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1451 - 1460 / 2000
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1451.
Application of multivariate statistical methods for determining geochemical trends of elements on the territory of Slovenia
Robert Šajn, Mateja Gosar, Jasminka Alijagić, Tamara Teršič, 2024, original scientific article

Abstract: The main objective of this study is to map multi-element geochemical anomalies in soil on a regional scale. We aimed to determine and evaluate the baseline geochemical values and main geochemical trends in soil that may serve as reference values against any future changes. A total of 817 topsoil samples (0–10 cm) were collected in a 5 × 5 km grid and analyzed for 35 elements using ICP-ES after multi-acid digestions (HClO4/HNO3/HCl/HF) and 53 elements using ICP-MS after modified aqua regia digestion (HCl/HNO3/H2O). The analytical results for the two different digestion methods (multi-acid digestion vs. aqua regia) were also compared for each chemical element. Multivariate statistical methods were applied to identify the geochemical trends and main sources of trace elements over the territory of Slovenia. Based on these results, seven natural and one mixed natural/anthropogenic geochemical association were established. The contents and trends of the determined factors are presented according to 8 natural units, 4 drainage areas, and geological units characteristic of Slovenia. The identified anthropogenic geochemical association combines toxic elements (Ag, Bi, Cd, Hg, P, Pb, S, Sn, and Zn). Increased values of these elements can be found in mining areas and metallurgic centers, in Quaternary sediments of the Sava River, and Adriatic Basin as the consequence of past mining activities and in the Julian Alps, where their origin could be connected to the atmospheric deposition.
Keywords: soil, geochemical mapping, distribution of geochemical elements, factor analysis, cluster analysis
Published in DiRROS: 04.01.2024; Views: 293; Downloads: 74
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1452.
Heavy minerals as indicators of source material in soils on carbonates
Barbara Čeplak, Miloš Miler, Nina Zupančič, Simona Jarc, 2023, original scientific article

Abstract: The origin of the soils formed on carbonate rocks remains uncertain, as they are probably of polygenetic origin. Of particular interest are the elevated contents of some trace elements detected in these soils, as they can hardly be attributed to insoluble residues of carbonate rock. The aim of this study was to uncover the relationship between heavy minerals in bedrock and soil and to identify other sources that influence the mineral and chemical composition of soil. We investigated representative samples of soils and dolomite bedrock as well as sandstones and marlstones from the nearby flysch basin as an expected source of the aeolian contribution. XRD and SEM/EDS showed that mineral diversity is higher in soils compared to the dolomites. Heavy minerals found in dolomite insoluble residue include sphalerite, Ti-oxide (probably rutile), zircon, fluorite, pyrite, minerals of REE phosphates and apatite group, interpreted as terrigenous detrital material. The mineral composition of soil heavy fraction is only partly following insoluble residues of bedrock and indicates possible aeolian contribution. Comparison with nearby flysch sandstones and marlstones showed similarities in mineralogical diversity by the presence of chromite and Fe-Cr(Mn) oxides (probably carmichaelite). Other minerals present in soils and flysch layers, such as Ti-oxide (probably rutile), zircon, REE phosphates, and pyrite grains, however, show similarities in mode of occurrence and transport indications. Signs of aeolian transport on the grains detected in soils were further confirmed by SEM/EDS.
Keywords: Phaeozem, Upper Triassic dolomite, flysch layers, trace elements, SEM/EDS
Published in DiRROS: 04.01.2024; Views: 316; Downloads: 67
.pdf Full text (8,60 MB)

1453.
Initial experiences of the first version of Slovene sustainable building Indicators that are based on Level(s)
Sabina Jordan, Miha Tomšič, Friderik Knez, Marjana Šijanec-Zavrl, 2023, original scientific article

Abstract: To determine the possibilities for the implementation of sustainable building indicators in Slovenia, testing of the first version of the indicators, developed in the CARE4CLIMATE project and based on the EU Level(s) framework, was carried out in 2022. Invited and interested stakeholders of the construction process were provided with video content and instructions on the Slovenian e-platform of sustainable building indicators. In addition, workshops and lectures with individual subjects were also performed. The final phase of the training and testing procedure included a questionnaire, which was used to obtain information about the participants' opinions regarding the indicators. The analysis of the results of the testing, which was focused on level 2, confirmed the key preliminary finding of the development group, namely that currently, due to the lack of certain knowledge, data, and tools, all indicators for this level are not yet feasible in practice. The research also highlighted the greater need for training and specialization of experts in this field. At the same time, it showed that the testing of the first version itself was a big challenge: only 30 experts fully participated and filled out the online questionnaire. This number seems alarmingly low at first glance, but compared to level(s) testing in the EU member states, it is much more than 50 times higher. However, for the further execution of the indicators in Slovenia, it will therefore be necessary to invest a lot of effort and engagement. It is likely that state support will also be needed, for example, in the form of financial mechanisms or incentives and/or legislative background.
Keywords: sustainability, building, indicators, implementation, testing, questionnaire
Published in DiRROS: 04.01.2024; Views: 317; Downloads: 117
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1454.
Vrednotenje vplivov DPN za VE Paški Kozjak na stanje gozda in gozdarstva
Andreja Ferreira, 2023, treatise, preliminary study, study

Keywords: vrednotenje, vplivi, državni prostorski načrt, vetrna elektrarna, gozdovi, gozdarstvo, Paški Kozjak
Published in DiRROS: 03.01.2024; Views: 357; Downloads: 0

1455.
Fertilisation with potato starch wastewater effect on the growth of Scots pine (Pinus sylvestris L.) forest in Poland
Nella Waszak, Filipe Campelo, Iain Robertson, Radosław Puchałka, Fatima-Zahraa El Balghiti, Jožica Gričar, Ali Boularbah, M. Koprowski, 2024, original scientific article

Abstract: Fertilisation is often used to increase plant productivity in agriculture but has also been used in forestry. In our study, Scots pine forest growing in a nitrogen-poor environment was fertilised with NPK post-production wastewater from a potato starch factory. Our research aimed to investigate the dependence of tree growth on different NPK concentrations. Cell characteristics such as cell wall thickness (CWT), lumen diameter (LD) and tree-ring features such as ring width (RW), total number of cells in annual growth (nTotal), earlywood (EW) and latewood (LW) were investigated. Twenty-six years of regular fertilisation of the forest with different doses of wastewater rich in NPK elements have affected the anatomical structure of Scots pine trees. It is presumed that the reduction in CWT and LD on the fertilised site was due to deficiencies in plant water conductivity, which may have occurred due to physiological drought. The influence of nitrogen on unfertilised site from the wastewater area could contribute to the CWT thickening. The results confirm that the use of NPK in excessive doses is detrimental to trees' conductive system.
Keywords: wastewater effluents, forest fertilisation, cell measurements, tree-ring width, wood anatomy
Published in DiRROS: 03.01.2024; Views: 313; Downloads: 172
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1456.
Fibre reinforced alkali-activated rock wool
Majda Pavlin, Barbara Horvat, Vilma Ducman, 2022, published scientific conference contribution

Abstract: Mineral wool, i.e. rock and glass wool, represents considerable challenge after its functional-time runs out due to its small density leading to large volume consumption during transport and in landfills where it usually ends. Because rock wool is mineralogically and chemically a promising precursor material for alkali-activation, it was milled from few centimetres-decimeters long fibres to micron-sized fibres. Since fibres in alkali-activated materials generally show an increase in mechanical strength, especially the bending strength, 1 m% of additional fibres (basalt, cellulose (2 types), glass, polypropylene, polyvinyl alcohol and steel fibres) was used in the alkali mixture, that was curred at 40 °C for 3 days. Time dependence of the mechanical strengths of alkali- activated materials with and without additional fibres was followed. Maximal increase of compressive and bending strength after 28 days was reached with polypropylene fibres, i.e. it was 20% and 30% higher than compressive and bending strength of alkali- activated material without additional fibres respectively.
Keywords: secondary raw material, alkali activated material, foaming, homogenization, mechanical strength
Published in DiRROS: 21.12.2023; Views: 318; Downloads: 110
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1457.
Influence of homogenization of alkali-activated slurry on mechanical strength
Barbara Horvat, Mark Češnovar, Katja Traven, Majda Pavlin, Katja Koenig, Vilma Ducman, 2022, published scientific conference contribution

Abstract: Alkali-activated materials are promising materials for the construction industry due to the accessibility of the precursors, which are mainly secondary industrial by-products, and their cost- effective and energy-efficient production. Although these materials are not new, some of the parameters in the technological process are not yet fully understood and tested. Therefore, in this paper in the means of mechanical strength, the preparation of alkali-activated pastes by using a three-roll mill homogenization method is discussed. The influence of homogenization of alkali- activated slurry has been evaluated on different waste materials (fly ash, fly ash with metakaolin, slag mixture (electric arc furnace slag and ladle slag), glass wool, waste green ceramics), which are treated with different alkali activators (NaOH, commercial sodium silicate solution, laboratory-produced alkali activators based on waste cathode- ray tube glass) with different curing regimes (60 °C and 70 °C) and different drying methods (drying at room temperature, drying at 105 °C). The viscosity of the slurry before homogenization was higher than after homogenization, the distribution of elements was more uniform and the compressive strength higher in all homogenized alkali activated materials, regardless of other parameters.
Keywords: secondary raw material, alkali activated material, foaming, homogenization, mechanical strength
Published in DiRROS: 21.12.2023; Views: 327; Downloads: 105
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1458.
The development and assessment of alkali activated paving blocks
Ana Frankovič, Vilma Ducman, Lubica Kriskova, Efthymios Tatsis, Petrica Petrica, Yiannis Pontikes, 2022, published scientific conference contribution

Abstract: In recent years great attention has been placed by the building sector on alkali-activated technology based on metakaolin, fly ash and ground granulated blast furnace slag (GGBFS), but also on emerging precursors such as by-products from non-ferrous metallurgy. The present work focuses on the development of alkali-activated binders from two slags, one from primary and one from secondary copper production, which were finely milled, blended with GGBFS, and activated with K-based alkali silicate solution with a 1.7 SiO2/K2O molar ratio. The aggregate to paste mass ratio was 2. The mixtures were cast, and cured for a designated time at room temperature and 60% RH. The so-obtained paving blocks were then tested in accordance with European standard for concrete paving blocks. The following properties were measured: splitting tensile strength, abrasion resistance, slip and skid resistance, resistance to freeze-thaw and resistance to freeze-thaw in the presence of de-icing salts. Their properties were compared to those of commercially available concrete paving blocks, and it was found that the performance of the alkali-activated pavers was generally comparable with the concrete pavers, while certain properties (e.g., abrasion resistance, freeze-thaw resistance and freeze-thaw resistance in presence of de-icing salts) were considerably better.
Keywords: slags, alkali activated pavers, properties
Published in DiRROS: 21.12.2023; Views: 235; Downloads: 156
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1459.
Getting more out of existing structures
Martín-Sanz Henar, Konstantinos Tatsis, Domagoj Damjanovic, Irina Stipanović, Aljoša Šajna, Ivan Duvnjak, Uroš Bohinc, Eugen Brühwiler, Eleni Chatzi, 2019, original scientific article

Abstract: Ultra-high-performance fiber-reinforced cement-based composite (UHPFRC) has been increasingly adopted for rehabilitation projects over the past two decades, proving itself as a reliable, cost-efficient and sustainable alternative against conventional methods. High compressive strength, low permeability and high ductility are some of the characteristics that render UHPFRC an excellent material for repairing existing aged infrastructure. UHPFRC is most commonly applied as a surface layer for strengthening and rehabilitating concrete structures such as bridge decks or building slabs. However, its implementation with steel structures has so far been limited. In this work, the UHPFRC strengthening of a steel bridge is investigated both in simulation as well as in the laboratory, by exploiting a real-world case study: the Buna Bridge. This Croatian riveted steel bridge, constructed in 1893, repaired in 1953, and decommissioned since 2010, was removed from its original location and transported to laboratory facilities for testing prior to and after rehabilitation via addition of UHPFRC slab. The testing campaign includes static and dynamic experiments featuring state-of-the-art monitoring systems such as embedded fiber optics, acoustic emission sensors and digital image correlation. The information obtained prior to rehabilitation serves for characterization of the actual condition of the structure and allows the design of the rehabilitation solution. The UHPFRC slab thickness was optimized to deliver optimal fatigue and ultimate capacity improvement at reasonable cost. Once the design was implemented, a second round of experiments was conducted in order to confirm the validity of the solution, with particular attention allocated to the interface between the steel substrate and the UHPFRC overlay, as the connection between both materials may result in a weak contact point. A detailed fatigue analysis, based on updated FEM models prior to and after strengthening, combined with the results of a reliability analysis prove the benefits of adoption of such a solution via the significant extension of the structural lifespan.
Keywords: bridge, steel, UHPFRC, structures
Published in DiRROS: 21.12.2023; Views: 287; Downloads: 112
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1460.
Merjeni in izračunani fotobiološki učinki odbite svetlobe na ljudi
Katja Malovrh Rebec, 2018, original scientific article

Abstract: Pri načrtovanju osvetlitve izračuni le delno napovejo vplive svetlobe na uporabnike prostorov. Svetloba ima namreč poleg dobro poznanih slikovnih učinkov, ki jih možgani interpretirajo na podlagi odzivov čepkov in paličic, tudi neslikovne učinke. Ti ne pripomorejo k orientaciji v prostoru, temveč sporočajo telesu ključne informacije, ki vplivajo na tvorbo hormonov. Vrh te zaznave je v modrem delu spektra vidne svetlobe. Žal delovanja teh fotoreceptorjev še ne opisujemo s parametri, ustaljenimi v praksi projektiranja, zato so vplivi na uporabnike pogosto prezrti. Dodaten izziv pomeni praksa, pri kateri svetlobne učinke preračunavamo v lukse, kar pomeni, da jih množimo s povprečnim človeškim dnevnim vidom. Tak pristop ni primeren za vrednotenje neslikovnih učinkov, ker imajo drugo akcijsko krivuljo. Izmerili smo spektralno sestavo odbitih dnevnih svetlob v modelnem prostoru, ker nas je zanimalo, kakšne razlike nastanejo v slikovni in neslikovni zaznavi, če pobarvamo stene z različnimi barvami. Modra in vijoličasta stena neslikovno stimulirata opazovalca bolj kot slikovno v obeh opazovanih smereh pogleda, oranžna v obeh primerih neslikovno vpliva manj, pri zeleni pa je bila neslikovna zaznava bolj stimulirana od slikovne pri pogledu naprej, pri pogledu v mizo pa je bilo obratno.
Keywords: svetloba, fotobiološki vpliv, spektralna sestava svetlobe, dnevna svetloba
Published in DiRROS: 21.12.2023; Views: 284; Downloads: 98
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