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Chemical and Microstructural Properties of Designed Cohesive M-S-H Pastes

Concretes can be exposed to a magnesium attack in several environments leading to the formation of magnesium silicate hydrates (M-S-H) and brucite (MH). The formation of M-S-H is likely to alter the properties of the cement matrix because it is linked to the decalcification of C-S-H. However, relati...

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Autores principales: Dewitte, Charlotte, Bertron, Alexandra, Neji, Mejdi, Lacarrière, Laurie, Dauzères, Alexandre
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8782006/
https://www.ncbi.nlm.nih.gov/pubmed/35057269
http://dx.doi.org/10.3390/ma15020547
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author Dewitte, Charlotte
Bertron, Alexandra
Neji, Mejdi
Lacarrière, Laurie
Dauzères, Alexandre
author_facet Dewitte, Charlotte
Bertron, Alexandra
Neji, Mejdi
Lacarrière, Laurie
Dauzères, Alexandre
author_sort Dewitte, Charlotte
collection PubMed
description Concretes can be exposed to a magnesium attack in several environments leading to the formation of magnesium silicate hydrates (M-S-H) and brucite (MH). The formation of M-S-H is likely to alter the properties of the cement matrix because it is linked to the decalcification of C-S-H. However, relatively few data on M-S-H exist in the literature. In order to characterize, physically and mechanically, the M-S-H phase, pure M-S-H cohesive pastes are needed. This work studies the formation of cohesive M-S-H pastes made with MgO-to-SiO(2) atomic ratios of 0.78, 1 and 1.3, from two types of silica (silica fume or colloidal silica) and under 20 °C and 50 °C thermal curing. X-ray diffraction and thermogravimetric analyses confirmed that the consumption of brucite and the formation of M-S-H were quicker with a 50 °C curing. Energy-dispersive X-ray spectroscopy and microtomography showed that colloidal silica enabled a better distribution of the particles than silica fume. Microstructural characterizations were conducted under the protocol with colloidal silica and 50 °C thermal curing. Porosity investigations allowed to describe the M-S-H pastes as highly porous materials with a low content of micropores in comparison with mesopores. The type of mixing influenced the mesopore size distribution.
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spelling pubmed-87820062022-01-22 Chemical and Microstructural Properties of Designed Cohesive M-S-H Pastes Dewitte, Charlotte Bertron, Alexandra Neji, Mejdi Lacarrière, Laurie Dauzères, Alexandre Materials (Basel) Article Concretes can be exposed to a magnesium attack in several environments leading to the formation of magnesium silicate hydrates (M-S-H) and brucite (MH). The formation of M-S-H is likely to alter the properties of the cement matrix because it is linked to the decalcification of C-S-H. However, relatively few data on M-S-H exist in the literature. In order to characterize, physically and mechanically, the M-S-H phase, pure M-S-H cohesive pastes are needed. This work studies the formation of cohesive M-S-H pastes made with MgO-to-SiO(2) atomic ratios of 0.78, 1 and 1.3, from two types of silica (silica fume or colloidal silica) and under 20 °C and 50 °C thermal curing. X-ray diffraction and thermogravimetric analyses confirmed that the consumption of brucite and the formation of M-S-H were quicker with a 50 °C curing. Energy-dispersive X-ray spectroscopy and microtomography showed that colloidal silica enabled a better distribution of the particles than silica fume. Microstructural characterizations were conducted under the protocol with colloidal silica and 50 °C thermal curing. Porosity investigations allowed to describe the M-S-H pastes as highly porous materials with a low content of micropores in comparison with mesopores. The type of mixing influenced the mesopore size distribution. MDPI 2022-01-12 /pmc/articles/PMC8782006/ /pubmed/35057269 http://dx.doi.org/10.3390/ma15020547 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/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 (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Dewitte, Charlotte
Bertron, Alexandra
Neji, Mejdi
Lacarrière, Laurie
Dauzères, Alexandre
Chemical and Microstructural Properties of Designed Cohesive M-S-H Pastes
title Chemical and Microstructural Properties of Designed Cohesive M-S-H Pastes
title_full Chemical and Microstructural Properties of Designed Cohesive M-S-H Pastes
title_fullStr Chemical and Microstructural Properties of Designed Cohesive M-S-H Pastes
title_full_unstemmed Chemical and Microstructural Properties of Designed Cohesive M-S-H Pastes
title_short Chemical and Microstructural Properties of Designed Cohesive M-S-H Pastes
title_sort chemical and microstructural properties of designed cohesive m-s-h pastes
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8782006/
https://www.ncbi.nlm.nih.gov/pubmed/35057269
http://dx.doi.org/10.3390/ma15020547
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