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

Gregor J.G. Gluth, Xinyuan Ke, Anya Vollpracht, Lia Weiler, Susan A. Bernal, Martin Cyr, Katja Dombrowski-Daube, Dan Geddes, Cyrill Grengg, Cassandre Le Galliard, Marija Nedeljkovic, John L. Provis, Luca Valentini, Brant Walkley

Research output: Chapter or section in a book/report/conference proceedingChapter or section

Abstract

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 + MgOeq + Na2Oeq + K2Oeq) 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.

Original languageEnglish
Title of host publicationInternational RILEM Conference on Synergising Expertise towards Sustainability and Robustness of Cement-based Materials and Concrete Structures. SynerCrete 2023
EditorsA. Jędrzejewska, F. Kanavaris, M. Azenha, F. Benboudjema, D. Schlicke
Place of PublicationCham, Switzerland
PublisherSpringer Science and Business Media B.V.
Pages1029-1037
Number of pages9
ISBN (Electronic)9783031331879
ISBN (Print)9783031331862
DOIs
Publication statusPublished - 2023

Publication series

NameRILEM Bookseries
Volume44
ISSN (Print)2211-0844
ISSN (Electronic)2211-0852

Bibliographical note

Funding Information:
Acknowledgements. Discussions with the members of RILEM TC 281-CCC are gratefully acknowledged. Participation of S. A. Bernal in this study was sponsored by the Engineering and Physical Sciences Research Council (EPSRC) through the Early Career Fellowship EP/R001642/1, and the National Science Foundation/ EPSRC lead agency RENACEM grant EP/T008407/1 and 1903457. Participation of J. L. Provis in this study was supported by the Engineering and Physical Sciences Research Council through grant EP/T008407/1.

Keywords

  • Accelerated testing
  • Alkali-activated materials
  • Carbonation
  • Durability
  • Pore structure

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Mechanics of Materials

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