Carbonation rate of alkali-activated concretes and high-volume SCM concretes

Carbonation rate of alkali-activated concretes and high-volume SCM concretes: a literature data analysis by RILEM TC 281-CCC

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)
Dombrowski-Daube, Katja (University of Technology Bergakademie Freiberg)
Geddes, Daniel A. (University of Sheffield)
Grengg, Cyrill (Graz University of Technology)
Nedeljković, Marija (TU Delft Materials and Environment)

2022

The current understanding of the carbonation and the prediction of the carbonation rate of alkali-activated concretes is complicated inter alia by the wide range of binder chemistries used and testing conditions adopted. To overcome some of the limitations of individual studies and to identify general correlations between mix design parameters and carbonation resistance, the RILEM TC 281-CCC ‘Carbonation of Concrete with Supplementary Cementitious Materials’ 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 analysis indicates that water/CaO ratio and water/binder ratio exert an influence on the carbonation resistance of alkali-activated concretes; however, these parameters are not good indicators of the carbonation resistance when considered individually. A better indicator of the carbonation resistance of alkali-activated concretes under conditions approximating natural carbonation appears to be their water/(CaO + MgO_eq + Na₂O_eq + K₂O_eq) ratio, where the subscript ‘eq’ indicates an equivalent amount based on molar masses. Nevertheless, this ratio can serve as approximate indicator at best, as other parameters also affect the carbonation resistance of alkali-activated concretes. In addition, the analysis of the database points to peculiarities of accelerated tests using elevated CO₂ concentrations for low-Ca alkali-activated concretes, indicating that even at the relatively modest concentration of 1% CO₂, accelerated testing may lead to inaccurate predictions of the carbonation resistance under natural exposure conditions.

Accelerated testing
Alkali-activated materials
Carbonation
Durability

http://resolver.tudelft.nl/uuid:db94602c-dce2-406f-a16e-18e28d2ac864

https://doi.org/10.1617/s11527-022-02041-4

1359-5997

Materials and Structures, 55 (8)

Institutional Repository

journal article

© 2022 Gregor J.G. Gluth, Xinyuan Ke, Anya Vollpracht, Lia Weiler, Susan A. Bernal, Katja Dombrowski-Daube, Daniel A. Geddes, Cyrill Grengg, Marija Nedeljković, More Authors