Relating Ettringite Formation and Rheological Changes during the Initial Cement Hydration: A Comparative Study Applying XRD Analysis, Rheological Measurements and Modeling
by
Cordula Jakob 1,*, Daniel Jansen 1,*, Neven Ukrainczyk 2, Eddie Koenders 2, Ursula Pott 3, Dietmar Stephan 3
and Jürgen Neubauer 1
Cordula Jakob 1,*, Daniel Jansen 1,*, Neven Ukrainczyk 2, Eddie Koenders 2, Ursula Pott 3, Dietmar Stephan 3 and Jürgen Neubauer 1
1
GeoZentrum Nordbayern, Department of Geography and Geosciences, FAU Erlangen-Nuernberg, 91054 Erlangen, Germany
2
Institute of Construction and Building Materials, TU Darmstadt, 64287 Darmstadt, Germany
3
Building Materials and Construction Chemistry, TU Berlin, 10623 Berlin, Germany
*
Authors to whom correspondence should be addressed.
Materials 2019, 12(18), 2957; https://doi.org/10.3390/ma12182957
Received: 20 August 2019 / Revised: 9 September 2019 / Accepted: 10 September 2019 / Published: 12 September 2019
(This article belongs to the Special Issue Modeling of Cementitious Materials and Structures)
In order to gain a deeper understanding of the rheological development of hydrating ordinary Portland cement (OPC) pastes at initial state, and to better understand their underlying processes, quantitative X-ray diffraction (XRD) analysis and rheological measurements were conducted and their results combined. The time-dependent relation between phase development and flow behavior of cement paste was investigated at two different temperatures (20 and 30 °C), over a period of two hours. Regarding the phase development during hydration, ettringite precipitation was identified as the dominant reaction in the first two hours. For both temperatures, the increasing ettringite content turned out to correlate very well with the loss of workability of the reacting cement paste. An exponential relationship between ettringite growth and flow behavior was observed that could be explained by applying the Krieger-Dougherty equation, which describes the influence of solid fraction on the viscosity of a suspension.
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Keywords:
hydration kinetics; rheology; ettringite formation; OPC; temperature; modeling; scanning electron microscopy (SEM)
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MDPI and ACS Style
Jakob, C.; Jansen, D.; Ukrainczyk, N.; Koenders, E.; Pott, U.; Stephan, D.; Neubauer, J. Relating Ettringite Formation and Rheological Changes during the Initial Cement Hydration: A Comparative Study Applying XRD Analysis, Rheological Measurements and Modeling. Materials 2019, 12, 2957.
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