Pages: 66-73

Authors: Miloš T. Nenadović, Claudio Ferone, Ljiljana M. Kljajević, Miljana M. Mirković,
Bratislav Ž. Todorović, Ivana S. Vukanac, and Snežana S. Nenadović

Abstract

Presented study deals with the final structure and radiological properties of different fly-ash based geopolymers. Lignite fly-ash (lignite Kolubara – Serbia) and wood fly ash were obtained in combustion process together with commercial fly-ash. Synthesis of the geopolymers was conducted by mixing fly-ash, sodium silicate solution, NaOH and water. The samples were strengthened 60 °C for 48 hours after staying at room temperature in covering mold for 24 hours. The X-ray diffraction, Fourier transform infrared and SAM measurements were conducted on the samples after 28 days of geopolymerization process. The X-ray diffraction measurements of lignite fly-ash samples show anhydrite as the main constituent, while wood fly-ash samples consist of calcite, albite and gypsum minerals. Besides determination of physicochemical properties, the aim of this study was radiological characterization of lignite fly-ash, wood fly-ash and the obtained geopolymer products. Activity concentration of ⁴⁰K and radionuclides from the ²³⁸U and ²³²Th decay series, in ash samples and fly-ash based geopolymers, were determined by means of gamma-ray spectrometry, and the absorbed dose rate, D, and the annual effective dose rate, E, were calculated in accordance with the UNSCEAR 2000 report.

Key words: fly-ash, lignite, wood, geopolymerization, radionuclide

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