101. Parametarska studija kolničke konstrukcije ojačane geoćelijamaSamo Peter Medved, Bojan Žlender, Stanislav Lenart, 2018, original scientific article Abstract: U radu je prikazano parametarsko ispitivanje kolničke konstrukcije ojačane geoćelijama. Analiza temeljena na metodi konačnih elemenata uključuje model neojačane kolničke konstrukcije te model kolničke konstrukcije ojačane geoćelijama, pri čemu se analiziraju razni položaji, debljine i čvrstoća geoćelija. U okviru modela određen je i očekivani vijek trajanja kolničke konstrukcije. Rezultati parametarskog proučavanja u skladu su s rezultatima analitičkih rješenja, laboratorijskih i terenskih ispitivanja. Dobiveni rezultati upućuju na bitno poboljšanje nosivosti, smanjenje debljine asfaltnih slojeva i povećanje trajnosti kolničke konstrukcije kada je ona ojačana geoćelijama.
Published in DiRROS: 12.12.2023; Views: 199; Downloads: 134
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102. Atmosphere - vegetation - soil interactions in a climate change context; impact of changing conditions on engineered transport infrastructure slopes in EuropeAnh Minh Tang, P. N. Hughes, T. A. Dijkstra, Amin Askarinejad, Mihael Brenčič, Yu Jun Cui, J. J. Diez, T. Firgi, Beata Gajewska, F. Gentile, G. Grossi, C. Jommi, F. Kehagia, E. Koda, H. W. ter Maat, Stanislav Lenart, S. Lourenco, M. Oliveira, P. Osinski, Sarah Springman, Ross Stirling, D. G. Toll, Ursula J. Van Beek, 2018, original scientific article Abstract: In assessing the impact of climate change on infrastructure, it is essential to consider the interactions between the atmosphere, vegetation and the near-surface soil. This paper presents an overview of these processes, focusing on recent advances from the literature and those made by members of COST Action TU1202 - Impacts of climate change on engineered slopes for infrastructure. Climate- and vegetation-driven processes (suction generation, erosion, desiccation cracking, freeze-thaw effects) are expected to change in incidence and severity, which will affect the stability of new and existing infrastructure slopes. This paper identifies the climate- and vegetation-driven processes that are of greatest concern, the suite of known unknowns that require further research, and lists key aspect that should be considered for the design of engineered transport infrastructure slopes in the context of climate change.
Published in DiRROS: 12.12.2023; Views: 178; Downloads: 88
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103. Heavy metal signature and environmental assessment of nearshore sediments: Port of Koper (Northern Adriatic Sea)Nastja Rogan Šmuc, Matej Dolenec, Sabina Dolenec, Ana Mladenovič, 2018, original scientific article Abstract: Heavy metal abundance and potential environmental risks are reported for surface sediments (n = 21) from the Port of Koper area, Republic of Slovenia. The enrichment factor (EF) indicates minor enrichment in arsenic (As), cadmium (Cd), copper (Cu), molybdenum (Mo), lead (Pb), antimony (Sb), and zinc (Zn), moderately to severely enriched with nickel (Ni). The trace metal chemistries, in the context of sediment quality guidelines (SQG), imply adverse threshold effect concentrations (TEC) and probable effect concentrations (PEC), for Ni only. Sediment sequential leaching experiments demonstrated that the majority of heavy metals were of natural lithogenic origin and low bioavailability. The heavy metals’ potential for “Risk Assessment Code” values exhibited no or low anthropogenic environmental burden, with the exception of Mo.
Keywords: port sediments, heavy metals, chemical speciation, risk assessment, Northem Adriatic Sea
Published in DiRROS: 12.12.2023; Views: 208; Downloads: 114
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104. Evaluation of ash pozzolanic activity by means of the strength activity index test, frattini test and DTA/TG analysisSabina Dolenec, Vilma Ducman, 2018, original scientific article Abstract: The pozzolanic activity of five different types of ash was studied using various direct and indirect methods. In addition to strength activity index (SAI) determination and the Frattini test, ash pozzolanicity was assessed via differential thermal and thermogravimetric analyses (DTA/TG) after curing for 7, 28 and 90 days. The results showed that, due to their respective mineralogical, chemical and physical characteristics, the ashes exhibited different levels of pozzolanic activity in terms of the amount of lime with which they could chemically bind, as well as reaction kinetics. Although SAI and Frattini test results were not in agreement in the case of some of the ashes, DTA/TG analysis revealed that a certain amount of portlandite was consumed, thus confirming the occurrence of a pozzolanic reaction. The results also showed that ashes with higher amounts of reactive SiO2 were more reactive, while those with higher BET surface areas displayed a faster pozzolanic reaction rate.
Keywords: biomass ash, DTA/TG, fly ash, Frattini test, pozzolanic activity, SAI
Published in DiRROS: 11.12.2023; Views: 223; Downloads: 107
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105. Revitalised geotourism mining heritage potentials in the Posavje FoldsMateja Golež, 2018, original scientific article Abstract: The territory of the Posavje Folds offers many geotourism potentials reflecting in particular in rich mining heritage. For a long time, local communities have considered them mainly in the context of local problems, but nowadays we may see individual examples of successful revitalization of cave chambers and mining structures. All that has given rise to fantastic stories about the mining wealth of the underground world and the mining heritage interpreted with modern approaches and new findings. In addition to managers and heritage owners, the revitalization process also includes scientists, artists, architects and educators who, each in their own way, contribute to a holistic perspective of the values of the past in light of contemporary understanding of this type of heritage. As a result, the territory has witnessed the revitalization of the medieval lead and silver mine Padež pri Laškem, the former Laško coal mine machine room, which was transformed into the Strojnica Gallery, and the polymineral mine Sitarjevec within the last five years. All mentioned examples are cases of abandoned mining activities with long-lasting mining tradition, which left an imprint in the area in terms of the diverse social structure of the population and in terms of town development, which also allows us to evaluate from a distance the contribution to the construction of the railway between Vienna and Trieste, which put these towns on the European map of centres of industrial significance in the mid-19th century. Trains that still connect the Austrian capital with the Adriatic coast may in future, in light of sustainable green tourism, attract curious guests to stop and linger a while, which is the ultimate goal of the attempts of local communities to revitalise mining heritage. Meanwhile, the goals set can only be realised with the help of new and attractive tourist products that reflect own creativity related with tradition ranging from design ideas, music events, art installations, popular science evenings; in short, with contents that are suited to visitors of all ages.
Keywords: mines, heritage, revitalisation, geoturism
Published in DiRROS: 11.12.2023; Views: 228; Downloads: 88
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106. Quantified joint surface description and joint shear strength of small rock samplesKarmen Fifer Bizjak, Andraž Geršak, 2018, original scientific article Abstract: Geotechnical structures in rock masses such as tunnels, underground caverns, dam foundations and rock slopes often have problems with a jointed rock mass. The shear behaviour of a jointed rock mass depends on the mechanical behaviour of the discontinuities in that particular rock mass. If we want to understand the mechanical behaviour of a jointed rock mass, it is necessary to study the deformation and strength of a single joint. One of the primary objectives of this work is to improve the understanding of the frictional behaviour of rough rock joints under shear loads with regard to the roughness of the joint surface. The main problem is how to measure and quantify the roughness of the surface joint and connect the morphological parameters into a shear strength criterion. Until now, several criteria have been developed; however, all of them used large rock samples (20×10×10 cm). It is often not possible to get large samples, especially when the rock is under a few meters thick layer of soil. In this case, samples of rock can only be acquired with investigation borehole drilling, which means that the samples of rock are small and of different shapes. The paper presents the modified criterion that is suitable for calculating the peak shear stress of small samples.
Keywords: camera-type 3D scanner, rock mechanics rock joint, roughness of the joints, rock joint shear strength
Published in DiRROS: 11.12.2023; Views: 210; Downloads: 93
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107. Pathway toward sustainable winter road maintenance (case study)Katja Malovrh Rebec, Janez Turk, 2023, independent scientific component part or a chapter in a monograph Abstract: Life Cycle Assessment (LCA) method was applied to evaluate the environmental impacts of winter road maintenance managed by an innovative road-weather information system and the impacts of vehicles passing the road during the snowstorm event. A case study refers to 10-hour lasting snowstorm event, considering a specific road section and application of a road-weather information management system to help winter road maintenance agency optimizing activities (salt gritting and/or plowing). Reliable information on the timing of the beginning of the snowstorm event affects (1) the activities of winter road maintenance, (2) the mobility of all vehicles passing the road, and (3) the fuel consumption of the vehicles. Since activities are optimized in case of preventive operation of winter road maintenance, less salt is needed overall. The road remains free of snow cover in case of preventive winter road maintenance operation, meaning that passenger cars and trucks pass the road at normal speed, without undesirable acceleration and braking caused by wheels slipping if snow accumulates on the road. Fuel consumption of vehicles passing salted and snow-free road remains unchanged, while fuel consumption increases in case of snow cover. Reduction of environmental burdens in case of such optimized winter road maintenance operation, is shown in this case study. The overall results of the comparative LCA analysis showed that the use of the road-weather information system in road traffic allows for as much as 25% reduction of environmental footprints. In the scenario where the winter service does not use information system the winter service also uses 40% more salt, which is also related with additional environmental impacts.
Keywords: LCA, okoljski odtisi, cesta, snežne razmere, preventivno delovanje, promet, poraba goriva, varnost, LCA, environmental impacts, road, snow cover, preventive operation, traffic, fuel consumption, safety
Published in DiRROS: 11.12.2023; Views: 191; Downloads: 136
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108. Experimental study and thermodynamic modelling of the temperature effect on the hydration of belite-ye’elimite-ferrite cementsMaruša Mrak, Frank Winnefeld, Barbara Lothenbach, Andraž Legat, Sabina Dolenec, 2024, original scientific article Abstract: This study focuses on the kinetics of hydration, phase assemblage, microstructure and mechanical properties after various hydration times of two different BCSA cements at 5, 20, 40 and 60 ◦C and compares experimental data with thermodynamic modelling. Different curing temperatures change the type of hydrates and their amounts. Ye’elimite and gypsum in belite-ye’elimite-ferrite cements are almost fully reacted after 24 h of hydration at 20, 40 and 60 ◦C, while not at 5 ◦C. The hydration of belite is slower than the one of ye’elimite, but reaches a high degree of hydration after 150 days which is increasing with temperature. Less ettringite is present at elevated temperatures due to its increasing solubility, while more monosulfate is observed. Furthermore, with increasing temperature siliceous hydrogarnet forms at the expenses of strätlingite as well as more C S H is found as more belite reacts resulting in higher compressive strength. Dense and homogenous microstructure is observed at 5 ◦C, while it is more heterogeneous at higher temperatures. The presence of more ye’elimite resulted in higher ettringite and str¨atlingite formation and a higher compressive strength, while more belite yields more C S H in the hydrates and lower compressive strength.
Keywords: belite-ye’elimite-ferrite cement, temperature, hydration, thermodynamic modelling
Published in DiRROS: 11.12.2023; Views: 179; Downloads: 149
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109. Uporaba sistemov za tehtanje vozil med vožnjo za določitev realne konstrukcijske varnosti mostovAleš Žnidarič, Maja Kreslin, Jan Kalin, Andrej Anžlin, 2019, original scientific article Abstract: Optimalno upravljanje mostov, ki vključuje stroške vzdrževanja, potencialna tveganja in vzdrževanje funkcionalnosti, zahteva natančne informacije o stanju konstrukcij. Eden od ključnih kazalnikov obnašanja je konstrukcijska varnost mostu, ki zahteva poglobljeno poznavanje prometnih obremenitev in njegove odpornosti proti obremenitvam. Vrednotenje varnosti je predvsem ključno za stare mostove, ki so poškodovani in se bližajo koncu življenjskega cikla. Varnost takšnih mostov z uporabo tradicionalnih računskih metod pogosto težko dokažemo. Da bi se izognili nepotrebnim ukrepom, kot je ojačitev ali celo zamenjava mostu, je priporočljivo narediti celovito analizo, ki vključuje preiskave materialov in meritve obnašanja mostu pod prometno obtežbo. Prispevek predstavlja tehnologijo tehtanja vozil med vožnjo v prostem prometnem toku na mostovih (angl. bridge weigh-in-motion oz. B-WIM), ki lahko učinkovito izmeri parametre obnašanja mostu, ki so ključni za določitev njihove realne varnosti: osne obremenitve in medosne razdalje vozil ter vplivnice, faktorje porazdelitve obtežbe in dinamični odziv konstrukcije. Poznavanje pravih vrednosti teh parametrov zmanjšuje negotovosti, povezane z obremenitvami in odzivom konstrukcije. Poleg tega lahko zaradi večje zanesljivosti izmerjenih parametrov v analizah zmanjšamo varnostne faktorje. To omogoča bolj optimalno vzdrževanje in uporabo infrastrukture ter racionalnejšo uporabo razpoložljivih finančnih sredstev.
Keywords: upravljanje mostov, konstrukcijska varnost, odziv na prometno obtežbo, tehtanja vozil med vožnjo, prosti prometni tok na mostovih
Published in DiRROS: 04.12.2023; Views: 272; Downloads: 102
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110. Reološko ovrednotenje alternativnega pomlajevalca, pridobljenega iz odpadnih snoviLidija Ržek, 2019, original scientific article Abstract: Zaradi sodobnega načina življenja je nastanek odpadkov neizogiben. Vse večja okoljska ozaveščenost, predvsem pa tržna naravnanost in ekonomičnost nas spodbujajo, da odpadke obravnavamo kot vir za nadaljnjo oz. ponovno uporabo. V raziskavi smo izdelali alternativni pomlajevalec iz odpadnih gum in pokazali, da lahko povrne prvotne lastnosti laboratorijsko postaranemu bitumnu. S postopkom pirolize smo izdelali več različnih produktov tako, da smo spreminjali čas trajanja in temperaturo pirolize. Med novo razvitimi produkti smo izbrali najprimernejšega za namen alternativnega pomlajevalca in preverjali njegov vpliv v različnih koncentracijah (3 %, 5 %, 10 % in 20 % glede na maso bitumna) na lastnosti svežega in laboratorijsko staranega bitumna. S pomočjo standardnih mehanskih raziskav, reoloških raziskav in reološkega modeliranja smo dokazali, da alternativni pomlajevalec izboljša lastnosti staranega bitumna.
Keywords: pomlajevalec, piroliza, asfaltni granulat, reologija, visokoelastične lastnosti
Published in DiRROS: 04.12.2023; Views: 265; Downloads: 82
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