Efflorescence and subflorescence induced microstructural and mechanical evolution in fly ash-based geopolymers

Zhang, Zuhua and Provis, John L. and Reid, Andrew and Wang, Hao (2018) Efflorescence and subflorescence induced microstructural and mechanical evolution in fly ash-based geopolymers. Cement and Concrete Composites, 92. pp. 165-177. ISSN 0958-9465


This paper reports the effects of efflorescence on the microstructural and mechanical properties of fly ash-based geopolymers. Geopolymer pastes manufactured by sodium hydroxide and sodium silicate activation of three Class F fly ashes exhibit varying efflorescence behaviour. The geopolymer derived from sodium silicate activation of fine fly ash, which has a compact microstructure, shows a relatively slow efflorescence rate and low efflorescence potential. The efflorescence occurring on the surface of the geopolymer specimens does not change their mineralogical characteristics. However, the compressive strength development and compressive modulus of geopolymers can be affected through processes related to the loss of alkalis, and also to subflorescence. The phenomenon of subflorescence can be regarded as an extended efflorescence taking place under the surface of the material, leading to crystallisation pressure, which may exceed the tensile strength of hardened binders and generate structural damage.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version, in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials
Date Deposited: 25 Jan 2019 05:57
Last Modified: 05 Feb 2019 02:24
Uncontrolled Keywords: alkali activated cement; fly ash; durability; microstructure; mechanical properties
Fields of Research : 09 Engineering > 0912 Materials Engineering > 091202 Composite and Hybrid Materials
Funding Details:
Identification Number or DOI: 10.1016/j.cemconcomp.2018.06.010
URI: http://eprints.usq.edu.au/id/eprint/35294

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