611. Seismic behavior of strengthened URM masonry - an overview of research at ZAGPetra Triller, Miha Tomaževič, Marjana Lutman, Matija Gams, 2017, published scientific conference contribution Abstract: Four experimental campaigns performed at ZAG over almost a decade and dealing with strengthening of masonry using FRPs are briefly presented. The campaigns show in-situ tests on strengthened walls in an actual building, the cyclic shear laboratory tests where different materials and FRP layouts were explored, use of innovative flexible materials instead of mortar or epoxy, and finally the test of a full scale building model where all aspects of strengthening a building using FRPs are investigated.
Keywords: FRP, seismic strengthening, in-situ tests, laboratory tests, full scale tests
Published in DiRROS: 22.08.2024; Views: 254; Downloads: 117
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612. Modelling of deformable polymer to be used for joints between infill masonry walls and R. C. framesMatija Gams, Arkadiusz Kwiecień, Jože Korelc, Theodoros Rousakis, Alberto Viskovic, 2017, published scientific conference contribution Abstract: In the paper an idea to use a deformable polymer material for the joint between R.C. frames and masonry infills is presented. As an early step of testing the idea, experimental tests of the polymer in monotonic uniaxial tension at different load rates are performed and analyzed. The load rates range from very fast (8.3 mm/s) to very slow (0.00083 mm/s). The material exhibits a very strong strain rate effect and viscous behavior. In the second part of the paper a numerical model is developed and implemented into a finite element to simulate the results of the tests. The model is based on a new family of strain measures, called the Darjani-Naghdabadi strain measures and a classical viscosity formulation. Almost perfect model predictions up to collapse at 50-150% elongation are obtained by using calibration based on minimization of error.
Keywords: masonry infills, deformable polymer joint, viscosity, modelling
Published in DiRROS: 19.08.2024; Views: 320; Downloads: 139
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613. Optimizing process parameters of clay-based ceramics with addition of construction and demolition wasteBiljana Angjusheva, Vilma Ducman, Monika Fidancevska, Vojo Jovanov, 2021, original scientific article Abstract: Construction and demolition waste produced in the Republic of North Macedonia remains a major economic and environmental problem because all construction and demolition waste ends up in local dumps or is disposed of in a landfill. The objective of this study was to investigate the influence of the process parameters on the physical and mechanical properties of clay-based ceramics with partial replacement of clay with construction and demolition waste. Determination of the chemical composition of the waste demolition brick using X-ray fluorescence showed that it consisted of different oxides such as SiO2, Al2O3, Fe2O3 and CaO and minor contents of alkaline and earth alkaline oxides. Production of these ceramics was conducted through the consolidation of clay and waste demolition brick with the evaluation of the main process parameters such as sintering temperature [ST], the content of waste demolition brick [WDB] and isothermal period at the final temperature [IP]. The final model equations for density and bending strength dependence of the main process parameters were obtained and presented. The microstructure of the ceramics determined by SEM shows that the waste material is homogeneously dispersed in the clay matrix.
Keywords: CDW, clay, ceramics, properties
Published in DiRROS: 19.08.2024; Views: 358; Downloads: 158
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614. Krožni in nizko-ogljični gradbeni proizvodiJanez Turk, Tajda Potrč Obrecht, Katja Malovrh Rebec, Patricija Ostruh, 2023, treatise, preliminary study, study Keywords: smernica, sekundarni proizvodi, ponovna uporaba, reciklaža, LCA
Published in DiRROS: 19.08.2024; Views: 324; Downloads: 599
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615. Vpliv dodatka nanofibrilirane celuloze na mehanske lastnosti poli(3-hidroksibutirata)Vesna Žepič Bogataj, Erika Švara Fabjan, Ida Poljanšek, Primož Oven, 2017, original scientific article Abstract: Namen prispevka temelji na inovativnem postopku izdelave nanokompozitov na osnovi poli(3-hidroksibutirata) (PHB) in nanofibrilirane celuloze (NFC). Raziskovalno delo obravnava pripravo koncentratnih mešanic PHB-prahu in NFC v vodni raztopini za tehnologijo ekstruzijskega mešanja. Ekstrudat koncentrirane mešanice PHB/NFC je bil nato uporabljen kot dodatek h granulirani obliki PHB pri pripravi brizganih vzorcev z različnimi utežnimi deleži NFC. V prispevku so podane določene omejitve pri predelavi tovrstnih materialov in predlagane uporabne rešitve za njihovo optimiziranje. Morfološke lastnosti nanokompozitnih komponent smo raziskali z elektronsko mikroskopijo (FE-SEM), mehanske lastnosti pa z nateznim preizkusom. Morfološka preiskava koncentratnih mešanic je razkrila prepleteno sestavo celuloznih nanofibril in polimernih kroglic, pri čemer se posamezne fibrile prepletajo v obliki širših pramenov in ustvarjajo videz zamrežene strukture znotraj polimerne komponente. Mikroskopski posnetki nanokompozitnih mešanic in izboljšane mehanske lastnosti izhodnih materialov potrjujejo,da je adhezivni stik med matrično in ojačitveno komponento dosežen, porazdelitev celuloznih nanofibril po polimerni osnovi pahomogena. Nanokompoziti z visokimi utežnimi deleži NFC (10 % utežnega deleža) dosegajo pomembno večje vrednosti modula elastičnosti (Et = 1720 MPa) in raztezka pri pretrgu (b = 3,1 %) ter prenesejo višje pretržne napetosti ( M = 26 MPa) v primerjavi z referenčnim polimernim vzorcem (Et = 1340 MPa;b = 2,4 %; M = 20 MPa). Rezultati študije dokazujejo, da je ob pravilni predpripravi polimernih mešanic in optimizaciji tehnologije ekstruzijske predelave, mogoče izdelati trdne in žilave materiale, pri čemer delež ojačitvene faze narekuje stopnjo izboljšave končnih lastnosti biopolimerne osnove.
Keywords: nanofibrilirana celuloza, poli(3-hidroksibutirat), morfologija, mehanske lastnosti, ekstruzija, tehnologija brizganja
Published in DiRROS: 14.08.2024; Views: 353; Downloads: 176
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616. Comparison of the mineralogy and microstructure of EAF stainless steel slags with reference to the cooling treatmentMojca Loncnar, Ana Mladenovič, Marija Zupančič, Peter Bukovec, 2017, original scientific article Abstract: TIn the present study the differences in the mineralogical composition and microstructure of various types of EAF stainless steel (EAF S) slag with regard to the cooling treatment, the operation practice in an EAF (electric arc furnace) and environmental ageing reactions were evaluated. It was shown that the mineralogy of the investigated EAF S slags varied from one slag to another, depending on the quality of the produced stainless steel. The production process of the treated steel also has a strong influence on the mineralogy of the slags. The conditions during water cooling treatment were not sufficient to prevent the crystallization of primary mineral phases, which occurs predominantly in air-cooled EAF S slags, probably due to the high basicity of the investigated slags. However, the water cooling treatment of hot slag leads to the absence of γ-CaSiO 4 and the formation of secondary mineral phases predominantly calcite, portlandite, ettringite, calcium aluminate hydrate and calcium silicate hydrate. It has been shown that during the environmental ageing test (down-flow column test) secondary mineral phases were formed, which were the same as those formed during the water cooling treatment.
Keywords: electric arc furnace stainless steel slag, cooling path, microstructure, mineralogy
Published in DiRROS: 14.08.2024; Views: 358; Downloads: 210
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617. Characterisation of ground thermal and thermo-mechanical behaviour for shallow geothermal energy applicationsAna Vieira, Maria Alberdi-Pegola, Paul Christodoulides, Saqib Javed, Fleur Loveridge, Frederic Nguyen, Francesco Cecinato, João Maranha, Georgios Florides, Iulia Prodan, Gust Van Lysebetten, Elsa Ramalhosa, Diana Salciarini, Aleksandar Georgiev, Sandrine Rosin-Paumier, Rumen Popov, Stanislav Lenart, Søren Erbs Poulsen, Georgia Radioti, 2017, original scientific article Abstract: Increasing use of the ground as a thermal reservoir is expected in the near future. Shallow geothermal energy (SGE) systems have proved to be sustainable alternative solutions for buildings and infrastructure conditioning in many areas across the globe in the past decades. Recently novel solutions, including energy geostructures, where SGE systems are coupled with foundation heat exchangers, have also been developed. The performance of these systems is dependent on a series of factors, among which the thermal properties of the soil play a major role. The purpose of this paper is to present, in an integrated manner, the main methods and procedures to assess ground thermal properties for SGE systems and to carry out a critical review of the methods. In particular, laboratory testing through either steady-state or transient methods are discussed and a new synthesis comparing results for different techniques is presented. In situ testing including all variations of the thermal response test is presented in detail, including a first comparison between new and traditional approaches. The issue of different scales between laboratory and in situ measurements is then analysed in detail. Finally, the thermo-hydro-mechanical behaviour of soil is introduced and discussed. These coupled processes are important for confirming the structural integrity of energy geostructures, but routine methods for parameter determination are still lacking.
Keywords: hallow geotehermal systems, soil thermal behaviour, laboratory testing, in situ testing, thermo-mechanical behaviour
Published in DiRROS: 14.08.2024; Views: 315; Downloads: 212
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618. Water retention properties of stiff siltBarbara Likar, Vikica Kuk, Karmen Fifer Bizjak, 2017, original scientific article Abstract: Recent research into the behaviour of soils has shown that it is in fact much more complex than can be described by the mechanics of saturated soils. Nowadays the trend of investigations has shifted towards the unsaturated state. Despite the significant progress that has been made so far, there are still a lot of unanswered questions related to the behaviour of unsaturated soils. For this reason, in the field of geotechnics some new concepts are developed, which include the study of soil suction.
Most research into soil suction has involved clayey and silty material, whereas up until recently no data have been available about measurements in very stiff preconsolidated sandy silt. Very stiff preconsolidated sandy silt is typical of the Krško Basin, where it is planned that some very important geotechnical structures will be built, so that knowledge about the behaviour of such soils at increased or decreased water content is essential.
Several different methods can be used for soil suction measurements. In the paper the results of measurements carried out on very stiff preconsolidated sandy silt in a Bishop - Wesley double-walled triaxial cell are presented and compared with the results of soil suction measurements performed by means of a potentiometer (WP4C). All the measurement results were evaluated taking into account already known results given in the literature, using the three most commonly used mathematical models. Until now a lot of papers dealing with suction measurements in normal Consolidated and preconsolidated clay have been published. Measurements on very stiff preconsolidated sandy silt, as presented in this paper were not supported before.
Keywords: peščeni melj, trdni melji, sukcija, Bishop - Wesley triaksialna celica, retencijska krivulja, potenciometer WP4C
Published in DiRROS: 14.08.2024; Views: 307; Downloads: 148
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619. Changes of permeability of nonwoven geotextiles due to clogging and cyclic water flow in laboratory conditionsAnna Miszkowska, Stanislav Lenart, Eugeniusz Koda, 2017, original scientific article Abstract: The use of geotextile filters has been a common application in geo-environmental and geotechnical engineering for decades. The purpose of the present paper is to assess the influence of artificial physical clogging and cyclic water flow on the water permeability characteristics of nonwoven geotextiles used commonly in filter and drainage systems. Despite many studies examining the behavior of soil-geosynthetics, the mechanism of physical clogging is not fully understood yet and remains incompletely defined. Artificial clogging and cyclic water flow tests have been conducted according to a procedure created by the authors. Three nonwoven geotextiles and silty sand were employed in the test series. Hydraulic properties of the tested geosynthetics were determined according to the ISO standard. Filter design criteria are also discussed. The paper also presents the changes of water permeability characteristics due to clogging and cyclic water flow. The results show significant decrease of water permeability coefficients of the tested nonwoven geotextiles after artificial clogging and under cyclic water flow. Furthermore, the clogging mechanism was observed and confirmed by three-dimensional computed tomography.
Keywords: nonwoven geotextile, clogging, cyclic flow, permeability, soil
Published in DiRROS: 14.08.2024; Views: 277; Downloads: 187
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620. Monitoring copper corrosion in bentonite by means of a coupled multi-electrode arrayTadeja Kosec, Miha Hren, Andraž Legat, 2017, original scientific article Abstract: This work focuses in monitoring the corrosion processes on copper in a slightly saline environment under oxic conditions, which simulated the first part of high-radioactive waste disposal in bentonite. Besides coupled multi-electrode arrays (CMEA), also electrochemical impedance spectroscopy measurements were implemented. It was expected that this combination of methods would define the general corrosion rate, as well as the spatio-temporal evolution of anodic and cathodic processes. Anodic currents measured by CMEA showed that the corrosion rates decreased with time. Since maximum anodic activity switched between the electrodes, this situation was not individually valid for all the electrodes. At the end of exposure, different spectroscopic techniques were applied in order to identify the modes of corrosion and types of corrosion products. Uneven general corrosion without evident pits was indicated.
Keywords: copper, bentonite, saline groundwater, coupled multi electrode array, corrosion
Published in DiRROS: 14.08.2024; Views: 398; Downloads: 220
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