Humad, A.M., Provis, J.L. orcid.org/0000-0003-3372-8922 and Cwirzen, A. (2018) Alkali activation of a high MgO GGBS – fresh and hardened properties. Magazine of Concrete Research, 70 (24). pp. 1256-1264. ISSN 0024-9831
Abstract
In this study, concretes and pastes were produced from a high magnesium oxide (MgO) ground granulated blast furnace slag (magnesium oxide content 16·1 wt%) by alkali activation with various amounts and combinations of sodium carbonate and sodium silicate. Sodium carbonate activators tended to reduce slump compared to sodium silicate at the same dose, and, in contrast to the literature for many blast furnace slags with more moderate magnesium oxide, to shorten the initial and final setting times in comparison with concretes activated by sodium silicate for dosages less than 10 wt%. Higher heat curing temperatures and the use of larger dosages of alkali activators resulted in higher early-age compressive cube strength values. The X-ray diffraction analysis of 7 and 28 d old pastes activated with sodium carbonates revealed formation of gaylussite, calcite, nahcolite and calcium-aluminium-silicate-hydrate (C–A–S–H) gel. Curing at 20°C appeared to promote dissolution of gaylussite and calcite, while heat curing promoted their replacement with C–A–S–H, which also resulted in higher ultimate cube compressive strength values. Conversely, mixes activated with sodium silicate contained less crystalline phases and more disordered gel, which strengthened the binder matrix.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 ICE Publishing. This is an author-produced version of a paper subsequently published in Magazine of Concrete Research. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | compressive strength; curing; setting properties |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 11 Jun 2019 14:10 |
Last Modified: | 14 Nov 2019 02:05 |
Status: | Published |
Publisher: | ICE Publishing |
Refereed: | Yes |
Identification Number: | 10.1680/jmacr.17.00436 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:146693 |