20.500.12556/DiRROS-25265 Hydration and carbonation behaviour of selected recycled materials from Slovenia The European Union’s shift towards a circular economy emphasizes the substitution of virgin materials with recycled alternatives, particularly in the construction sector, which can accommodate large volumes of industrial by-products. Ashes from coal, biomass, paper sludge, and co-combustion processes are abundant secondary materials whose variable chemical and mineralogical compositions necessitate careful assessment to enable safe and effective reuse.This study investigates the hydration behaviour and early carbonation potential of ashes of different origin. The ashes were characterized using X-ray fluorescence, X-ray diffraction, and scanning electron microscopy coupled with energy-dispersive spectroscopy. Hydraulic reactivity was evaluated by preparing ash pastes at a 1:1 water-to-ash ratio and monitoring hydration product formation over time using XRD. Carbonation of co-combustion ash was studied under controlled CO₂ conditions (2 % CO₂, 50 % RH, 20 °C ± 1 °C) at different moisture contents (0 wt.%, 10 wt.%, 20 wt.%, and 40 wt.%) and early curing times (0 hours, 1 hours, 4 hours, and 24 hours).Results indicate distinct differences among the ashes. Paper sludge ash exhibited the most extensive formation of calcium aluminate hydrates, coal and co-combustion ashes showed moderate hydration, while biomass ash produced only minor secondary phases. Carbonation of co-combustion ash proceeded concurrently with hydration, with lime depletion and calcite formation enhanced by higher moisture and longer curing. These coupled processes influenced both the kinetics and composition of hydration products. The findings demonstrate the potential of diverse combustion ashes for valorisation in construction materials and provide insight into their reactivity under early-age hydration and carbonation conditions, supporting circular economy initiatives. circular economy ashes from combustion hydraulic activity carbonation phase composition amorphous phase krožna ekonomija pepeli iz sežiga hidravlična aktivnost karbonatizacija fazna sestava amorfna faza true false true University of Zagreb, Faculty of Mining, Geology and Petroleum Engineering Angleški jezik Slovenski jezik Copyright (c) 2025 author(s) and publisher Neznano 2026-01-14 13:54:28 2026-01-14 13:57:53 2026-01-15 03:49:00 0000-00-00 00:00:00 2025 0 0 Str. [181-186] 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2025-10-15 620.1/.2 261918723 260319747 https://hrcak.srce.hr/omp/index.php/rgn-unizg/catalog/book/399 1 2bcce8b8-f148-11f0-94a7-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=38151 RAZ_Zalar_Serjun_Vesna_2025.pdf RAZ_Zalar_Serjun_Vesna_2025.pdf 1 AEC8248C6D732689606362B7B77DE71D e85a5804cb09fb5076b21a8760618a8ba6db0d253152d8c433eda71a162f91b5 9f8e13f8-f148-11f0-94a7-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=38156 Zavod za gradbeništvo Slovenije 0 0 0