Strategies to control the high temperature shrinkage of fly ash based geopolymers

Strategies to control thermally induced shrinkage in fly ash based geopolymers are investigated. The useof low (<2) Si:Al ratios in the geopolymer provides superior thermal properties and the addition of fillers delivered additional improvements resulting in impressive thermal resistance. Two the...

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Main Authors: Vickers, Les, Rickard, William D.A., van Riessen, Arie
Format: Journal Article
Published: Elsevier Science 2014
Subjects:
Online Access:http://hdl.handle.net/20.500.11937/37056
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author Vickers, Les
Rickard, William D.A.
van Riessen, Arie
author_facet Vickers, Les
Rickard, William D.A.
van Riessen, Arie
author_sort Vickers, Les
building Curtin Institutional Repository
collection Online Access
description Strategies to control thermally induced shrinkage in fly ash based geopolymers are investigated. The useof low (<2) Si:Al ratios in the geopolymer provides superior thermal properties and the addition of fillers delivered additional improvements resulting in impressive thermal resistance. Two thermally stable inorganic fillers, α-alumina and wollastonite, were used because of their high melting points and relatively low thermal expansion. Shrinkage events at elevated temperatures revealed that samples containing filler exhibited 30–35% less volume shrinkage than the control at 1000 °C. Initial compressive strength was moderate (~30 MPa), but increased markedly when samples were fired in excess of 600 °C >100 MPa). Wollastonite addition also improved the flexural strength of the samples which was attributed to its acicular shape imparting fibre-like qualities. Microstructural investigations showed that unfired samples predominantly consisted of spherical particles coated with reaction product. Firing to 1000 °C converted the morphology to a more compact phase with increased pore size.
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spelling curtin-20.500.11937-370562017-09-13T15:24:46Z Strategies to control the high temperature shrinkage of fly ash based geopolymers Vickers, Les Rickard, William D.A. van Riessen, Arie Shrinkage Fillers Geopolymer Thermal analysis Strategies to control thermally induced shrinkage in fly ash based geopolymers are investigated. The useof low (<2) Si:Al ratios in the geopolymer provides superior thermal properties and the addition of fillers delivered additional improvements resulting in impressive thermal resistance. Two thermally stable inorganic fillers, α-alumina and wollastonite, were used because of their high melting points and relatively low thermal expansion. Shrinkage events at elevated temperatures revealed that samples containing filler exhibited 30–35% less volume shrinkage than the control at 1000 °C. Initial compressive strength was moderate (~30 MPa), but increased markedly when samples were fired in excess of 600 °C >100 MPa). Wollastonite addition also improved the flexural strength of the samples which was attributed to its acicular shape imparting fibre-like qualities. Microstructural investigations showed that unfired samples predominantly consisted of spherical particles coated with reaction product. Firing to 1000 °C converted the morphology to a more compact phase with increased pore size. 2014 Journal Article http://hdl.handle.net/20.500.11937/37056 10.1016/j.tca.2014.01.020 Elsevier Science restricted
spellingShingle Shrinkage
Fillers
Geopolymer
Thermal analysis
Vickers, Les
Rickard, William D.A.
van Riessen, Arie
Strategies to control the high temperature shrinkage of fly ash based geopolymers
title Strategies to control the high temperature shrinkage of fly ash based geopolymers
title_full Strategies to control the high temperature shrinkage of fly ash based geopolymers
title_fullStr Strategies to control the high temperature shrinkage of fly ash based geopolymers
title_full_unstemmed Strategies to control the high temperature shrinkage of fly ash based geopolymers
title_short Strategies to control the high temperature shrinkage of fly ash based geopolymers
title_sort strategies to control the high temperature shrinkage of fly ash based geopolymers
topic Shrinkage
Fillers
Geopolymer
Thermal analysis
url http://hdl.handle.net/20.500.11937/37056