The effect of curing conditions on the properties of geopolymeric materials derived from fly ash

Title: The effect of curing conditions on the properties of geopolymeric materials derived from fly ash
Author(s): Sindhunata, Grant C. Lukey, Xu Jannie S.J.
Paper category : conference
Book title: International RILEM Symposium on Concrete Science and Engineering: A Tribute to Arnon Bentur
Editor(s): J. Weiss, K. Kovler, J. Marchand, and S. Mindess
Print-ISBN: None
e-ISBN: 2912143926
Publisher: RILEM Publications SARL
Publication year: 2004
Nb references: 23
Language: English

Abstract: The effect of curing temperature, relative humidity, and time on the mechanical properties of alkali-activated fly ashbased geopolymers has been investigated in the current work. It is found that geopolymers cured at an elevated temperature (75°C) show an increase in compressive strength and a decrease in intrinsic permeability compared to materials cured at a lower temperature (50°C and 30°C). The effect of curing relative humidity on compressive strength is found to be not as significant as curing temperature. It is also observed that geopolymers with a higher compressive strength generally exhibit a lower permeability, which is believed to be due to a higher extent of geopolymerisation. SEM analysis shows that the geopolymers studied are a mixture of unreacted fly ash particles and a reacted gel phase. A detailed elemental analysis (SEM/EDS) reveals that there are two predominant gel compositions, one is a gel containing a lower alkali metal (Na+ or K+) composition, which is believed to be the geopolymer gel. The other is a high alkali metal gel which is thought to consist of unreacted excess alkali and other components that precipitate during geopolymerisation. The low alkali metal gel is observed to be dominant when the geopolymer is cured at an elevated temperature. This is postulated to occur because at a higher curing temperature, more energy in the form of heat is supplied to the geopolymerisation system, this results in a greater formation of the geopolymeric precursor and hence a greater extent of reaction.

Online publication: 2004-03-25
Classification: Pore Structure and Curing
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2912143926.011