Carbonation Rate of Alkali-Activated Concretes

Carbonation Rate of Alkali-Activated Concretes: Effects of Compositional Parameters and Carbonation Conditions

Gluth, Gregor J.G. (Federal Institute for Materials Research and Testing Berlin)
Ke, Xinyuan (University of Bath)
Vollpracht, Anya (Rheinisch-Westfälische Technische Hochschule)
Weiler, Lia (Rheinisch-Westfälische Technische Hochschule)
Bernal, Susan A. (University of Leeds)
Cyr, Martin (Université de Toulouse)
Dombrowski-Daube, Katja (University of Technology Bergakademie Freiberg)
Geddes, Dan (University of Sheffield)
Nedeljković, Marija (TU Delft Materials and Environment)

2023

The current ability to predict the carbonation resistance of alkali-activated materials (AAMs) is incomplete, partly because of widely varying AAM chemistries and variable testing conditions. To identify general correlations between mix design parameters and the carbonation rate of AAMs, RILEM TC 281-CCC Working Group 6 compiled and analysed carbonation data for alkali-activated concretes and mortars from the literature. For comparison purposes, data for blended Portland cement-based concretes with a high percentage of SCMs (≥66% of the binder) were also included in the database. The results show that the water/CaO ratio is not a reliable indicator of the carbonation rate of AAMs. A better indicator of the carbonation rate of AAMs under conditions approximating natural carbonation is their water/(CaO + MgO_eq + Na₂O_eq + K₂O_eq) ratio, where the index ‘eq’ indicates an equivalent amount based on molar masses. This finding can be explained by the CO₂ binding capacity of alkaline-earth and alkali metal ions; the obtained correlation also indicates an influence of the space-filling capability of the binding phases of AAMs, as for conventional cements. However, this ratio can serve only as an approximate indicator of carbonation resistance, as other parameters also affect the carbonation resistance of alkali-activated concretes. In addition, the analysis of the dataset revealed peculiarities of accelerated tests using elevated CO₂ concentrations for low-Ca AAMs, indicating that even at the relatively modest concentration of 1% CO₂, accelerated testing may lead to inaccurate predictions of their carbonation resistance under natural exposure conditions.

Accelerated testing
Alkali-activated materials
Carbonation
Durability
Pore structure

http://resolver.tudelft.nl/uuid:7e3c43d5-ef70-40f9-90b8-80e64944f4df

https://doi.org/10.1007/978-3-031-33187-9_94

Springer

2023-12-09

978-3-031-33186-2

International RILEM Conference on Synergising Expertise towards Sustainability and Robustness of Cement-based Materials and Concrete Structures: SynerCrete’23 - Volume 2, 44

SynerCrete 2023, 2023-06-14 → 2023-06-15, The Milos Conference Center – George Eliopoulos, Adamantas, Greece

RILEM Bookseries, 2211-0844, 44

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

book chapter

© 2023 Gregor J.G. Gluth, Xinyuan Ke, Anya Vollpracht, Lia Weiler, Susan A. Bernal, Martin Cyr, Katja Dombrowski-Daube, Dan Geddes, Marija Nedeljković, More Authors