1. Strength and cost analysis of geopolymer concrete using rice husk ash and GGBS as sustainable cement alternativesNarala Gangadhara Reddy, Veeresh. B. Karikatti, Bheem Pratap, Shabarish V. Patil, Vesna Zalar Serjun, 2026, original scientific article Abstract: The present study aims to develop environmentally friendly concrete by using industrial waste materials, namely ground granulated blast furnace slag (GGBS) and rice husk ash (RHA), to produce green concrete. Geopolymer concrete (GPC) has emerged as an alternative to eliminate the use of cement. The main objective of this study is to design and evaluate geopolymer concrete of M40, M50, and M60 grades. Mixes were prepared by replacing GGBS with RHA at 0%, 10%, 20%, and 30% replacement levels for each grade. The resistance of these mixes against 5% sulphuric acid exposure was also examined. Experiments were conducted to determine compressive strength under different parameters, including NaOH concentration, proportions of RHA and GGBS, and curing duration. Additional tests assessed the effect of acid exposure on strength and weight loss. The cost-effectiveness of GPC production was also compared with that of ordinary Portland cement (OPC). The results revealed that, for all three grades, replacement of GGBS with more than 10% RHA led to a decrease in compressive strength. Furthermore, the production cost of GPC was found to be more economical compared to OPC. Both weight loss and strength loss increased progressively with longer acid exposure. Strength reduction for M40, M50, and M60 grade concretes reached 75.4%, 76.1%, and 79.9%, respectively, when 10% of GGBS was replaced with RHA.
Keywords: geopolymer concrete, rice husk ash, ground granulated blast furnace slag, sulphuric acid, cost analysis
Published in DiRROS: 23.06.2026; Views: 148; Downloads: 141
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2. Micro/meso scale investigations on F-slag sand developed with synergistic use of fly ash and slagKummari Sekhar, Bendadi Hanumantha Rao, 2026, original scientific article Abstract: The present study propounds development of an artificial sand, with a prime aim of exploring a potential substitute for natural river sand. The artificial sand, named F-Slag sand, within the particle size range of 4.75 − 0.075 mm, is developed with the combined use of fly ash (FA) and ground granulated blast furnace slag (GGBS) as binder solids (BS) blended in proportions of 90:10, 80:20, 70:30, 60:40, and 50:50. Pelletization, by employing a custom designed disc pelletizer equipment, and geopolymerization, a process of binding and bonding of FA and GGBS particles to form sand size fractions, techniques are adopted to synthesize F-slag sand. Pelletizer speed of 15 rpm, pelletization duration of 10 min, and alkali activator solution to BS ratio of 0.06 are found optimal to produce the sand. A comprehensive micro/meso-analysis, including 3D computed tomography scan, scanning electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller analysis, and Fourier transform infrared spectroscopy are performed on F-slag sand and attempts are made to interpret macro-applications of it. Demonstrably, the synergistic use of GGBS and FA has completely alleviated the need for elevated curing of sand. The gradational analysis revealed that more than 90% of BS are converted into sand size fractions (4.75 − 0.075 mm). F-slag sand exhibited specific gravity of 2.1, water absorption of 17%, permeability 4.2 × 10− 3 cm/sec, angle of internal friction of 38°, and crushing value of 14.8%. In comparison, river sand showed 2.6, 4%, 3.6 × 10− 3 cm/sec, 39° and 6.3% respectively. The loose and compacted bulk densities of F-slag sand are measured at 698 and 991 kg/m3, which are significantly lower vis-à-vis of river sand (1546 and 1728 kg/m3). Micro-analysis confirms dense, well-bonded particles with meso–macroporous connectivity, indicating enhanced mechanical stability and durability. Moreover, leaching and environmental risk analysis affirms that F-Slag sand poses no ecological threat. The outcome of the study, proposition of a novel construction material, elucidates that F-slag sand could be a potential substitute for river sand in building (concrete, mortar, plastering, lightweight structures), mining (mine backfilling) and environmental (drainage & filter) applications.
Keywords: F-Slag sand, geopolymer-assisted pelletization, artificial fine aggregates, fly ash-slag synergy, micro-meso scale characterization, disc pelletizer
Published in DiRROS: 23.06.2026; Views: 156; Downloads: 136
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3. The influence of processed steel slag additive on brick-making clayMojca Loncnar, Sara Tominc, Lea Žibret, Maruša Mrak, Vilma Ducman, 2026, published scientific conference contribution 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: 226; Downloads: 181
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4. Slate-like alkali-activated roofing tiles produced using copper slag and ground granulated blast furnace slagVilma Ducman, Wolfgang Wisniewski, Afsar Muhammad, Davor Kvočka, Efthymios Tatsis, Lubica Kriskova, 2026, original scientific article Abstract: A new type of slate-mimicking roofing tile based on the alkali-activation of an Fe-rich slag has been developed. The main scientific contribution lies in the targeted valorisation of Fe-rich slag for thin, slate-like roofing elements that must satisfy strict roofing-specific requirements, including a limited thickness, low permeability, freeze–thaw resistance, dimensional stability, and high surface quality. Achieving the required properties and optical appearance necessitated a double-layer setup, where a fibre layer primarily provided the required mechanical properties, while a surface layer ensured the desired optical appearance. The microstructure of the produced roofing tiles was analysed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS) and Hg-porosimetry (MIP), and was compared to reference products on the market. A life cycle assessment (LCA) indicates that the current laboratory-scale production cannot yet compete with established market solutions; however, projected improvements in curing energy efficiency at industrial scale suggest strong potential for environmental competitiveness. Hence these roofing tiles could become an environmentally friendly alternative to current roofing materials. Additionally, a demonstration roof was installed to monitor the long-term performance of the roofing tiles over several years under real seasonal exposure.
Keywords: slag, roofing tiles, slate like tiles, performance
Published in DiRROS: 07.04.2026; Views: 318; Downloads: 200
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5. Utilization potential of steel slag for CO2 sequestration and as a filler aggregate in mortarsMojca Loncnar, Sara Tominc, Lea Žibret, Sabina Dolenec, Maruša Mrak, Vilma Ducman, 2026, original scientific article 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: 370; Downloads: 256
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6. EITRM118891 D4.4.1 : Report on technical & economic analysis of the demonstration resultsVilma Ducman, Anže Tesovnik, Snježana Miletić, Gorazd Žibret, Lubica Kriskova, Christos Georgopoulos, 2024, treatise, preliminary study, study Abstract: The Geological Survey of Slovenia (GeoZS), with the assistance of the ENALOS Research and Development (ENALOS), the Slovenian National Building and Civil Engineering Institute (ZAG) and the Katholieke Universiteit Leuven (KUL), has compiled a report documenting the demonstration and application phase of the project.
This report contains a technical analysis on the materials produced as well as an economic analysis, and thus more accurately calculates the financial benefits of the technology.
Keywords: odpadni materiali, waste materials, alkalijsko aktivirani materiali, alkali activated material, trajnostni pristop, sustainable approach, jeklarska žlindra, steel slag, rdeče blato, red mud
Published in DiRROS: 15.01.2026; Views: 803; Downloads: 0
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8. Temperature performance and rutting prediction of steel slag asphalt mixturesHongwen Du, Qinghao Han, Yunhao Wu, Linhua Ma, Minda Ren, 2025, original scientific article Keywords: road engineering, performance prediction, steel slag–rubber powder-modified asphalt mixture, optimization algorithms
Published in DiRROS: 03.10.2025; Views: 747; Downloads: 396
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9. GEORIS pavers – small scale demonstration within GEORIS projectMojca Loncnar, Lubica Kriskova, Christos Georgopoulos, Dimitra Skentzou, Anže Tesovnik, Vilma Ducman, 2025, published scientific conference contribution 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: 1229; Downloads: 784
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10. Alkali-activated mineral residues in construction : case studies on bauxite residue and steel slag pavement tilesLubica Kriskova, Vilma Ducman, Mojca Loncnar, Anže Tesovnik, Gorazd Žibret, Dimitra Skentzou, Christos Georgopoulos, 2025, original scientific article Abstract: This research aimed to investigate the potential of using alkali activation technology to valorize steel slag and bauxite residue for the production of high-performance pavement blocks. By utilizing these industrial by-products, the study seeks to reduce their environmental impact and support the development of sustainable construction materials. Lab-scale testing showed that bauxite pavers showed a decrease in mechanical strength with increasing replacement of ordinary Portland cement. Partial replacement up to 20% still exceeded 30 MPa in compressive strength. Steel slag-based pavers achieved the 30 MPa threshold required for the application with selected mix designs. Pilot-scale production-optimized formulations and standards testing, including freeze–thaw resistance, confirmed the technical viability of these products. Life cycle analysis indicated a 25–27% reduction in CO2 emissions for slag-based tiles compared to traditional concrete tiles. Moreover, using industrial residue reduced mineral resource depletion. This study examined the properties of the resulting alkali-activated binders, their ecological benefits, and their performance compared to conventional materials. Through a comprehensive analysis of these applications, our research promotes the circular economy and the advancement of sustainable construction products.
Keywords: alkali-activated materials, building materials, bauxite residue, steel slag, pavers
Published in DiRROS: 20.01.2025; Views: 1331; Downloads: 803
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