für Mineralogie, Schlossgarten 5a, Erlangen, 91052, Germany
pauline.rost@fau.de
2 Sabanci Technology Center GmbH, Freisinger Landstraße 50, Garching bei München, 85748, Germany
| Title | Development of temperature-dependent phase composition during hydration of ternary OPC-CAC-C$ mixtures with two different CAC types |
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| Keywords | Calcium aluminate cement, Portland cement, Calcium sulfates, Hydration, X-ray diffraction |