Fly ash-based geopolymers: the relationship between composition, pore structure and efflorescence

Zhang, Zuhua and Provis, John L. and Reid, Andrew and Wang, Hao (2014) Fly ash-based geopolymers: the relationship between composition, pore structure and efflorescence. Cement and Concrete Research, 64. pp. 30-41. ISSN 0008-8846

Abstract

This study reports the observation of efflorescence in fly ash-based geopolymers. The efflorescence rate strongly depends on the activation conditions; at the same alkali content under ambient temperature curing, NaOH-activated geopolymers show less and slower efflorescence than sodium silicate-activated specimens. Geopolymers synthesised at high temperature exhibit much lower efflorescence than those synthesised at low temperature, except for the sodium silicate-activated samples. The substitution of 20% fly ash by slag reduces the efflorescence rate. A relationship between alkali leaching from monosized fractured particles and 'efflorescence potential' is proposed. Soluble silicate and slag addition are beneficial in reducing efflorescence rate, but have very limited influence on the overall efflorescence potential, as they appear to have a delaying rather than mitigating effect. The partial crystallisation of geopolymers, by curing at high temperature, appears to be the most effective method of reducing the efflorescence potential.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2014 Elsevier Ltd. Permanent restricted access to published version in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Mechanical and Electrical Engineering
Date Deposited: 04 Aug 2014 02:24
Last Modified: 16 Jan 2018 00:50
Uncontrolled Keywords: alkali activated cement; carbonation; durability; fly ash; pore size distribution
Fields of Research : 03 Chemical Sciences > 0303 Macromolecular and Materials Chemistry > 030305 Polymerisation Mechanisms
09 Engineering > 0915 Interdisciplinary Engineering > 091505 Heat and Mass Transfer Operations
03 Chemical Sciences > 0302 Inorganic Chemistry > 030203 Inorganic Green Chemistry
Socio-Economic Objective: B Economic Development > 87 Construction > 8703 Construction Materials Performance and Processes > 870301 Cement and Concrete Materials
Identification Number or DOI: 10.1016/j.cemconres.2014.06.004
URI: http://eprints.usq.edu.au/id/eprint/25682

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