621. Lightweight aggregates made from fly ash using the cold-bond process and their use in lightweight concreteAna Frankovič, Violeta Bokan-Bosiljkov, Vilma Ducman, 2017, original scientific article Abstract: Aggregates made from fly ash have been developed by means of the cold-bonding process, with the addition of Portland cement as a binder at (10, 20, and 30) % of mass fractions, and by pouring the mixtures into moulds. After curing for 28 d the samples were processed into aggregate by crushing and sieving. An aggregate containing a weight percentage of 10 % of cement was additionally produced by pelletization on a granulating plate. The density, water-adsorption capacity, porosity, compressive strengths, and frost resistance of the samples were determined. The aggregates prepared by both routes were then used to make concrete samples, whose properties were then compared to those of conventional concrete made using limestone aggregate. The compressive strength of the concrete made with the granulated aggregate reached 16.0 MPa after 28 d, whereas that of the concrete made with crushed aggregate amounted to 24.1 MPa, and that of the conventional concrete was 34.6 MPa.
Keywords: fly ash, lightweight aggregates, density, compressive strength, frost resistance
Published in DiRROS: 14.08.2024; Views: 345; Downloads: 248
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622. An evaluation of marine sediments in terms of their usability in the brick industry : case study Port of KoperPatrik Baksa, Franka Cepak, Rebeka Kovačič Lukman, Vilma Ducman, 2018, original scientific article Abstract: A dredging process is essential for the development of harbours and ports, allowing the functional daily operation of the port. The management of dredged material represents a worldwide challenge, especially considering unwanted deposition of material. Because of their chemical, petrographic, mineralogical and homogeneity composition, marine sediments could represent an appropriate raw material for the brick industry, particularly for the production of clay blocks, roofing and ceramic tiles. In this study dredged material from Port of Koper was tested for such use, thus various analyses were carried out in order to determine if the dredged material is environmentally friendly and suitable for use in the brick industry. These included: chemical analysis, mineralogical analysis, particle size analysis, chloride content analysis and tests of firing in a gradient furnace. Furthermore, tests of mechanical properties, as well as tests of the frost-resistance of the samples were carried out. On the basis of the primary analyses and samples prepared in a laboratory, it was confirmed that marine sediments from the Port of Koper, without any additives are only conditionally suitable as a source material for producing brick products, because without additives they exhibit too much shrinkage on drying and firing, as well as high water absorption, this can be improved by the incorporation of suitable additives, for example, virgin clay or other suitable waste material. The approach described herewith can also be followed to assess sediments from other ports and rivers regarding its potential use in clay brick sector.
Keywords: dredge marine sediment, recycling, clay bricks, mechanical properties, chemical analysis
Published in DiRROS: 14.08.2024; Views: 310; Downloads: 183
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623. Efficiency of FRPU strengthening of a damaged masonry infill wall under in-plane cyclic shear loading and elevated temperaturesPetra Triller, Konrad Kwiecień, Arkadiusz Kwiecień, Uroš Bohinc, BogusŁaw Zając, Marcin Tekieli, Magdalena Szumera, Theodoros Rousakis, Vachan Vanian, Ahmet Tugrul Akyildiz, Alberto Viskovic, 2024, original scientific article Abstract: This paper presents results of in-plane shear tests carried out at the ZAG laboratory in Ljubljana (Slovenia) on a RC frame with masonry infill made of clay blocks (KEBE OrthoBlock). The frame was loaded with constant vertical loads at the top of the columns and then by gradually increasing horizontal cyclic loads at the top beam level. Acquired forces and measured displacements allowed capturing hysteretic behavior for determination of dissipation energy. In addition, two Digital Image Correlation (DIC) systems, Aramis and the CivEng Vision, were used to visualize the behavior of the tested specimens, with an emphasis on computing locally required information about the behavior of highly deformable interfaces. Three types of specimens were tested in-plane: the reference specimen in form of plain RC frame, the reference specimen with constructed masonry infill without any strengthening and the specimen, previously damaged and then strengthened on both sides using glass mesh bonded to the infill and the RC frame using flexible adhesive made of polyurethane matrix (Glass Fiber Reinforced PolyUrethane - GFRPU system). The strengthening process, allowed the specimen to withstand additional cyclic loads, reaching a maximum drift of 3.6 % without serious damage disqualifying the structure from further exploitation. The GFRPU strengthening system was found to be highly effective in preventing infill collapse of damaged masonry infill wall during in-plane loading. Additionally, the results of extended thermal analysis of PU are presented as polymers are, in general, a material, poorly resistant to heat. However, the analyzed PU manifested stable properties up to 200 degrees Celsius, which makes this material promising in civil engineering applications at elevated temperatures.
Keywords: masonry blocks, damaged infill, fiber Reinforced PolyUrethane, external composite strengthening, in-plane shear, thermal tests, DIC measurements
Published in DiRROS: 14.08.2024; Views: 285; Downloads: 194
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624. Tailoring the crystalline and amorphous phase ratios of TiO2 through the use of organic additives during hydrothermal synthesisNejc Rozman, Andrijana Sever Škapin, David Maria Tobaldi, Goran Dražić, Peter Nadrah, 2024, original scientific article Abstract: The photocatalytic properties of TiO2 are primarily determined by its crystallinity and crystalline phase ratios. To improve the photocatalytic properties of TiO2, greater control over the formation of crystalline and amorphous phases during synthesis is therefore required. In this study, we demonstrate how the addition of minute amounts of three organic compounds (isopropanol, acetone and acetic acid) during hydrothermal treatment affects the amorphous and crystalline phase ratios: the addition of isopropanol or acetone accelerates the phase transition from anatase and brookite to rutile, whereas the addition of acetic acid inhibits the transformation of anatase to rutile, increasing the content of amorphous phase compared to samples where no organic compound was added. We show that the combination of the organic compound added, along with the duration of the hydrothermal treatment, can be used to tailor the phase composition of TiO2, so as to obtain either: i) TiO2 with a high content of both rutile and amorphous phase, ii) TiO2 with a high rutile content and iii) TiO2 with different ratios of all four phases, when the duration of synthesis is short (2–4 h). The materials synthesized exhibited high photocatalytic activity (in most cases higher than P25), which is attributed to the beneficial phase composition and high specific surface area.
Keywords: sol-gel processes, X-ray methods, chemical properties, TiO2, photocatalysis
Published in DiRROS: 14.08.2024; Views: 293; Downloads: 283
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625. Scoring system for technical evaluation of technologies for remote monitoring of bridgesMogens Saberi, Kevin McPherson, Fengqiao Zhang, Anna Arvidsson, Simon Fjendbo, Carl van Geem, Maja Kreslin, Andrej Anžlin, 2024, published scientific conference contribution Abstract: Transportation infrastructure demands reliable, cost-effective, environmentally friendly, and safe solutions. It is, therefore, crucial to leverage both the knowledge gained from current practices and the potential offered by emerging technologies. This paper uses the scoring system approached in the INFRACOMS project to offer a framework for asset managers and technology providers to identify areas of improvement and make informed decisions regarding selecting and implementing remote condition monitoring solutions. We focus on two technologies for bridges, like bridge weigh-in-motion and digital inspection and centre around four areas: data analysis, visualisation and integration and potential for practical decision-making. Technologies are evaluated based on their intended use, acknowledging that some may have multiple applications due to novel sensor installations or data interpretation/visualisation methods. Consequently, a technology may undergo multiple appraisals within this system. We showcase the benefits of the scoring system, alignment with specific use cases, and potential for broad applicability.
Keywords: bridge, remote monitoring, scoring system
Published in DiRROS: 14.08.2024; Views: 402; Downloads: 187
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626. Challenges of implementing bridge weigh-in-motion on a century-old steel-riveted railway bridgeDoron Hekič, Mirko Kosič, Jan Kalin, Aleš Žnidarič, Andrej Anžlin, 2024, published scientific conference contribution Abstract: This study explores the challenges and methodologies involved in implementing bridge weigh-in-motion (B-WIM) system on a century-old steel riveted railway bridge. A unique aspect of this study, funded by the EU H2020 Shift2Rail Joint Undertaking, was the adaptation of B-WIM systems to the specific constraints of railway bridges since, traditionally, this technology is used to collect heavy gross vehicle loading data on road bridges. The paper details the experimental setup on an old steel-riveted railway bridge, including sensor placement and calibration processes. It highlights the complexities encountered, such as differences in bridge response due to passenger and other type of trains. It introduces the system calibration strategy using known axle loads from passenger locomotives. The study provides insights into the structural response of old steel bridges under traffic loads, contributing valuable data to the field of railway bridge monitoring and maintenance.
Keywords: bridge, B-WIM, bridge Weigh-in-Motion system, numerical model updating, bridge response measurements, railways
Published in DiRROS: 14.08.2024; Views: 286; Downloads: 219
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627. Load testing of the first stress ribbon bridge in SloveniaĐorđe Đukić, Doron Hekič, Mirko Kosič, Rok Vezočnik, Andrej Anžlin, Andrej Štrukelj, Marjan Pipenbaher, Tomaž Weingerl, 2024, published scientific conference contribution Abstract: Paper presents selected results of the diagnostic load testing of a newly-built footbridge in Novo Mesto, Slovenia. The bridge is significant as the first bridge in Slovenia being built with the stress ribbon technology. The diagnostic load testing took place in March 2023 and comprised of three-stage static load testing, dynamic testing with a light truck driving over artificial obstacles, and measurement of ambient vibrations. The consistency between the actual response of the bridge and the response of the finite element (FE) model, used in the design, was evaluated by comparing vertical displacements from the static load testing, natural frequencies and mode shapes. The comparison of the results indicates a satisfactory agreement between the measurements and the response of the FE model, confirming the appropriateness of the employed FE model.
Keywords: bridge, bridge response measurements, stress ribon, load test
Published in DiRROS: 14.08.2024; Views: 242; Downloads: 171
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628. High-resolution Pan-European forest structure maps : an integration of earth observation and national forest inventory dataJukka Miettinen, Patricia Adame, Radim Adolt, Iciar Alberdi, Oleg Antropov, Ólafur Arnarsson, Rasmus Astrup, Ambros Berger, Jón Bogason, Gherardo Chirici, Luka Krajnc, Mitja Skudnik, 2024, complete scientific database of research data Keywords: uneven-aged forest, lidar data, canopy height model, voxels, canopy height diversity
Published in DiRROS: 13.08.2024; Views: 370; Downloads: 633
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629. Identifying even- and uneven-aged forest stands using low-resolution nationwide lidar dataAnže Martin Pintar, Mitja Skudnik, 2024, original scientific article Abstract: In uneven-aged forests, trees of different diameters, heights, and ages are located in a small area, which is due to the felling of individual trees or groups of trees, as well as small-scale natural disturbances. In this article, we present an objective method for classifying forest stands into even- and uneven-aged stands based on freely available low-resolution (with an average recording density of 5 points/m2) national lidar data. The canopy closure, dominant height, and canopy height diversity from the canopy height model and the voxels derived from lidar data were used to classify the forest stands. Both approaches for determining forest structural diversity (canopy height diversity—CHDCHM and CHDV) yielded similar results, namely two clusters of even- and uneven-aged stands, although the differences in vertical diversity between even- and uneven-aged stands were greater when using CHM. The first analysis, using CHM for the CHD assessment, estimated the uneven-aged forest area as 49.3%, whereas the second analysis using voxels estimated it as 34.3%. We concluded that in areas with low laser scanner density, CHM analysis is a more appropriate method for assessing forest stand height heterogeneity. The advantage of detecting uneven-aged structures with voxels is that we were able to detect shade-tolerant species of varying age classes beneath a dense canopy of mature, dominant trees. The CHDCHM values were estimated to be 1.83 and 1.86 for uneven-aged forests, whereas they were 1.57 and 1.58 for mature even-aged forests. The CHDV values were estimated as 1.50 and 1.62 for uneven-aged forests, while they were 1.33 and 1.48 for mature even-aged forests. The classification of stands based on lidar data was validated with data from measurements on permanent sample plots. Statistically significantly lower average values of the homogeneity index and higher values of the Shannon–Wiener index from field measurements confirm the success of the classification of stands based on lidar data as uneven-aged forests.
Keywords: uneven-aged forest, lidar data, canopy height model, voxels, canopy height diversity
Published in DiRROS: 13.08.2024; Views: 263; Downloads: 659
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630. The ongoing range expansion of the invasive oak lace bug across Europe : current occurrence and potential distribution under climate changeAlbert Ciceu, Flavius Balacenoiu, Maarten De Groot, Debojyoti Chakraborty, Dimitrios N. Avtzis, Marek Barta, Simon Blaser, Matteo Bracalini, Bastien Castagneyrol, Ulyana A. Chernova, 2024, original scientific article Abstract: In recent years, the oak lace bug, Corythucha arcuata, has emerged as a significant threat to European oak forests. This species, native to North America, has in the last two decades rapidly extended its range in Europe, raising concerns about its potential impact on the continent's invaluable oak populations. To address this growing concern, we conducted an extensive study to assess the distribution, colonization patterns, and potential ecological niche of the oak lace bug in Europe. We gathered 1792 unique presence coordinates from 21 Eurasian countries, utilizing diverse sources such as research observations, citizen science initiatives, GBIF database, and social media reports. To delineate the realized niche and future distribution, we employed an ensemble species distribution modelling (SDM) framework. Two future greenhouse gas scenarios (RCP 4.5 and RCP 8.5) were considered across three-time intervals (2021–2040, 2061–2080, and 2081–2100) to project and evaluate the species' potential distribution in the future. Our analysis revealed that significant hotspots rich in host species occurrence for this invasive insect remain uninvaded so far, even within its suitable habitat. Furthermore, the native ranges of Turkey oak (Quercus cerris L.) and Hungarian oak (Quercus frainetto L.) species offer entirely suitable environments for the oak lace bug. In contrast, the pedunculate oak and sessile oak distribution ranges currently show only 40 % and 50 % suitability for colonization, respectively. However, our predictive models indicate a significant transformation in the habitat suitability of the oak lace bug, with suitability for these two oak species increasing by up to 90 %. This shift underlines an evolving landscape where the oak lace bug may exploit more of its available habitats than initially expected. It emphasises the pressing need for proactive measures to manage and stop its expanding presence, which may lead to a harmful impact on the oak population across the European landscape.
Keywords: biological invasion, invasive species, species distribution model, Oak pest, biodiversity impact, European oak forest, Europe, oak forest
Published in DiRROS: 13.08.2024; Views: 273; Downloads: 975
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