1. Investigating the synergistic impact of freeze-thaw cycles and deicing salts on the properties of cementitious composites incorporating natural fibers and fly ashIldikó Merta, Vesna Zalar Serjun, Alenka Mauko Pranjić, Aljoša Šajna, Mateja Štefančič, Bojan Poletanovic, Farshad Ameri, Ana Mladenović, 2025, original scientific article Abstract: In cold climates, concrete structures confront durability challenges due to harsh conditions. This study evaluates the effects of incorporating natural fibers, such as hemp and flax fibers (at 1 vol%), and partially replacing cement with fly ash (at 25 and 50 wt%) on the properties of cementitious composites subjected to accelerated aging under freeze-thaw cycles and deicing salts. Findings reveal that natural fibers enhance the freeze-thaw resistance, reducing deterioration (scaling) to 5-8% after 56 cycles. When mortars were subjected to accelerated freeze-thaw cycles, the compressive strength of plain mortar significantly decreased (up to 57%). However, adding natural fibers to the matrix substantially reduced its compressive strength loss. In the case of flexural strength, plain mortars experienced 33% loss, while hemp, flax, and polypropylene fiber mortars showed only 13%, 23%, and 10% losses, respectively. Furthermore, mortars experience a notable enhancement in their energy absorption capacity when reinforced with natural fibers, particularly with hemp fibers (up to 348% higher than plain mortar). Under harsh conditions, hemp and flax-reinforced mortars, with 25wt% fly ash replacement, lose the compressive strength significantly however still demonstrate an alternative to synthetic fibers in terms of flexural strength. Even with 25wt% of fly ash, mortars with natural fiber reinforcement display significantly superior energy absorption capacities compared to plain mortars (up to 48%). Keywords: cementitious composites, natural fibers, freeze-thaw cycles, mechanical properties, mass loss, fly ash Published in DiRROS: 23.12.2024; Views: 219; Downloads: 64
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2. Recycled red mud as an useful geotechnical materialPrimož Pavšič, Marija Đurić, Mateja Košir, Alenka Mauko Pranjić, Ana Mladenovič, Primož Oprčkal, Sara Seršen, Vesna Zalar Serjun, 2024, published scientific conference contribution Abstract: Red mud (RM) is an extractive waste from Bayer process in alumina production. The most conventional methods of RM disposal are tailing dams, or dry storage,both of which raiseenvironmental concerns due to the high alkalinity of RMandthe presence and leaching of potentially hazardous elements (PTEs).Due to its fine-grained nature and poor mechanical properties, as well as leaching of potentially hazardous substances, RM cannot be used by itself. Properties of the RM can be improved, by mixing it with hydraulic or pozzolanic binders, such as calcareous ashes or steelmaking slag, to produce mechanically stable and durable composites for earthworks. On the other hand, RMcan also serve as an immobilization additive for remediation of contaminated soils.Two different approaches for useful utilization of RMare presented based on results of laboratory research and a real case study, opening of new possibilities for conserving natural resources and reducing environmental hazards of RM deposits. Keywords: red mud, recycling, geotechnical composites, environment Published in DiRROS: 30.10.2024; Views: 324; Downloads: 843
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4. Fine particulate matter (PM2.5) exposure assessment among active daily commuters to induce behaviour change to reduce air pollutionAnja Ilenič, Alenka Mauko Pranjić, Nina Zupančič, Radmila Milačič, Janez Ščančar, 2023, original scientific article Abstract: Fine particulate matter (PM2.5), a detrimental urban air pollutant primarily emitted by traffic and biomass burning, poses disproportionately significant health risks at relatively limited exposure during commuting. Previous studies have mainly focused on fixed locations when assessing PM2.5 exposure, while neglecting pedestrians and cyclists, who often experience higher pollution levels. In response, this research aimed to independently validate the effectiveness of bicycle-mounted low-cost sensors (LCS) adopted by citizens, evaluate temporal and spatial PM2.5 exposure, and assess associated health risks in Ljubljana, Slovenia. The LCS quality assurance results, verified by co-location field tests by air quality monitoring stations (AQMS), showed comparable outcomes with an average percentage difference of 21.29 %, attributed to humidity-induced nucleation effects. The colder months exhibited the highest air pollution levels (μ = 32.31 μg/m3) due to frequent thermal inversions and weak wind circulation, hindering vertical air mixing and the adequate dispersion of pollutants. Additionally, PM2.5 levels in all sampling periods were lowest in the afternoon (μ = 12.09 μg/m3) and highest during the night (μ = 61.00 μg/m3) when the planetary boundary layer thins, leading to the trapping of pollutants near the surface, thus significantly affecting diurnal and seasonal patterns. Analysis of exposure factors revealed that cyclists were approximately three times more exposed than pedestrians. However, the toxicological risk assessment indicated a minimal potential risk of PM2.5 exposure. The collaborative integration of data from official AQMS and LCS can enhance evidence-based policy-making processes and facilitates the realignment of effective regulatory frameworks to reduce urban air pollution. Keywords: air pollution monitoring, PM2.5 exposure, citizen science, bicycle-mounted low-cost sensors Published in DiRROS: 30.01.2024; Views: 835; Downloads: 333
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5. Mining waste in circular economy - legislative aspectSenko Pličanič, Ana Mladenovič, Alenka Mauko Pranjić, Petra Vrhovnik, 2020, original scientific article Abstract: One of the common European commitments is a transition towards a green circular economy in which waste is not discarded and considered to be just an environmental problem, but should be recognized as an important potential source of raw materials for industry. In a priority order in waste management activities, introduced by the Waste Directive in 2012, recycling is set just behind the waste prevention and reuse. Many types of waste can be recycled, the most perspective being construction, industrial and mining wastes. The latter are produced and disposed of at mine sites during the excavation and processing of ore and are extremely perspective due to large quantities and remaining of different metals, however still underutilized, with low recycling rate. Many mining wastes are inert and do not releases contaminants into environment, however, some of them are problematic and even require monitoring. Reprocessing of these wastes, which include beneficiation and sequential extraction of valuable metals in the first phase and recycling of residues in both structural and civil engineering in the second phase establishes a zero waste model with several benefits for economy, environment and society. Out of the South-East European countries, North Macedonia has great potential to establish this model. As a consequence of long mining tradition and abundant ore resources, there are many mining and metallurgical tailings, on the other hand vivid economy and numerous sinks for use of recycled materials in construction sector can accommodate these quantities. However, there are open questions in terms of administrative procedures and legislation. What are those obstacles that accompany the smooth establishment of the proposed model from a legislative point of view? This paper deals with the situation in North Macedonia, in terms of opportunities, legislative options and the need to adopt new legislation, taking also into account the current problems in this field in Europe. Keywords: circular economy, zero-waste approach, mining waste, construction sector, legislation, krožno gospodarstvo, pristop ničelnega odpadka, rudarski odpadki, gradbeništvo, zakonodaja Published in DiRROS: 04.12.2023; Views: 688; Downloads: 330
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6. Explore the briefcase - learning about raw materials through non-conventional teaching toolsKim Mezga, Petra Vrhovnik, Dragana Šolaja, Lidia Gullon, Alenka Mauko Pranjić, Ainara Garcia Uriarte, 2019, original scientific article Abstract: We live in a material world where the markets are flooded with all kinds of products. At the same time, we are facing a population growth, as well as a product demand growth. But, are we aware of the raw materials needed for our favourite daily products? In which part of the world are they extracted? Do we recognize the value chains from the mine to the product? And, where do these products end up after we use them? Many school curriculums include this topic only briefly, thus there is a need to raise awareness among youngsters about mining and raw materials in general. EIT RawMaterials funded by the European Commission, is the largest community dealing with raw materials in Europe. One of its main objectives is to raise awareness among general public about the raw materials and their indispensability, about the consequences of their uses, about the mining and production systems as well as about the utilization and recycling. Innovative and attractive pathways are employed in the process. One of the projects bringing raw materials and mining closer to pupils is the BRIEFCASE project. Using non - conventional teaching methods, tools and guided workshops, the project provides pupils with a unique hands - on experience. It draws their attention to raw materials and their applications and helps pupils recognize minerals in products we use every day. Besides emphasizing the importance of minerals in our everyday life and addressing sensible issues like conflict minerals, the consequences of our purchase decisions, the sustainability of mining operations and their environmental implications are also presented. Keywords: Project BRIEFCASE, minerals, raising awareness, non-conventional teaching tools, EIT RawMaterials, award Published in DiRROS: 21.11.2023; Views: 1279; Downloads: 360
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7. Digital twins and road construction using secondary raw materialsSebastjan Meža, Alenka Mauko Pranjić, Rok Vezočnik, Igor Osmokrović, Stanislav Lenart, 2021, original scientific article Abstract: Secondary raw materials (SRMs) tend to be a valuable replacement for finite virgin materials especially since construction works (i.e., building and civil engineering work such as road construction) require vast quantities of raw materials. Using SRM originating from recycling a broad range of inorganic waste materials (e.g., mining waste, different industrial wastes, construction, and demolition waste) has been recognized as a promising, generally more cost-efficient, and environmentally friendly alternative to the exploitation of natural resources. Despite the benefits of using SRM, several challenges need to be addressed before using SRM even more. One of them is the long-term durability and little-known response of construction works built using such alternative materials. In this paper, we present the activities to establish a fully functioning digital twin (DT) of a road constructed using SRM. The first part of the paper is devoted to the theoretical justification of efforts and ways of establishing the monitoring systems, followed by a DT case study where an integrated data environment synthesizing a Building Information Model and monitored data is presented. Although the paper builds upon a small scale, the case study is methodologically designed to allow parallels to be drawn with much larger construction projects. Keywords: digital twins, road construction, circular economy Published in DiRROS: 19.07.2023; Views: 1118; Downloads: 452
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8. Environmental impacts and immobilization mechanisms of cadmium, lead and zinc in geotechnical composites made from contaminated soil and paper-ashMarija Đurić, Primož Oprčkal, Vesna Zalar Serjun, Alenka Mauko Pranjić, Janez Ščančar, Radmila Milačič, Ana Mladenovič, 2021, original scientific article Abstract: Paper-ash is used for remediation of heavily contaminated soils with metals, but remediation efficiency after longer periods has not been reported. To gain insights into the mechanisms of immobilization of cadmium (Cd), lead (Pb), and znic (Zn), a study was performed in the laboratory experiment in uncontaminated, artificially contaminated, and remediated soils, and these soils treated with sulfate, to mimic conditions in contaminated soil from zinc smelter site. Remediation was performed by mixing contaminated soil with paper-ash to immobilize Cd, Pb, and Zn in the geotechnical composite. Partitioning of Cd, Pb, and Zn was studied over one year in seven-time intervals applying the sequential extraction procedure and complementary X-ray diffraction analyses. This methodological approach enabled us to follow the redistribution of Cd, Pb, and Zn over time, thus, to studying immobilization mechanisms and assessing the remediation efficiency and stability of newly formed mineral phases. Cd, Pb, and Zn were effectively immobilized by precipitation of insoluble hydroxides after the addition of paper-ash and by the carbonization process in insoluble carbonate minerals. After remediation, Cd, Pb, and Zn concentrations in the water-soluble fraction were well below the limiting values for inertness: Cd by 100 times, Pb by 125 times, and Zn by 10 times. Sulfate treatment did not influence the remediation efficiency. Experimental data confirmed the high remediation efficiency and stability of insoluble Cd, Pb, and Zn mineral phases in geotechnical composites. Keywords: cadmium, lead, zinc, contaminated soil, paper ash, immobilization mechanisms Published in DiRROS: 04.07.2023; Views: 988; Downloads: 580
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9. Environmental and biological impact of fly ash and metakaolin-based alkali-activated foams obtained at 70°C and Fired at 1,000°CCristina Leonelli, Janez Turk, Giovanni Dal Poggetto, Michelina Catauro, Katja Traven, Alenka Mauko Pranjić, Vilma Ducman, 2022, original scientific article Abstract: Alkali-activated foams (AAFs) are inorganic porous materials that can be obtained at temperatures well below 100° C with the use of inorganic wastes as aluminosilicate precursors. In this case, fly ash derived from a Slovenian power plant has been investigated. Despite the environmental benefits per se, due to saving of energy and virgin materials, when using waste materials, it is of extreme importance to also evaluate the potential leaching of heavy metal cations from the alkali-activated foams. This article presents an environmental study of a porous geopolymer derived from this particular fly ash, with respect to the leachability of potentially hazardous elements, its environmental toxicity as determined by biological testing, and the environmental impact of its production. In particular, attention was focused to investigate whether or not 1,000 °C-fired alkali- activated fly ash and metakaolin-based foams, cured at 70 °C, are environmentally friendlier options compared to unfired ones, and attempts to explain the rationale of the results were done. Eventually, the firing process at 1,000 ° C, apart from improving technical performance, could reinforce heavy metal cation entrapment within the aluminosilicate matrix. Since technical performance was also modified by addition of different types of activators (K-based or Na-based), as well as by partial replacement of fly ash with metakaolin, a life cycle assessment (LCA) analysis was performed to quantify the effect of these additions and processes (curing at 70 ° C and firing at 1,000 °C) in terms of global warming potential. Selected samples were also evaluated in terms of leaching of potentially deleterious elements as well as for the immobilization effect of firing. The leaching test indicated that none of the alkali-activated material is classified as hazardous, not even the as-received fly ash as component of new AAF. All of the alkali-activated foams do meet the requirements for an inertness. The highest impact on bacterial colonies was found in samples that did not undergo firing procedures, i.e., those that were cured at 70 °C, which induced the reduction of bacterial Enterococcus faecalis viability. The second family of bacteria tested, Escherichia coli, appeared more resistant to the alkaline environment (pH = 10–12) generated by the unfired AAMs. Cell viability recorded the lowest value for unfired alkali-activated materials produced from fly ash and K-based activators. Its reticulation is only partial, with the leachate solution appearing to be characterized with the most alkaline pH and with the highest ionic conductivity, i.e., highest number of soluble ions. By LCA, it has been shown that 1) changing K-based activators to Na-based activators increases environmental impact of the alkali-activated foams by 1%–4% in terms of most of the impact categories (taking into account the production stage). However, in terms of impact on abiotic depletion of elements and impact on ozone layer depletion, the increase is relatively more significant (11% and 18%, respectively); 2) replacing some parts of fly ash with metakaolin also results in relatively higher environmental footprint (increase of around 1%–4%, while the impact on abiotic depletion of elements increases by 14%); and finally, 3) firing at 1,000°C contributes significantly to the environmental footprint of alkali- activated foams. In such a case, the footprint increases by around one third, compared to the footprint of alkali-activated foams produced at 70 ° C. A combination of LCA and leaching/toxicity behavior analysis presents relevant combinations, which can provide information about long-term environmental impact of newly developed waste-based materials. Keywords: alkali activated materials, geopolimers, leaching, LCA Published in DiRROS: 20.06.2023; Views: 744; Downloads: 366
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10. Mass concrete with EAF steel slag aggregate : workability, strength, temperature rise, and environmental performanceDavor Kvočka, Jakob Šušteršič, Alenka Mauko Pranjić, Ana Mladenovič, 2022, original scientific article Abstract: Temperature control is the primary concern during the design and construction process of mass concrete structures. As the concrete production has an enormous negative environmental impact, the development of green mass concretes will eventually become as important as the thermal characteristics. Therefore, this paper investigates the use of Electric Arc Furnace (EAF) steel slag aggregate for the partial replacement of the natural aggregate in the production of mass concrete. The impact of EAF steel aggregate on mass concrete workability, strength, and thermal behaviour was analysed. In addition, a cradle-to-gate LCA study was conducted to evaluate the environmental footprint and sustainability potential of the tested mass concrete mixtures. The study results suggest that the use of EAF steel slag aggregate in combination with a low-heat cement with a high content of blast furnace slag can significantly lower the temperature, reduce the environmental impact, and increase the sustainability potential of mass concrete, while at the same time providing sufficient workability and compressive strength. The study results indicate that EAF steel slag can be upcycled into an aggregate for the production of green mass concrete mixtures. Keywords: mass concrete, thermal stress, EAF steel slag, green concrete, LCA, sustainability, open access Published in DiRROS: 31.05.2023; Views: 775; Downloads: 493
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