Gardner, LJ, Walling, SA, Corkhill, CL et al. (5 more authors) (2021) Temperature transformation of blended magnesium potassium phosphate cement binders. Cement and Concrete Research, 141. 106332. p. 106332. ISSN 0008-8846
Abstract
In this study, a multi-technique approach was utilised to determine the high temperature performance of magnesium potassium phosphate cement (MKPC) blended with fly ash (FA) or ground granulated blast furnace slag (GBFS) with respect to nuclear waste immobilisation applications. Conceptual fire conditions were employed (up to 1200 °C, 30 min) to simulate scenarios that could occur during interim storage, transportation or within a final geological disposal facility. After exposure up to 400 °C, the main crystalline phase, struvite-K (MgKPO4·6H2O), was dehydrated to poorly crystalline MgKPO4 (with corresponding volumetric and mass changes), with MgKPO4 recrystallisation achieved by 800 °C. XRD and SEM/EDX analysis revealed reaction occurred between the MgKPO4 and FA/GBFS components after exposure to 1000–1200 °C, with the formation of potassium aluminosilicate phases, leucite and kalsilite (KAlSi2O6 and KAlSiO4), commensurate with a reduced relative intensity (or complete elimination) of the dehydrated struvite-K phase, MgKPO4. This was further supported by solid-state NMR (27Al and 29Si MAS), where only residual features associated with the raw FA/GBFS components were observable at 1200 °C. The high temperature phase transformation of blended MKPC binders resulted in the development of a glass/ceramic matrix with all existing porosity infilled via sintering and the formation of a vitreous phase, whilst the physical integrity was retained (no cracking or spalling). This study demonstrates that, based on small-scaled specimens, blended MKPC binders should perform satisfactorily under fire performance parameters relevant to the operation of a geological disposal facility, up to at least 1200 °C.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/) |
Keywords: | Chemically bonded ceramics; Characterisation; Thermal treatment; Radioactive waste |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Civil Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 13 Jan 2021 10:00 |
Last Modified: | 13 Jan 2021 10:00 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.cemconres.2020.106332 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:169699 |