Wang, L., Geddes, D.A., Walkley, B. orcid.org/0000-0003-1069-1362 et al. (3 more authors) (2020) The role of zinc in metakaolin-based geopolymers. Cement and Concrete Research, 136. 106194. ISSN 0008-8846
Abstract
Geopolymers are low-calcium, sustainable cementitious materials. The role of Zn, a known retardant used in Portland cement, in geopolymer systems is not well understood. This study scrutinises the effect of Zn on metakaolin-based geopolymer reaction mechanisms and kinetics, and investigates the incorporation mechanism of Zn in geopolymer gels. Isothermal calorimetry and X-ray diffraction analyses show that substitution of ZnO (20 mol% c.f. metakaolin) significantly hinders reaction, likely due to preferential formation of a Na/K-Zn containing phase. Solid-state nuclear magnetic resonance spectroscopy shows that Zn2+ partially substitutes for Na+/K+ in charge-balancing sites within the geopolymer gel. Setting time and leaching tests show that the retarding effect of Zn on reaction kinetics is significantly greater in Na-activated geopolymers compared with K-activated geopolymers, whereas Na-activated geopolymers exhibit superior fixation capacity to Zn. A lab-scale experiment demonstrates that metakaolin-based geopolymers are promising candidates for the stabilisation/solidification of Zn-rich hazardous waste.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 Elsevier. This is an author produced version of a paper subsequently published in Cement and Concrete Research. Uploaded in accordance with the publisher's self-archiving policy. Article available under the terms of the CC-BY-NC-ND licence (https://creativecommons.org/licenses/by-nc-nd/4.0/). |
Keywords: | Geopolymer; Alkali-activation; Reaction kinetics; Retarding mechanism; Hazardous waste immobilisation; Zn leachability |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Chemical and Biological Engineering (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 13 Aug 2020 09:28 |
Last Modified: | 04 Aug 2021 00:38 |
Status: | Published |
Publisher: | Elsevier BV |
Refereed: | Yes |
Identification Number: | 10.1016/j.cemconres.2020.106194 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:164372 |
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Filename: CEMCON_Supplementary data_final version.pdf
Licence: CC-BY-NC-ND 4.0