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Abstract: 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.
Keywords: alkali-activated material, energy dispersive X-ray fluorescence, X-ray photoelectron spectroscopy, samarium oxide
Published in DiRROS: 15.01.2026; Views: 144; Downloads: 82
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Abstract: Alkali-activated materials have emerged as a promising substitute for ordinary Portland cement (OPC) in various applications. This study explores the use of different monitoring techniques for assessing the long-term corrosion behavior of steel in alkali-activated mortars, which remains relatively understudied. Three types of alkali-activated mortars (AAMs) were prepared, based on fly ash, slag, or metakaolin as the precursor material. The corrosion of embedded steel was investigated under wetting and drying cycles with chloride-containing solution for up to one year. Two unconventional techniques were used to monitor corrosion: coupled multi-electrode array sensors (CMEA) to measure partial currents, and electrical resistance (ER) sensors to track thickness reduction. The ER sensors enabled evaluation of general corrosion rates over time, while CMEA provided insight into corrosion initiation and its spatiotemporal distribution. In addition, the corrosion damage on the embedded steel and sensors was evaluated using X-ray computed microtomography (microCT). Distinct corrosion patterns were observed depending on the precursor material: severe corrosion in metakaolin-based AAMs, localized pitting in slag-based AAMs, and moderate damage in fly ash-based AAMs. The study demonstrates the complementary value of CMEA and ER sensors and highlights the challenges of characterizing the long-term corrosion processes in these alternative binder systems.
Keywords: corrosion, alkali‐activated materials, coupled multi-electrode array (CMEA), electrical resistance (ER) sensor, X-ray computed microtomography (microCT), visual analysis
Published in DiRROS: 27.08.2025; Views: 523; Downloads: 377
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Abstract: Artificial aggregates offer a sustainable solution to large-scale waste utilization and the increasing demand for limited natural aggregates. This study extends the understanding of the production of artificial lightweight aggregates with a variable rotation speed approach based solely on biomass fly ash (BFA) alkali-activated materials (AAMs). Systematic variation of alkali content and solution density at a constant water-to-solids ratio showed that alkali concentration significantly influences granulation beyond what can be explained by water availability. The interplay between alkali activation and carbonation was investigated using different mix designs and curing conditions, as well as comparing simultaneous curing carbonation with post-cure carbonation. The results were evaluated with regard to the effects on the macro- and microstructural properties as well as on the leaching behavior. Prolonged carbonation initiated after aggregate formation resulted in premature depletion of Ca, limiting the development of C-A-S-H gels and increasing microporosity, leading to a reduction in mechanical properties. In contrast, post-curing carbonation maintained a compressive strength of over 1 MPa while still allowing carbonation benefits, resulting in compressive strengths comparable to lightweight expanded clay aggregates. Carbonation also proved to be an effective leaching mitigation strategy by stabilizing heavy metals through both physical encapsulation and chemical pH regulation. These results underline the importance of carbonation timing in high Ca AAMs and highlight lightweight aggregates as a viable pathway for BFA valorization, CO₂ sequestration and sustainable construction applications. This approach offers an alternative valorization strategy for BFA facing regulatory restrictions for direct use in cement, while contributing to carbon capture and circular economy initiatives.
Keywords: artificial aggregates, lightweight aggregates, biomass ash, alkali-activated materials, leaching, carbonation
Published in DiRROS: 18.07.2025; Views: 579; Downloads: 576
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Abstract: The dataset supports the data in the tables and figures in the conference article Mineral waste into alkali-activated pavements (doi: www.doi.org/10.18690/um.fkkt.1.2025.11). It contains measurements of mechanical properties, original data of the XRD analyses as well as results of leaching tests.
Keywords: alkali-activation, pavement slabs, mineral waste, recycling
Published in DiRROS: 09.04.2025; Views: 767; Downloads: 435
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Abstract: Technology of alkali activation is an alternative sustainable approach to producing paving paver, where reactive aluminosilicate precursor undergoes a reaction with an alkaline solution to form binded product. The case study presents the functional usability of a technology as part of the Georis project. The construction pavers are composed of over 75% industrial residues, with the majority of the materials sourced from steel slag industry. Laboratory testing of pavers confirmed the promising mechanical properties, demonstrating high compressive and flexural strength, as well as resistance to frost and abrasion. The results support the feasibility of scaling up from lab-scale to pilot manufacturing. The innovative approach in this project was the pilot production process itself, where more than 20 m² of pavers were manufactured and cured in a mobile unit. To assess their real-world performance, a demonstration case was implemented at the SIJ Acroni courtyard, where the pavers were installed to observe their application in a practical setting and to monitor their long-term durability. The valorisation of residues within GEORIS pavers highlights lower CO₂ emissions compared to conventional cement-based pavers and the potential of technology for industrial symbiosis and circular economy initiatives, making it an attractive solution for environmentally conscious industries.
Keywords: waste materials, alkali activated material, sustainable approach, slag, pavers
Published in DiRROS: 07.04.2025; Views: 769; Downloads: 450
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