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Reactivity of Gypsum-Based Materials Subjected to Thermal Load: Investigation of Reaction Mechanisms

The thermal stability of gypsum-based materials, and in this context, especially their long-term behavior, is the background of our current research activities. A comprehensive investigation program was compiled in which detailed examinations of various model materials exposed to thermal loads were...

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Autores principales: Krause, Felix, Renner, Bernhard, Coppens, Frederik, Dewanckele, Jan, Schwotzer, Matthias
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142976/
https://www.ncbi.nlm.nih.gov/pubmed/32245074
http://dx.doi.org/10.3390/ma13061427
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author Krause, Felix
Renner, Bernhard
Coppens, Frederik
Dewanckele, Jan
Schwotzer, Matthias
author_facet Krause, Felix
Renner, Bernhard
Coppens, Frederik
Dewanckele, Jan
Schwotzer, Matthias
author_sort Krause, Felix
collection PubMed
description The thermal stability of gypsum-based materials, and in this context, especially their long-term behavior, is the background of our current research activities. A comprehensive investigation program was compiled in which detailed examinations of various model materials exposed to thermal loads were carried out. The understanding of the partly not entirely consistent state of knowledge shall be sharpened especially by in situ observations of the thermally induced conversion reaction of gypsum into hemihydrate. The temporal course of the reaction was investigated non-destructively by in situ investigations in a high-resolution X-ray computed tomography setup, and the experiment was accompanied by detailed characterizations of the microstructure and composition. In this contribution, selected results of experiments with a high-purity natural gypsum rock as the model substance are presented. Studying the influence of temperature on the reaction showed that, even under supposedly dry conditions, the reaction could take place at much lower temperatures than usually reported in the literature. It was demonstrated that the transformation of gypsum into hemihydrate could take place at a temperature of already 50 °C. The results indicated that even under “classical” heating conditions in a conventional oven, the dissolution and crystallization processes in water films on the mineral surfaces could be suggested to be a driving force for the reaction. A corresponding reaction model, which took these aspects into account, was proposed in this work.
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spelling pubmed-71429762020-04-14 Reactivity of Gypsum-Based Materials Subjected to Thermal Load: Investigation of Reaction Mechanisms Krause, Felix Renner, Bernhard Coppens, Frederik Dewanckele, Jan Schwotzer, Matthias Materials (Basel) Article The thermal stability of gypsum-based materials, and in this context, especially their long-term behavior, is the background of our current research activities. A comprehensive investigation program was compiled in which detailed examinations of various model materials exposed to thermal loads were carried out. The understanding of the partly not entirely consistent state of knowledge shall be sharpened especially by in situ observations of the thermally induced conversion reaction of gypsum into hemihydrate. The temporal course of the reaction was investigated non-destructively by in situ investigations in a high-resolution X-ray computed tomography setup, and the experiment was accompanied by detailed characterizations of the microstructure and composition. In this contribution, selected results of experiments with a high-purity natural gypsum rock as the model substance are presented. Studying the influence of temperature on the reaction showed that, even under supposedly dry conditions, the reaction could take place at much lower temperatures than usually reported in the literature. It was demonstrated that the transformation of gypsum into hemihydrate could take place at a temperature of already 50 °C. The results indicated that even under “classical” heating conditions in a conventional oven, the dissolution and crystallization processes in water films on the mineral surfaces could be suggested to be a driving force for the reaction. A corresponding reaction model, which took these aspects into account, was proposed in this work. MDPI 2020-03-20 /pmc/articles/PMC7142976/ /pubmed/32245074 http://dx.doi.org/10.3390/ma13061427 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Krause, Felix
Renner, Bernhard
Coppens, Frederik
Dewanckele, Jan
Schwotzer, Matthias
Reactivity of Gypsum-Based Materials Subjected to Thermal Load: Investigation of Reaction Mechanisms
title Reactivity of Gypsum-Based Materials Subjected to Thermal Load: Investigation of Reaction Mechanisms
title_full Reactivity of Gypsum-Based Materials Subjected to Thermal Load: Investigation of Reaction Mechanisms
title_fullStr Reactivity of Gypsum-Based Materials Subjected to Thermal Load: Investigation of Reaction Mechanisms
title_full_unstemmed Reactivity of Gypsum-Based Materials Subjected to Thermal Load: Investigation of Reaction Mechanisms
title_short Reactivity of Gypsum-Based Materials Subjected to Thermal Load: Investigation of Reaction Mechanisms
title_sort reactivity of gypsum-based materials subjected to thermal load: investigation of reaction mechanisms
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142976/
https://www.ncbi.nlm.nih.gov/pubmed/32245074
http://dx.doi.org/10.3390/ma13061427
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