A Kinetic Study of the Pozzolanic Reaction of Fly Ash, CaO, and Na<sub>2</sub>O in the Preparation of Fly Ash Belite Cement

Fly ash belite cement is a kind of low-carbon cement prepared by a two-step process involving hydrothermal synthesis and low-temperature calcination. Pozzolanic reaction pastes, as the precursors of fly ash belite cement prepared by hydrothermal synthesis, are affected mainly by reaction temperature...

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Main Authors:	Yongfan Gong, Ben Yu, Yonghao Fang, Dingyi Yang, Shu-an Wu, Yurong Yan
Format:	Article
Language:	English
Published:	MDPI AG 2019-10-01
Series:	Materials
Subjects:	low activity fly ash belite cement hydrothermal reaction naoh kinetic model
Online Access:	https://www.mdpi.com/1996-1944/12/20/3303

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spelling	doaj-310ee5a6075c47278324df008db0e7f42020-11-25T01:32:07ZengMDPI AGMaterials1996-19442019-10-011220330310.3390/ma12203303ma12203303A Kinetic Study of the Pozzolanic Reaction of Fly Ash, CaO, and Na<sub>2</sub>O in the Preparation of Fly Ash Belite CementYongfan Gong0Ben Yu1Yonghao Fang2Dingyi Yang3Shu-an Wu4Yurong Yan5Departments of Civil Science and Engineering, University of Yangzhou, Yangzhou 225127, ChinaDepartments of Civil Science and Engineering, University of Yangzhou, Yangzhou 225127, ChinaCollege of Mechanics and Materials, University of Hohai, Nanjing 210098, ChinaDepartments of Civil Science and Engineering, University of Yangzhou, Yangzhou 225127, ChinaDepartments of Building Engineering, University of Yangzhou Polytechnic, Yangzhou 225009, ChinaDepartments of Building Engineering, University of Yangzhou Polytechnic, Yangzhou 225009, ChinaFly ash belite cement is a kind of low-carbon cement prepared by a two-step process involving hydrothermal synthesis and low-temperature calcination. Pozzolanic reaction pastes, as the precursors of fly ash belite cement prepared by hydrothermal synthesis, are affected mainly by reaction temperature, time, ratios of the mass of fly ash/lime (FA/CA), and the dosage of Na<sub>2</sub>O. The absorbance rate of CaO with reaction time was tested for all samples, and the reaction kinetic model and parameters of the granule-hydrothermal synthesis method were discussed. A kinetic model for the hydrothermal synthesis in the presence of Na<sub>2</sub>O was proposed based on the Kondo’s modified Jander equation and Arrhenius equation. The activation energy (Ea) of the process was determined to be 67.76 kJ/mol. In addition, with an increasing dosage of Na<sub>2</sub>O, the pre-exponential factor A of the Arrhenius equation increased. However, the hydrothermal reaction degree was accurately predicted using the kinetic model characterized by the absorption rate of CaO. The results indicated that Na<sub>2</sub>O, as an alkali activator, facilitated the diffusion of Ca<sup>2+</sup> firstly, then partly dissolved the amorphous phase in the mixtures and, finally, accelerated the formation of poorly crystallized hydrates.https://www.mdpi.com/1996-1944/12/20/3303low activityfly ashbelite cementhydrothermal reactionnaohkinetic model
collection	DOAJ
language	English
format	Article
sources	DOAJ
author	Yongfan Gong Ben Yu Yonghao Fang Dingyi Yang Shu-an Wu Yurong Yan
spellingShingle	Yongfan Gong Ben Yu Yonghao Fang Dingyi Yang Shu-an Wu Yurong Yan A Kinetic Study of the Pozzolanic Reaction of Fly Ash, CaO, and Na<sub>2</sub>O in the Preparation of Fly Ash Belite Cement Materials low activity fly ash belite cement hydrothermal reaction naoh kinetic model
author_facet	Yongfan Gong Ben Yu Yonghao Fang Dingyi Yang Shu-an Wu Yurong Yan
author_sort	Yongfan Gong
title	A Kinetic Study of the Pozzolanic Reaction of Fly Ash, CaO, and Na<sub>2</sub>O in the Preparation of Fly Ash Belite Cement
title_short	A Kinetic Study of the Pozzolanic Reaction of Fly Ash, CaO, and Na<sub>2</sub>O in the Preparation of Fly Ash Belite Cement
title_full	A Kinetic Study of the Pozzolanic Reaction of Fly Ash, CaO, and Na<sub>2</sub>O in the Preparation of Fly Ash Belite Cement
title_fullStr	A Kinetic Study of the Pozzolanic Reaction of Fly Ash, CaO, and Na<sub>2</sub>O in the Preparation of Fly Ash Belite Cement
title_full_unstemmed	A Kinetic Study of the Pozzolanic Reaction of Fly Ash, CaO, and Na<sub>2</sub>O in the Preparation of Fly Ash Belite Cement
title_sort	kinetic study of the pozzolanic reaction of fly ash, cao, and na<sub>2</sub>o in the preparation of fly ash belite cement
publisher	MDPI AG
series	Materials
issn	1996-1944
publishDate	2019-10-01
description	Fly ash belite cement is a kind of low-carbon cement prepared by a two-step process involving hydrothermal synthesis and low-temperature calcination. Pozzolanic reaction pastes, as the precursors of fly ash belite cement prepared by hydrothermal synthesis, are affected mainly by reaction temperature, time, ratios of the mass of fly ash/lime (FA/CA), and the dosage of Na<sub>2</sub>O. The absorbance rate of CaO with reaction time was tested for all samples, and the reaction kinetic model and parameters of the granule-hydrothermal synthesis method were discussed. A kinetic model for the hydrothermal synthesis in the presence of Na<sub>2</sub>O was proposed based on the Kondo’s modified Jander equation and Arrhenius equation. The activation energy (Ea) of the process was determined to be 67.76 kJ/mol. In addition, with an increasing dosage of Na<sub>2</sub>O, the pre-exponential factor A of the Arrhenius equation increased. However, the hydrothermal reaction degree was accurately predicted using the kinetic model characterized by the absorption rate of CaO. The results indicated that Na<sub>2</sub>O, as an alkali activator, facilitated the diffusion of Ca<sup>2+</sup> firstly, then partly dissolved the amorphous phase in the mixtures and, finally, accelerated the formation of poorly crystallized hydrates.
topic	low activity fly ash belite cement hydrothermal reaction naoh kinetic model
url	https://www.mdpi.com/1996-1944/12/20/3303
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A Kinetic Study of the Pozzolanic Reaction of Fly Ash, CaO, and Na<sub>2</sub>O in the Preparation of Fly Ash Belite Cement

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