811. Thermal insulation and flammability of composite waste polyurethane foam encapsulated in geopolymer for sustainable building envelopeBarbara Horvat, Nataša Knez, Uroš Hribar, Jakob Koenig, Branka Mušič, 2024, original scientific article Abstract: Polyurethane foam (PUR) is a lightweight, thermally insulating, widely used, and highly flammable material that has after its use an adverse effect on the environment, i.e., PUR disposal is considered hazardous. Its flammability can be mitigated using various fire retardants, but they do not change the hazardous nature of waste PUR. Therefore, in the current study, waste PUR with and without flame retardants based on N and P was incorporated into a geopolymer, the alkali-activated material (AAM) based solely on metakaolin, to evaluate the potential recycling route of waste PUR while taking into account its flammability, so it can enter safely into the circular economy through the building industry. To enhance the mechanical properties of the composite, a fresh mixture was irradiated with microwaves. However, the irradiation of geopolymer containing PUR negatively influenced mechanical performance, which led to the evaluation of the behaviour of the complex dielectric constant of PUR and fire retardants. Materials and composites were evaluated regarding their chemistry, mineralogy, microstructure, and porosity to connect the structure with extrinsic properties like geometrical density, thermal conductivity, and fire properties. Nonetheless, positive influences of PUR being encapsulated in the geopolymer were lowered density (from 1.8 to 1.6 kg/l) and improved thermal insulation ability (from 940 to 860 mW/(m·K)) of the composites: with the inclusion of <5 % of PUR, thermal insulation improved by nearly 10 %. However, the contribution of PUR to the composite originated from its skeleton, which has more than 15 times bigger geometrical density (0.81 kg/l) compared to the density of the skeleton (0.047 kg/l). This offers an open field for further advancements of thermal properties, but would also lead to a decrease of the compressive strength, which was already lowered from 90 MPa for 30 % with <5 % of added grated PUR. Furthermore, the flammable nature of PUR and its other drawbacks can be controlled by permanent embedding in the noncombustible structure of geopolymer, making the envelope of sustainable buildings green and safer. Overall, including grated waste PUR in geopolymer represents a promising, easy, cost-effective recycling path with low energy consumption, where the composite cannot develop fire on a scale of pure PUR, even in the worst-case scenario, but only if the composite is designed in a way, that flammable materials cannot join flames during their combustion. This paper gives prospects to other flammable waste materials to be safely used in the circular economy, and to porous materials to shape properties of the composite by their intrinsic and/or extrinsic properties.
Keywords: waste polyurethane foam, polymeric flame retardants, alkali activated material, metakaolin, microwave irradiation, thermal-fire behaviour, mechanical strength
Published in DiRROS: 01.03.2024; Views: 493; Downloads: 604
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812. Foundry wastes as a potential precursor in alkali activation technologyBarbara Horvat, Alenka Sešek Pavlin, Vilma Ducman, 2020, published scientific conference contribution Abstract: In this study the amount of amorphous phase of elements useful in alkali activation of waste materials produced by the foundry industry was determined. Waste foundry sands, foundry flue gas and waste casting cores were alkali activated, and waste green ceramics and bottom ash were added to one of the foundry sand samples to shorten the time for producing measurable compressive strength from 1.5 years to 1 week.
Keywords: alkali activated materials, foundry wastes, compressive strength, upcycling, circular ecnomy
Published in DiRROS: 01.03.2024; Views: 213; Downloads: 215
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813. B-IMPACT project : eco-friendly and non-hazardous coatings for the protection of outdoor bronzesGiulia Masi, Maëlenn Aufray, A. Balbo, E. Bernardi, Maria Chiara Bignozzi, Cristina Chiavari, J. Esvan, Nina Gartner, V. Grassi, Claudie Josse, Tadeja Kosec, Carla Martini, Cecilia Monticelli, Luka Škrlep, W. Sperotto, Erika Švara Fabjan, E. Tedesco, F. Zanotto, Luc Robbiola, 2020, published scientific conference contribution Abstract: Application of protective coatings is the most widely used conservation treatment for outdoor bronzes. Eco-friendly and non-hazardous coatings are currently needed for conservation of outdoor bronze monuments. To fulfil this need, the M-ERA.NET European research project B-IMPACT (Bronze-IMproved non-hazardous PAtina CoaTings) aimed at assessing the protectiveness of innovative coatings for historical and modern bronze monuments exposed outdoors.
In this project, two bronze substrates (historical Cu-Sn-Zn-Pb and modern Cu-Si-Mn alloys) were artificially patinated, by acid rain solution using dropping test and by "liver of sulphur" procedure (K2S aqueous solution) to obtain black patina, respectively. Subsequently, the application of several newly developed protective coatings was carried out and their performance was investigated by preliminary electrochemical tests. In the following steps of the work, the assessment of the best-performing coatings was carried out and their performance was compared to Incralac, one of the most widely used protective coatings in conservation practice. A multi-analytical approach was adopted, considering artificial ageing (carried out in representative conditions, including exposure to rain runoff, stagnant rain and UV radiation) and metal release, as well as visual aspect (so as to include aesthetical impact among the coating selection parameters) and morphological and structural evolution of the coated surfaces due to simulated outdoor exposure. Lastly, also the health impact of selected coatings was assessed by occupational hazard tests. The removability and re-applicability of the best-performing coatings were also assessed. The best alternatives to the conventional Incralac exhibited were: (i) fluoroacrylate blended with methacryloxy-propyl-trimethoxy-silane (FA-MS) applied on patinated Cu-Sn-Zn-Pb bronze and (ii) 3-mercapto-propyl-trimethoxysilane (PropS-SH) applied on patinated Cu-Si-Mn bronze.
Keywords: bronze, patina, protective coatings, eco-friendly, corrosion, aging
Published in DiRROS: 01.03.2024; Views: 196; Downloads: 100
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814. The deformation of alkali-activated materials at different curing temperaturesMark Češnovar, Katja Traven, Vilma Ducman, 2020, published scientific conference contribution Abstract: Alkali activation is a chemical process whereby materials rich in aluminosilicate, which dissolves in basic media at room temperature, form binding phases by polycondensation. The alkali- activated materials (AAM) are a promising alternative to binding materials such as cement or other products in civil engineering (van Deventer et al., 2012). This study investigates the early age shrinkage behavior of Slovenian ladle and electric arc furnace slag - based alkali activated materials at different curing temperatures. The dimensions of specimens cured at room temperature and elevated temperatures up to 90 °C were measured over the first 7 hours (every 10 min). The results show that the most shrinkage occurred at the highest temperature, owing to the highest rate of evaporation of liquid content. Loss of mass follows from the drying shrinkage.
Keywords: alkali activated materials, shrinkage, compressive strength
Published in DiRROS: 01.03.2024; Views: 315; Downloads: 412
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815. Delavnica Smernice za gospodarjenje z gozdovi na hudourniških območjih v luči nedavnih ujm na Gozdarskem inštitutu SlovenijeUrša Vilhar, Andrej Breznikar, Andreja Gregorič, Gregor Danev, Boris Rantaša, Jaša Saražin, David Štefanič, Jože Papež, 2023, professional article Keywords: gospodarjenje z gozdovi, urejanje hudournikov
Published in DiRROS: 29.02.2024; Views: 302; Downloads: 73
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817. Kompoziti iz skorje: nova gozdarsko-lesarska vrednostna verigaSergej Medved, Grega Vilman, Urban Tajher, Mark Sever, Alan Antonović, 2023, original scientific article Abstract: Skorja je večopravilni (večfunkcijski) material, saj deluje kot zaščita (pred fizikalnimi in mehanskimi poškodbami, pa tudi pred biološko razgradnjo), omogoča transport vode in plinov, občasno pomaga pri fotosintezi in nudi podporo drevesu. Skorje je od 10 % do 20 % celotne mase drevesa, vendar je znaten delež ostane neizkoriščen. Da bi prikazali možnosti rabe skorje za izdelavo različnih kompozitov, smo izdelali in analizirali tri različne kompozite, in sicer lesno-plastični kompozit iz skorje in polietilena, trislojni ploščni kompozit iz skorje, zlepljene z melamin-urea-formaldehidnim lepilom, in enoslojni ploščni kompozit iz vlažnih iveri skorje, zlepljenih s taninskimi lepili.
Keywords: skorja, iveri, lesno plastični kompozit, iverna plošča
Published in DiRROS: 29.02.2024; Views: 348; Downloads: 68
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818. Uredba EUDR – odgovor EU na izzive krčitev in degradacije gozdovMatjaž Dovečar, Špela Ščap, 2023, professional article Abstract: Prispevek predstavlja ključne vidike nove evropske uredbe, imenovane EUDR, in analizira njene posledice za zunanjo trgovino Republike Slovenije. Uredba je bila sprejeta kot odgovor na vedno večje težave glede krčitev in degradacije svetovnih gozdov. EUDR uveljavlja pravila in sistem potrebne skrbnosti za sedem ključnih primarnih proizvodov, ki so odgovorni za največji delež krčitev in degradacije gozdov, in sicer za dajanje na trg v državah članicah Evropske unije (vključno z uvozom iz tretjih držav) ter za izvoz v tretje države. To pomeni široko razširitev v primerjavi z dosedanjo uredbo EUTR, ki je prav tako določala obveznosti gospodarskih subjektov, ki dajejo les in lesne proizvode prvič na trg Evropske unije. Uredba EUDR nalaga nove zadolžitve gospodarskim subjektom in trgovcem, vplivala pa bo tudi na pristojne organe in carinske službe. Zaradi predvidevanja mogočih vplivov začetka izvajanja uredbe se prispevek osredotoča tudi na dve, za Slovenijo ključni kategoriji, in sicer lesni proizvodi in guma, ter predstavlja značilnosti zunanjetrgovinske menjave Slovenije z državami članicami in nečlanicami EU.
Keywords: uredba EUDR, krčenje gozdov, sistem potrebne skrbnosti, zunanja trgovina, tveganje
Published in DiRROS: 29.02.2024; Views: 360; Downloads: 109
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