Optimisation of fly ash pretreatment for mechanical strength and radioactive safety in microwave-irradiated alkali-activated materialsHorvat, Barbara (Avtor) Železnik, Nadja (Avtor) Petrič, Lara (Avtor) Tominc, Sara (Avtor) alkali-activated materialsradioactive fly ashnaturally occurring radioactive materialradionuclide separationmicrowave irradiationcircular economyThe 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.University of Maribor, University of Maribor Press, University of Maribor, Faculty of Chemistry and Chemical Engineering20262026-05-15 13:09:24Neznano29402UDK: 620.1/.2DOI: 10.18690/um.fkkt.1.2026.2COBISS_ID: 276254723OceCobissID: 272982019sl© authors of proceedings and Potrč, Bogataj, Kravanja, Novak Pintarič (editors)