Thermal Character of Geopolymers Synthesized from Class F Fly Ash Containing High Concentrations of Iron and alpha-Quartz

Volume 7 Issue 1, Pages 81 – 88

William D. A. Rickard, Arie van Riessen, Philip Walls
Published
Online: Nov 19 2008 12:56PM

DOI: 10.1111/j.1744-7402.2008.02328.x

ABSTRACT
This article reports the thermal characteristics of geopolymers prepared
with a class F fly ash containing 15 wt% iron oxide and 20 wt%α-quartz.
The characterization techniques used included dilatometry, TGA, DTA,
XRD, and SEM. Geopolymer specimens were prepared with nominal ratios of
Si:Al=2.3 and Na:Al=0.85. Iron oxide in the fly ash precursor was found
to play a critical role in the thermal expansion and morphology of
geopolymers at temperatures >500°C. Volume changes of quartz on
either side of the α–β phase transition cause only minor variations in
thermal expansion.

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