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Query: "author" (Nadja Železnik) .

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1.
Optimisation of fly ash pretreatment for mechanical strength and radioactive safety in microwave-irradiated alkali-activated materials : preliminary results
Barbara Horvat, Nadja Železnik, Lara Petrič, Sara Tominc, 2026, published scientific conference contribution

Abstract: The study investigates the optimisation of fly ash (FA) pretreatment for producing alkali-activated materials (AAMs) with high mechanical strength and reduced radioactive content. Three FA conditions were compared: as-received, sieved below 200 μm, and treated thermally at 550 °C. Both the sieving and thermal treatment removed the residual cellulose effectively, enhancing the compressive strength significantly, while the microwave irradiation improved the strength only in the as-received FA containing organic content. Sieving below 200 μm also reduced the detectable radionuclides, providing a simple, energy-efficient and low-carbon approach to synthesising high-performance, radwaste-safe AAMs. The preliminary results highlight sieving as a promising method to produce environmentally sustainable construction materials from radioactive FA.
Keywords: alkali-activated materials, radioactive fly ash, naturally occurring radioactive material, radionuclide separation, microwave irradiation, circular economy
Published in DiRROS: 15.05.2026; Views: 483; Downloads: 403
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2.
Alkali-activated fly ash composites with canine-fibre reinforcement : preliminary results
Barbara Horvat, Nadja Železnik, Lara Petrič, Sara Tominc, 2026, published scientific conference contribution

Abstract: The study investigates alkali-activated fly ash (FA) composites reinforced with keratin-based fibres from Chesapeake Bay Retrievers. To increase reactivity, the FA was milled and sieved below 125 μm, while the fibres were incorporated at two mass ratios (1 m% and 5 m%) relative to the FA as part of the preliminary study. Mechanical tests on 3-day-old composites showed that the addition of 1 m% fibres improved performance significantly, increasing the compressive strength by almost 50% (to ~70 MPa) and bending strength by over 30%. In contrast, the addition of 5 m% fibres resulted in a “hairy”, low-binder structure with reduced geometric density and compressive strength. Nevertheless, the fibre- rich composite displayed a unique cushioning effect that restored shape under cyclic pressure, suggesting potential for non-structural applications such as pathways or insulation. The results demonstrated that small additions of keratin fibres can improve the performance of AAM, but excessive fibre content compromises its strength.
Keywords: alkali-activated materials, fly ash, keratin-based fibres, Chesapeake Bay Retriever, circular economy
Published in DiRROS: 15.05.2026; Views: 449; Downloads: 331
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