Najafi Kani, E., Allahverdi, A. and Provis, J.L. orcid.org/0000-0003-3372-8922 (2017) Calorimetric study of geopolymer binders based on natural pozzolan. Journal of Thermal Analysis and Calorimetry, 127 (3). pp. 2181-2190. ISSN 1388-6150
Abstract
This paper investigates the kinetics of geopolymerisation in an inorganic polymeric binder based on a natural pozzolan. The heat released by the exothermic geopolymerisation reaction process is monitored under isothermal temperature conditions, maintained in a differential scanning calorimeter using a water circulation cell. Calorimetric data are obtained isothermally at 65, 75, and 85 °C with various Na2O/Al2O3 and SiO2/Na2O molar ratios and in the presence and absence of small amounts of calcium aluminate cement (used as an efflorescence control admixture in these binder systems). The first stage of reaction, which is rapid and strongly exothermic, is shortened as the temperature increases. The total heat of reaction increases in the mixes containing calcium aluminate cement, but the apparent activation energy calculated using a pseudo-first-order reaction model is lower than without added calcium aluminate cement. At a constant overall SiO2/Na2O molar ratio, the apparent activation energy is decreased as the Na2O/Al2O3 molar ratio increases. Calcium aluminate cement, therefore, reduces the minimum energy required to initiate geopolymerisation reactions of this natural pozzolan and facilitates the progress of the reactions which lead to formation of a cementitious product.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016 Akademiai Kiado, Budapest . This is an author produced version of a paper subsequently published in Journal of Thermal Analysis and Calorimetry. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Natural pozzolan; Geopolymer; Calorimetry; Kinetic; Activation energy |
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: | 15 Dec 2016 13:47 |
Last Modified: | 14 Nov 2017 10:05 |
Published Version: | https://doi.org/10.1007/s10973-016-5850-7 |
Status: | Published |
Publisher: | Springer Verlag |
Refereed: | Yes |
Identification Number: | 10.1007/s10973-016-5850-7 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:109505 |