Effect of supplementary cementitious materials on carbonation of cement pastes

Supplementary cementitious materials (SCM) are increasingly used in concrete for economical and environmental reasons. However, the durability of reinforced concretes against, for example, corrosion induced by carbonation varies. Here, the phase assemblage of various cement pastes with/without SCM (...

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Bibliographic Details
Published in:Cement and concrete research 2021-04, Vol.142, p.106358, Article 106358
Main Authors: Saillio, Mickael, Baroghel-Bouny, Véronique, Pradelle, Sylvain, Bertin, Matthieu, Vincent, Julien, d'Espinose de Lacaillerie, Jean-Baptiste
Format: Article
Language:English
Subjects:
Aluminosilicates
Aluminum silicates
Carbonation
Cement paste
Engineering Sciences
Fly ash
Hydrates
MAS NMR spectroscopy
Materials
Metakaolin
NMR spectroscopy
Phases
SCM
Slag
TGA/DTG
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Summary:Supplementary cementitious materials (SCM) are increasingly used in concrete for economical and environmental reasons. However, the durability of reinforced concretes against, for example, corrosion induced by carbonation varies. Here, the phase assemblage of various cement pastes with/without SCM (slag, fly ash and metakaolin), carbonated in accelerated conditions (1.5% CO2 and 65% RH) or not, has been investigated by various technics (XRD, TGA/DTA and 29Si as well as 27Al nuclear magnetic resonance spectroscopy) and compared. Results show that, after carbonation, anhydrous phases are less decalcified than hydrated phases. In cement pastes with slag, most of the calcium remains in the non-hydrated part of the slag. In contrast, the C-A,S-H phase is deeply modified and results show a coupling between C-A,S-H and hydrated aluminate phases during carbonation. In all carbonated materials, these phases tend to become an aluminosilicate gel, a very amorphous/disordered phase, containing less water than the original hydrates.
ISSN:0008-8846
1873-3948
DOI:10.1016/j.cemconres.2021.106358