Browsing by Author "Perera, DS"
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- ItemAqueous dissolution and immobilisation potential of geopolymers for radioactive ions(Materials Australia, 2007-07-02) Vance, ER; Perera, DS; Aly, Z
- ItemAqueous leachability of geopolymers containing cations Ag, Cd, and Co(The Italian Ceramic Society, 2008-06-29) Perera, DS; Aly, Z; Davis, J; Kurlapski, I; Vance, ER
- ItemAqueous leachability of metakaolin-based geopolymers with molar ratios of Si/Al=1.5-4(Materials Australia, 2007-07-04) Aly, Z; Davis, J; Vance, ER; Perera, DS; Durce, D; Hanna, JV
- ItemAqueous leachability of metakaolin-based geopolymers with molar ratios of Si/Al=1.5-4(Elsevier, 2008-08-31) Aly, Z; Vance, ER; Perera, DS; Hanna, JV; Griffith, CS; Davis, J; Durce, DThe leachability in water of metakaolin based geopolymers with molar ratios of Na/Al = 1 and Si/Al = 1.5-4.0 has been investigated in order to optimise the composition for the immobilisation of nuclear waste. Formulations with Si/Al of around 2 are the most suitable using the ASTM/PCT leach test method. The variability of the leach results is discussed with reference to the microstructure, compressive strength and the degree of polymerisation of the geopolymers as observed here by solid state nuclear magnetic resonance, XRD and infrared measurements. © 2008, Elsevier Ltd.
- ItemComparison of measured aqueous leachabilities of Cs- and Sr- containing metakaolin-based geopolymers using regulatory leaching test protocols(The Italian Ceramic Society, 2008-06-29) Aly, Z; Vance, ER; Perera, DS
- ItemFe speciation in geopolymers with Si/Al molar ratio of ~2.(Elsevier, 2007-05-01) Perera, DS; Cashion, JD; Blackford, MG; Zhang, Z; Vance, ERThe speciation of Fe was studied in metakaolin-based geopolymers to which Fe was added as ferric nitrate solution or freshly precipitated ferric hydroxide. From Mössbauer and near-edge X-ray absorption spectroscopies, coupled with X-ray diffraction and electron microscopy, it was concluded that in as-cured geopolymers the Fe was present in octahedral sites, either as isolated ions in the geopolymer matrix or as oxyhydroxide aggregates which had not reacted with the starting geopolymer components. For material to which iron nitrate was added, heating to 900°C allowed the formation of nepheline and a glass, both of which contained tetrahedrally coordinated, substituted Fe3+. © 2007, Elsevier Ltd.
- ItemFeasibility of incorporating cations and anions expected in radioactive waste streams in metakaolin-based geopolymers.(Electrical Components International, 2007-03-25) Perera, DS; Vance, ER; Aly, Z; Fuchs, A; Kiyama, S; Davis, J; Smith, SV
- ItemGeopolymers as candidates for low/intermediate level highly alkaline waste.(Materials Research Society, 2006-11-27) Perera, DS; Vance, ER; Kiyama, S; Aly, Z; Yee, PGeopolymers should be serious waste form candidates for intermediate level waste (ILW), insofar as they are more durable than Portland cement and can pass the PCT-B test for high-level waste. Thus an alkaline ILW could be considered to be satisfactorily immobilised in a geopolymer formulation. However a simulated Hanford tank waste was found to fail the PCT-B criterion even for a waste loading as low as 5 wt%, very probably due to the formation of a soluble sodium phosphate compound(s). This suggests that it could be worth developing a ìmixedî GP waste form in which the amorphous material can immobilise cations and a zeolitic component to immobilise anions. The PCTñB test is demonstrably subject to significant saturation effects, especially for relatively soluble waste forms.
- ItemGeopolymers for low-level waste immobilization(American Ceramic Society, 2006-10-15) Vance, ER; Blackford, MG; Hanna, JV; Aly, Z; Perera, DS
- ItemGeopolymers sintering by optical dilatometry.(Wiley-Blackwell, 2008-11-16) Kamseu, E; Leonelli, C; Perera, DS
- ItemImmobilisation of cations and anions in geopolymers(Materials Science and Technology (MS&T), 2007-09-16) Vance, ER; Perera, DS; Aly, Z; Walls, P; Zhang, YJ; Cassidy, DJ; Griffith, CS
- ItemPerlite waste as a precursor for geopolymer formation(The Australian Ceramic Society, 2009) Vance, ER; Perera, DS; Imperia, P; Cassidy, DJ; Davis, J; Gourley, JTWaste perlite can be reacted with alkaline solutions to form crystalline zeolite 4A and other minor crystalline phases. The fine majority fraction of the waste was fairly reactive and the coarse fraction largely acted as a filler. This geopolymer had poor compressive strength, but when perlite was used in conjunction with flyash, geopolymers of acceptable mechanical properties could be made. Perlite shows significant reaction with 10 Mol/L NaOH solution at ˜70°C, with hydroxysodalite appearing as a reaction product. © 2009, The Australian Ceramic Society