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Abstract: As clay deposits become scarce, the brick industry is increasingly seeking additives or substitutes. This study investigates a high- plasticity clay that requires an opening agent, for which was used 10 wt.% of processed steel slag Ekominit S1. Ceramic- technological tests were performed to determine the compressive strength, density and porosity. The addition of Ekominit S1 increased the total porosity by 5% in samples fired at 950 °C, and by 4% in samples fired at 1050 °C, while the compressive strength decreased by 36% in the samples fired at 950 °C and by 38% in those fired at 1050 °C compared to the reference material. Although the mechanical properties were lower than those of the reference, the benefit is reduced shrinkage. The processed steel slag could be incorporated successfully into bricks, which would also reduce the environmental impact of this sector by using secondary products instead of virgin materials.
Keywords: clay bricks clay bricks, compressive strength, porosity, opening agent, steel slag
Published in DiRROS: 15.05.2026; Views: 259; Downloads: 205
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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: 343; Downloads: 269
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Abstract: Steel slag is an abundant by-product of steelmaking and a promising candidate for CO2 sequestration due to its favorable chemical composition and mineralogy. In this study, the CO2 sequestration capacity of the processed steel slag Ekominit was analyzed. Ekominit is a mineral product obtained by processing a mixture of electric arc furnace (EAF) stainless steel slag and ladle slag, currently used only for simple engineering constructions. The study demonstrated a promising sequestration capacity of 127.4 g CO2 per kg of Ekominit, measured using direct semi-dry carbonation under ambient pressure at 40 ± 0.5 °C, 80 ± 3.2% relative humidity, and 20 ± 0.1 vol% CO2 for 5 days, which is within the typical range reported for carbonated steel slags (100–150 gCO2/ kgslag). Although Ekominit did not show sufficient potential as a supplementary cementitious material in mortar, the results confirmed that its incorporation as a filler—with or without carbonation treatment—enhances both the flowability and compressive strength of the mortar. This research emphasizes the dual-function potential of Ekominit: it captures CO2, contributing to the decarbonization of the steel sector, and enables its reuse in construction materials, even improving the performance of mortars when using such carbonated Ekominit as fillers. Through such industrial symbiosis, environmental impact is further reduced by substituting virgin raw materials with secondary products.
Keywords: slag, carbonation, sequestration, aggregates
Published in DiRROS: 06.03.2026; Views: 420; Downloads: 284
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Abstract: The dataset supports the data presented in the tables and figures of the conference paper "Mineral CO2 sequestration in industrial waste materials: a comparative study using FTIR, TGA and calcimetry" (https://doi.org/10.18690/um.fkkt.1.2026.8). It includes masses before and after carbonation treatment, calcimetric measurements, XRF, TGA, FTIR and XRD analysis data, as well as calculations of CO2 uptake and CO2 sequestration capacity for the analysed samples.
Keywords: alkali-activated materials, biomass ash, carbonation, artificial aggregates, alkalijsko aktivirani materiali, biomasni pepel, karbonatizacija, umetni aggregati
Published in DiRROS: 04.12.2025; Views: 425; Downloads: 165
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Abstract: Clay-based materials typically require high-temperature processing (>900 ◦C), resulting in high energy consumption. This study explores cold sintering of metakaolin (MK) powders to achieve high mechanical strength at significantly lower processing temperatures. By applying uniaxial pressure of 400 MPa and heating to only 240 ◦ C in the presence of 15 mol/L NaOH solution, successful densification of structurally sound and dense samples with an average density of 2.16 g/cm³ and a biaxial flexural strength of ~35 MPa was achieved. This strength surpasses that of conventionally sintered MK (1470 ◦C) by ~30 %. Densification was found to be governed by synergistic mechanisms involving MK exfoliation, conformal sintering around aggregates, and the precipitation of an amorphous sodium aluminosilicate hydrate phase. Crack formation was avoided through process optimization and verified using X-ray micro-computed tomography. These findings offer new insights into the chemo- mechanical mechanisms of cold sintering and demonstrate its potential as an efficient route for producing structural materials.
Keywords: cold sintering, metakaolin, geopolymer, delaminations, exfoliation
Published in DiRROS: 15.10.2025; Views: 700; Downloads: 388
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