QUANTIFICATION OF BOUND CO2 IN VARIOUS CARBONATED CEMENTITIOUS MATRICES

Author(s): M. Saillio, V. Baroghel-Bouny, M. Bertin, J. Vincent, J.B. de Lacaillerie
Paper category: Proceedings
Book title: CO2STO2019 - International Workshop CO2 Storage in Concrete
Editor(s): Assia Djerbi, Othman Omikrine-Metalssi, Teddy Fen-Chong
ISBN:
e-ISBN: 978-2-35158-232-9
Publisher: RILEM Publications SARL
Publication year: 2019
Pages: 243-253
Total Pages: 11
Language : English

Abstract: For economic and ecological reasons, supplementary cementitious materials (SCM) are
increasingly used in concrete. Although having a lot of advantages, these concretes have
different cement matrices and do not have the same evolution as they are carbonated.
In this paper, comparison between various carbonated cement pastes with/without SCM (slag,
fly ash and metakaolin), has been investigated. Samples are carbonated in accelerated
conditions (1.5 % CO2 , RH 65% and T=20°C) until constant mass but in order to be relatively
close to the natural conditions and to simulate a carbonation process in the long term. The
microstructure was characterized not only by usual techniques such as XRD and TGA-DTA,
but also by 29Si and 27Al NMR spectroscopy. The use of a combination of techniques for
microstructural characterization allows to quantify the proportion of each cementitious phase
and to determine how much there are carbonated in comparison to reference cement pastes.
This quantification shows the evolution of the carbonated cementitious matrix as a function of
the binder content. In addition, the results show that the quantity of bound CO2 is not just
dependent of portlandite amount. All phases with calcium participate to the fixation of CO2.
However, all these phases are not completely carbonated. Bound CO2 is almost only CaCO3.
Four CaCO3 polymorphs are detected : calcite, vaterite, aragonite and amorphous.

Online publication : 2019
Publication type : full_text
Public price (Euros) : 0.00