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Abstract Summary
 
 
 
Conference:   105th Annual Meeting & Exposition  
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Symposium:   20. Ceramic Matrix Composites
Session:   Geopolymer Composites - 1:00:00 PM - 5:00:00 PM 4/28/2003
Abs. Title:   Processing, Microstructure and Properties of Fly Ash Based Geopolymers  
Abstract #:   7456  
 
 
 
 
Type:   Invited
Submitted:   12/1/2002 10:59:30 PM
Status:   Accepted
Scheduled?   Yes
Abstract:   The geopolymerisation of natural aluminosilicate minerals, which cover a wide range of structures, minerals groups, hardness, densities and Al2O3 and SiO2 contents, has been investigated. The study of fifteen selected Al-Si minerals shows that the framework structured Al-Si minerals with a high CaO content and a lower K2O content, have a higher potential to undergo geopolymerisation in KOH solution with resulting geopolymers possessing a higher compressive strength. It is found in this work that the added silicate solution actually catalyses the geopolymerisation and initiates the polymerisation between the large silicate oligomers and the aluminate monomers. The alkalinity M2O/H2O, the ratio of added silicate, the SiO2/M2O ratio, the alkali metal cation K+ and the setting pressure positively affect the geopolymerisation of the stilbite/kaolinite matrix. A method of combining XRD, MAS NMR, SEM/EDX, TEM/EDX and HREM techniques has been established to characterise the structural composition of geopolymers. The results on the geopolymers synthesised from stilbite/kaolinite matrices reveal that the mechanical strength of geopolymers is determined by the gel phase as the binder, the undissolved solid reactants as the filler and the ratio of average surface area and undissolved particles. The mechanisms involved in leaching and geopolymerisation can be explained by the cation anion ion pair theory. The Na+ cation, with a smaller size, better stabilises the smaller silicate oligomers, such as monomer and dimer. K+, possessing a larger size, preferentially coordinates with the larger silicate oligomers, which eventually leads to a higher extent of geopolymerisation.
 
 Abstract Author(s)
 
 
 1   Primary and Presenting   Jannie van Deventer - 1011768
Organization   University of Melbourne
Phone #   +61383446620
Fax #   +61383444153
Professional Title   Foundation Professor of Mineral and Process Engineering
Street Address   Parkville

City   Victoria
State  
Country   Australia
Postal Code  
 
 
 2   Co-Author   Linda Xu - 1011808
Organization   University of Melbourne
Phone #  
Fax #  
Professional Title   Post doctoral Research Associate
Street Address  

City   Parkville
State  
Province   Victoria
Country   Australia
Postal Code   3010
 
 
 3   Co-Author   Grant Luckey - 1011809
Organization   University of Melbourne
Phone #   Tel. : +61-3-8344-7922
Fax #  
Professional Title   Post doctoral Research Associate
Street Address  

City   Parkville, Melbourne
State  
Province   Victoria
Country   Australia
Postal Code   3010
 
 
   

 
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