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Iskalni niz: "avtor" (Milica Rajačić) .

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1.
Radiological characterization of alkali-activated material doped with Sm[sub]2O[sub]3 and its polymerization products
Sanja Knežević, Marija M. Ivanović, Snežana S. Nenadović, Milica Rajačić, Marijan Nečemer, Jelena Potočnik, Miloš Nenadović, 2024, izvirni znanstveni članek

Povzetek: The aim of this study was determination of radiological characterization of alkali-activated material with Sm2O3 and its polymerization products. Alkali-activated materials with 1 wt.% and 5 wt.% addition of Sm2O3 were synthesized and their natural radioactivity was determined. Energy dispersive X-ray fluorescence showed changes in the phase composition, or the formation of stable compounds, at higher temperatures. All samples demonstrated good pozzolanic activity, while the percentage of Sm2O3 was slightly changed. The X-ray photoelectron spectroscopy confirmed that the obtained material has a very low carbon content making it environmentally friendly, due to its low carbon content. A detailed analysis of the oxygen peak indicates variations in the stoichiometry of the oxides, which may affect the changes of natural radioactivity. Scanning electron microscopy confirmed that with the increase in the temperature of the thermal treatment, the opening of the pores in the alkali-activated material occurs, as well as further propagation of reaction that increased porosity and crystallization. Radiological measurement confirmed that examined alkali-activated material is safe for usage and exploitation. It should be emphasized that the presence of artificial radionuclide cesium 137Cs was not detected.
Ključne besede: alkali-activated material, energy dispersive X-ray fluorescence, X-ray photoelectron spectroscopy, samarium oxide
Objavljeno v DiRROS: 15.01.2026; Ogledov: 127; Prenosov: 76
.pdf Celotno besedilo (1,37 MB)
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2.
Potential usage of hybrid polymers binders based on fly ash with the addition of PVA with satisfying mechanical and radiological properties
Miljana Mirković, Ljiljana Kljajević, Sabina Dolenec, Miloš Nenadović, Vladimir Pavlović, Milica Rajačić, Snežana B. Nenadović, 2021, izvirni znanstveni članek

Povzetek: Since recycled technologies usage is mandatory for environmental safety, and in this regard, it is important to examine new materials that can be used in construction and are primarily produced from fly ash. In addition to characteristics such as hardness and compressive strength, the given materials must also be radiologically and environmentally safe. The main concept of engineered geopolymer gel composites based on fly ash residues is focused on developing binder materials via gel formation processes that can replace ordinary cement materials. This study is unique in researching the potential use of fly ash from the Nikola Tesla thermal power plant in Serbia, where the hybrid geopolymeric materials synthesized from fly ash are experimentally examined with the addition 1 wt% and 2 wt% of polyvinyl alcohol (PVA). This paper aims to investigate the structural, morphological, mechanical, and radiological properties of hybrid materials with the addition of PVA and without additive in the period of ageing for 28 days at room temperature. The phase composition was investigated using X-ray powder diffraction (XRPD) analysis, while morphological characteristics of these materials were examined using scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDS). Vibrational spectra of obtained samples are investigated using diffuse reflectance infrared Fourier transform (DRIFT) and Fourier transform infrared (FTIR) techniques. The hardness and compressive strength are also examined, indicating that the 1 wt% addition in geopolymeric matrix results in the best mechanical properties. Radiological measurements of investigated all geopolymer samples show decreasing activity concentrations of radionuclides for 50% compared to fly ash.
Ključne besede: geopolymer gel, inorganic binders, hybrid materials, fly ash, radiological properties, strength, open access
Objavljeno v DiRROS: 12.05.2023; Ogledov: 1491; Prenosov: 858
.pdf Celotno besedilo (1,61 MB)
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