Bernal, S.A., van Deventer, J.S.J. and Provis, J.L. (2015) What happens to 5 year old metakaolin geopolymers’ the effect of alkali cation. In: Calcined Clays for Sustainable Concrete. 1st International Conference on Calcined Clays for Sustainable Concrete, June 23rd -25th 2015, Lausanne, CH. RILEM Bookseries, 10 . Springer Verlag , pp. 315-321.
Abstract
In this study we report X-ray diffraction and dilatometry results of metakaolin (MK) geopolymers produced with Na, K, Rb or Cs silicate solutions, and cured for 7 days and 5 years, with the aim of identifying variations in structure and performance (dimensional stability at elevated temperature) over an extended curing period at ambient temperature. All of the geopolymers studied are mainly X-ray amorphous after 5 years of curing; however, in Rb-based and Cs-based geopolymers formation of aluminosilicate crystalline phases was identified. As the alkali cation radius increases, so does the thermal stability of the MK-geopolymer, potentially as a consequence of the combined effect of the higher degree of ordering of the geopolymer itself, which might retard the dehydration of the geopolymers upon heating, and the reduced energy of hydration of larger alkali cations. The 7-day and 5-year cured samples produced with Rb and Cs silicate solutions do not exhibit significant dimensional changes above 300 °C, with a maximum shrinkage of <2% after exposure to 1100 °C. This shows that increasing the radius of the alkali cation during geopolymerisation of MK has an effect on the thermal stability of these materials, and promotes the formation of a highly densified and rigid structure at advanced curing ages.
Metadata
Item Type: | Proceedings Paper |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © RILEM 2015. This is an author produced version of a paper subsequently published in Calcined Clays for Sustainable Concrete. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Civil and Structural Engineering (Sheffield) The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 23 Feb 2016 17:09 |
Last Modified: | 12 May 2016 21:27 |
Published Version: | http://dx.doi.org/10.1007/978-94-017-9939-3_39 |
Status: | Published |
Publisher: | Springer Verlag |
Series Name: | RILEM Bookseries |
Refereed: | Yes |
Identification Number: | 10.1007/978-94-017-9939-3_39 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:94584 |