Quantitative kinetic and structural analysis of geopolymers. Part 1. The activation of metakaolin with sodium hydroxide

Zhang, Zuhua and Wang, Hao and Provis, John L. and Bullen, Frank and Reid, Andrew and Zhu, Yingcan (2012) Quantitative kinetic and structural analysis of geopolymers. Part 1. The activation of metakaolin with sodium hydroxide. Thermochimica Acta, 539. pp. 23-33. ISSN 0040-6031

Abstract

Isothermal conduction calorimetry (ICC) is used here to measure the kinetics of geopolymerisation of metakaolin by reaction with NaOH solution under a variety of conditions. Three exothermic peaks are observed in the calorimetric curve, and are assigned to the dissolution of metakaolin, the formation of geopolymer with disordered or locally-ordered structure, and finally the reorganization and partial crystallization of this inorganic polymer gels. For the purpose of further quantifying the ICC data, the geopolymeric reaction products are assumed to have an analcime-like local structure, and their standard formation enthalpies are estimated from the available data for this structure. This assumption enables ICC to be used for the first time in a quantitative manner to determine the real reaction kinetics of geopolymerization. Increasing the NaOH concentration up to a molar overall Na/Al ratio of 1.1 is seen to enhance the reaction extent observed at 3 days, up to a maximum of around 40% in the high liquid/solid ratio systems studied here, and accelerates the crystallization process. However, further addition of NaOH does not give any additional reaction within this period, or any further acceleration. Raising the reaction temperature from 25°C to 40°C increases the initial reaction rate but has little effect on the final reaction extent, particularly when Na/Al>1.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2012 Elsevier B.V. Permanent restricted access to published version due to publisher copyright policy.
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Mechanical and Mechatronic Engineering
Date Deposited: 07 Apr 2013 05:17
Last Modified: 11 Aug 2014 03:30
Uncontrolled Keywords: geopolymer; isothermal conduction calorimetry; metakaolin; kinetics
Fields of Research : 03 Chemical Sciences > 0303 Macromolecular and Materials Chemistry > 030305 Polymerisation Mechanisms
09 Engineering > 0912 Materials Engineering > 091201 Ceramics
03 Chemical Sciences > 0306 Physical Chemistry (incl. Structural) > 030601 Catalysis and Mechanisms of Reactions
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970109 Expanding Knowledge in Engineering
Identification Number or DOI: 10.1016/j.tca.2012.03.021
URI: http://eprints.usq.edu.au/id/eprint/21382

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