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In situ synchrotron powder diffraction study of the setting reaction kinetics of magnesium-potassium phosphate cements
Abstract This work reports a kinetic study of the formation of magnesium-potassium phosphate cements accomplished using in-situ synchrotron powder diffraction. The reaction: MgO+KH2PO4 +5H2O→MgKPO4 ·6H2O was followed in situ in the attempt of contributing to explain the overall mechanism and assess the influence of periclase (MgO) grain size and calcination temperature (1400-1600°C) on the reaction kinetics. Numerical kinetic parameters for the setting reaction have been provided for the first time. The best fit to the kinetic data was obtained using a weighted nonlinear model fitting method with two kinetic equations, representing two consecutive, partially overlapping processes. MgO decomposition could be described by a first order (F1) model followed by a Jander diffusion (D3) controlled model. Crystallization of the product of reaction was modelled using an Avrami model (An) followed by a first order (F1) chemical reaction. A reaction mechanism accounting for such results has been proposed.
In situ synchrotron powder diffraction study of the setting reaction kinetics of magnesium-potassium phosphate cements
Abstract This work reports a kinetic study of the formation of magnesium-potassium phosphate cements accomplished using in-situ synchrotron powder diffraction. The reaction: MgO+KH2PO4 +5H2O→MgKPO4 ·6H2O was followed in situ in the attempt of contributing to explain the overall mechanism and assess the influence of periclase (MgO) grain size and calcination temperature (1400-1600°C) on the reaction kinetics. Numerical kinetic parameters for the setting reaction have been provided for the first time. The best fit to the kinetic data was obtained using a weighted nonlinear model fitting method with two kinetic equations, representing two consecutive, partially overlapping processes. MgO decomposition could be described by a first order (F1) model followed by a Jander diffusion (D3) controlled model. Crystallization of the product of reaction was modelled using an Avrami model (An) followed by a first order (F1) chemical reaction. A reaction mechanism accounting for such results has been proposed.
In situ synchrotron powder diffraction study of the setting reaction kinetics of magnesium-potassium phosphate cements
Viani, Alberto (Autor:in) / Peréz-Estébanez, Marta (Autor:in) / Pollastri, Simone (Autor:in) / Gualtieri, Alessandro Francesco (Autor:in)
Cement and Concrete Research ; 79 ; 344-352
16.10.2015
9 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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