NATURAL DEGREE OF CARBONATION OF SPANISH CEMENTS AND GLOBAL CALCULATION OF CO2 UPTAKE

Author(s): C. Andrade
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: 14
Total Pages: 1
Language : English

Abstract: Traditionally in concrete the degree of carbonation is understood as the depth of carbonation.
However for the sake of carbon storage, the degree of carbonation, DoC, is the amount of
carbon dioxide fixed in the carbonated zone with respect to the maximum amount that could
be uptake. It is very seldom measured and only isolated values were found in the literature. A
DoC=100% means that all the CaO of the cement is combined and converted into CaCO3
which correspond to the CO2 emissions (around 520 Kg/t clinker) produced during the clinker
fabrication due to the decarbonation step. This DoC= 100% would be the target for maximum
capture ability of recycled aggregates. However, the full carbonation is not usually obtained
due to the reaction depends on the porous microstructure, the moisture level in it and to the
type of cement. In accelerated carbonation there is the additional risk of producing a “coating”
of CaCO3 on the porous surfaces that prevents further carbonation. In present paper are
presented results of the DoC of a set of concretes fabricated with cements produced in Spain
and exposed during 4 years to natural atmospheres (indoor and outdoor sheltered and non-
sheltered from rain). The results indicated that all cement types, except those containing high
proportions of GGBS, exhibited DoC of around 62.5% with a lower limit of 23% for a fractile of
5%. In the paper is also presented the methodology of calculation in the study at world (global)
level on the amount of CO2 combined due to the carbonation of concrete.

Online publication : 2019
Publication type : full_text
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