Efficiency and influence of calcined phyllosilicates during the early hydration of cement
Final Report Abstract
The building materials industry urgently needs to cover an increasing demand for binders reduced in clinker, by using higher amounts of high-performing cement and concrete additives. The availability of well-established supplementary cementitious materials, especially coal fly ash and blast furnace slag, will decline and not be sufficient within the next years and decades. Hence, it requires solutions towards alternative, ecological and economical attractive materials with global availability. Calcined clays, especially calcined common clays, offer here a great potential and will represent a key resource for the building materials industry. Due to their complex mineralogy, however, they require a fundamental, scientific knowledge when being used as binder component. This research project investigated the mechanisms of four different phyllosilicates as main components in clays, after their calcination (so called meta-phyllosilicates) and their interaction with clinker phases during early hydration. The results revealed a significant discrepancy regarding the mechanism of the meta-phyllosilicates investigated: metakaolin (MK), metaillite (MI), metasmectite (MS) and metamuscovite (MM). The MK leads to a significant, independent contribution to strength development thanks to its early pozzolanic reaction. However, it tremendously slows down the alite reaction. The MM, instead, does not exhibit any pozzolanic reactivity but promotes the alite reaction compared to all reference systems during the investigated period of time. The MI exhibits a pozzolanic reaction within the first 50 hours of hydration, which is roughly at 30 % compared to MK. However, it influences the reactivity of cement clinker phases to a lesser extent compared to MK. The MS has a rather low reactivity during early hydration and an own pozzolanic contribution beyond two days only, whereas the hydration of cement is delayed only marginally, as observed with MI. The research results reveal a good performance of less reactive meta-phyllosilicates in cementitious binders and further confirm the promising suitability of common clays with moderate reactivity. Depending on their composition, calcined clays are hence suitable for a large variety of applications in concrete technology. The output of this research project provides a significant milestone for the use of calcined clays in composite cements or as concrete additive.
Publications
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Methodological investigations on quantifications of in situ X-ray diffraction for a reliable characterization of the reaction kinetics of calcined clays during early hydration. (2021), Universität der Bundeswehr München: Neubiberg, Germany. p. 105.
S. Scherb
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Reaction kinetics during early hydration of calcined phyllosilicates in clinker-free model systems. Cement and Concrete Research, 143, 106382.
Scherb, Sebastian; Maier, Matthias; Beuntner, Nancy; Thienel, Karl-Christian & Neubauer, Jürgen
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Reaction kinetics of calcined phyllosilicates in synthetic cement systems, in International Conference on Calcined Clays for Sustainable Concrete, M. Sharma, H. Hafez, F. Zunino, and K. Scrivener, Editors. (2022): Lausanne, Switzerland. p. 66-67.
S. Scherb; M. Maier; M. Köberl; N. Beuntner & K.-C. Thienel
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Das Potenzial calcinierter Tone – Inwiefern hilft uns die Tonmineralogie, die Eigenschaften als Betonzusatzstoff Typ II zu prognostizieren und zu steuern? Vortrag auf der 21. Internationale Baustofftagung ibausil, 13.-15. September 2023 in Weimar
N. Beuntner; S. Scherb; M. Panzer & K.-C. Thienel
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Reaction Kinetics During Early Hydration of Calcined Phyllosilicates in Model Cement Systems. Elsevier BV.
Scherb, Sebastian; Maier, Matthias; Mathias, Köberl; Beuntner, Nancy & Thienel, Karl-Christian
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Sulfate consumption during the hydration of Alite and its influence by SCMs, Vortrag auf der 21. Internationale Baustofftagung ibausil, 13.-15. September 2023 in Weimar
M. Maier; S. Scherb & K.-C. Thienel
