1. Pitna voda v Mestni občini Ljubljana : pot od vodnega vira do kozarcaTadeja Kosec, Nina Gartner, Brigita Jamnik, Viviana Golja, Alenka Labovič, Lucija Smojver, Sabina Dolenec, Aljoša Šajna, Monika Novak Babič, Nina Gunde-Cimerman, Tinkara Kopar, 2019, professional monograph Keywords: centralni vodovodni sistem Ljubljana (CVS), pitna voda, materiali v stiku s pitno vodo, vzdrževanje sistemov, preskušanje, kovinski materiali, organski materiali, cementni materiali, mikrobiološki vpliv, certificiranje proizvodov, vodno gospodarstvo, oskrba z vodo
Published in DiRROS: 08.03.2024; Views: 141; Downloads: 64
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2. 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: 148; Downloads: 74
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3. Electrochemical corrosion tests on steel in alkali-activated materialsNina Gartner, Miha Hren, Tadeja Kosec, Andraž Legat, 2021, published scientific conference contribution Abstract: One of the potential alternatives to Ordinary Portland Cement (OPC) are Alkali-Activated Materials (AAMs). The service life of reinforced concrete structures greatly depends on the corrosion resistance of embedded steel reinforcement. Due to the wide range of AAMs and their diverse properties, corrosion processes of steel in these materials are relatively unknown. Corrosion monitoring methods or their interpretations in certain cases cannot be directly transferred from the ones for OPC materials. The chemical compositions of pore solution in different AAMs influence the results of electrochemical measurements and their interpretations. Within this research, three different alkali-activated mortar mixes were prepared, based on fly ash, slag or metakaolin. Pore solutions were extracted from each mortar andchemical analysis was acquired. Different electrochemical corrosion measurements were performed on steel submerged to synthetic pore solutions. In parallel, ordinary carbon steel reinforcing bar was installed in the same types of alkali-activated mortar mixes. Specimens were exposed to wet/dry cycles with saline solution and periodic measurements of electrochemical impedance spectroscopy (EIS) were performed. Measured parameters in both systems were analysedand compared. It was concluded that electrochemical measurements in pore solutions can provide basic overview on corrosion behaviour in different AAMs environments. Periodic EIS measurements enabled monitoring of corrosion initiation and propagation on steel reinforcement in AAMs, although the information on the corrosion type is missing. Interpretation of results depends on visual analysis of corrosion damages after the end of exposure, providing information on corrosion type and intensity. The continuation of research on corrosion monitoring techniques will be performed by using Electrical Resistance (ER) sensors and Coupled Multi-Electrode Array (CMEA) sensors.
Keywords: corrosion, alkali-activated mortars, pore solution extraction, electrochemical corrosion techniques, visual analysis
Published in DiRROS: 22.01.2024; Views: 221; Downloads: 116
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4. The corrosion properties of steel in pore solutions obtained from alkali‐activated mortarsNina Gartner, Tadeja Kosec, Stéphane Poyet, Andraž Legat, 2023, original scientific article Abstract: Alkali‐activated materials (AAMs) are considered a promising alternative to materials made from ordinary Portland cement (OPC). Other than considering the durability of the material itself, the use of AAMs for reinforced concrete elements also raises the question of steel corrosion processes in these materials, which are still relatively unknown. Three different alkali‐activated mortars were prepared for this study, based on either fly ash, slag, or metakaolin. Pore solutions were then extracted from each mortar and chemically analyzed. Electrochemical techniques were used to study the corrosion of steel in synthetic pore solutions containing varying concentrations of chlorides. In parallel, the same corrosion tests were performed in a generic pore solution representing OPC mortar. It was shown that the chemical composition differed in each pore solution tested, thus affecting the corrosion properties of the steel. The addition of chloride also had a varying effect on the corrosion properties of the steel in each type of pore solution tested. This study provided a basic overview of the corrosion behavior and mechanisms of the various AAM environments in comparison to that of OPC.
Keywords: alkali-aktivated materials, corrosion, electrochemical corrosion techniques, extracted pore solution
Published in DiRROS: 20.11.2023; Views: 268; Downloads: 48
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5. Monitoring the galvanic corrosion of copper–steel coupling in bentonite slurry during the early oxic phase using coupled multielectrode arraysTadeja Kosec, Miha Hren, Klara Prijatelj, Bojan Zajec, Nina Gartner, Andraž Legat, 2023, original scientific article Abstract: In the case of a two-part container for spent nuclear fuel, consisting of an iron-based inner structure with a copper coating, the potential perforation of copper through minor damage may result in intensive galvanic corrosion between copper and steel. The present work focuses on the corrosion of steel galvanically coupled to copper and exposed to a slightly saline environment under oxic conditions. The electrochemical processes on individual electrodes were monitored by coupled multielectrode arrays (CMEAs). The CMEAs were either in contact with groundwater saturated with bentonite or immersed in groundwater only. Very high galvanic corrosion currents were detected between carbon steel and pure copper in the early oxic phase. Additionally, the use of CMEAs further made it possible to monitor the distribution of cathodic currents around the steel electrode, which behaved anodically. Various microscopy and spectroscopy techniques were applied to identify the modes of corrosion and the type of corrosion products present at the end of the period of exposure.
Keywords: copper, steel, bentonite, Aspö groundwater, coupled multi electrode array, electrochemical properties, Raman analysis, corrosion
Published in DiRROS: 16.11.2023; Views: 403; Downloads: 68
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6. Monitoring the corrosion of steel in concrete exposed to a marine environmentNina Gartner, Tadeja Kosec, Andraž Legat, 2020, original scientific article Abstract: Reinforced concrete structures require continuous monitoring and maintenance to prevent corrosion of the carbon steel reinforcement. In this work, concrete columns with carbon and stainless steel reinforcements were exposed to a real marine environment. In order to monitor the corrosion processes, two types of corrosion probes were embedded in these columns at different height levels. The results from the monitoring of the probes were compared to the actual corrosion damage in the different exposure zones. Electrical resistance (ER) probes and coupled multi-electrodes (CMEs) were shown to be promising methods for long-term corrosion monitoring in concrete. Correlations between the different exposure zones and the corrosion processes of the steel in the concrete were found. Macrocell corrosion properties and the distribution of the separated anodic/cathodic places on the steel in chloride-contaminated concrete were addressed as two of the key issues for understanding the corrosion mechanisms in such environments. The specific advantages and limitations of the tested measuring techniques for long-term corrosion monitoring were also indicated. The results of the measurements and the corrosion damage evaluation clearly confirmed that the tested stainless steels (AISI 304 and AISI 304L) in a chloride-contaminated environment behave significantly better than ordinary carbon steel, with corrosion rates from 110% to 9500% lower in the most severe (tidal) exposure conditions.
Keywords: corrosion in concrete, steel reinforcement, long-term exposure, field exposure, electrical resistance (ER) probes, coupled multi-electrodes
Published in DiRROS: 21.08.2023; Views: 282; Downloads: 167
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7. Characterizing steel corrosion in different alkali-activated mortarsNina Gartner, Miha Hren, Tadeja Kosec, Andraž Legat, 2021, original scientific article Abstract: Alkali-activated materials (AAMs) present a promising potential alternative to ordinary Portland cement (OPC). The service life of reinforced concrete structures depends greatly on the corrosion resistance of the steel used for reinforcement. Due to the wide range and diverse properties of AAMs, the corrosion processes of steel in these materials is still relatively unknown. Three different alkali-activated mortar mixes, based on fly ash, slag, or metakaolin, were prepared for this research. An ordinary carbon-steel reinforcing bar was installed in each of the mortar mixes. In order to study the corrosion properties of steel in the selected mortars, the specimens were exposed to a saline solution in wet/dry cycles for 17 weeks, and periodic electrochemical impedance spectroscopy (EIS) measurements were performed. The propagation of corrosion damage on the embedded steel bars was followed using X-ray computed microtomography (XCT). Periodic EIS measurements of the AAMs showed different impedance response in individual AAMs. Moreover, these impedance responses also changed over the time of exposure. Interpretation of the results was based on visual and numerical analysis of the corrosion damages obtained by XCT, which confirmed corrosion damage of varying type and extent on steel bars embedded in the tested AAMs.
Keywords: corrosion, alkali-activated mortars, steel reinforcement, electrochemical impedance spectroscopy, X-ray computed microtomography, visual analysis
Published in DiRROS: 05.07.2023; Views: 386; Downloads: 180
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8. Application of electrochemical methods for studying steel corrosion in alkali-activated materialsShishir Mundra, Gabriel Samson, Giulia Masi, Rebecca Achenbach, David M. Bastidas, Susana Bernal, Maria Chiara Bignozzi, Maria Criado, Martin Cyr, Nina Gartner, Stefanie von Greve‐Dierfeld, Andraž Legat, Nikoonasab Ali, John L. Provis, Michael Raupach, Gregor J. G. Gluth, 2023, original scientific article Abstract: Alkali‐activated materials (AAMs) are binders that can complement and partially substitute the current use of conventional cement. However, the present knowledge about how AAMs protect steel reinforcement in concrete elements is incomplete, and uncertainties exist regarding the application of electrochemical methods to investigate this issue. The present review by EFC WP11‐Task Force ‘Corrosion of steel in alkali‐activated materials’ demonstrates that important differences exist between AAMs and Portland cement, and between different classes of AAMs, which are mainly caused by differing pore solution compositions, and which affect the outcomes of electrochemical measurements. The high sulfide concentrations in blast furnace slag‐based AAMs lead to distinct anodic polarisation curves, unusually low open circuit potentials, and low polarisation resistances, which might be incorrectly interpreted as indicating active corrosion of steel reinforcement. No systematic study of the influence of the steel–concrete interface on the susceptibility of steel to corrosion in AAMs is available. Less common electrochemical methods present an opportunity for future progress in the field.
Keywords: alkali-aktivated materials, alkali‐activated materials, anodic/cathodic polarisation, concrete, linear polarisation resistance, open circuit potential, reinforcement corrosion, resistivity
Published in DiRROS: 29.05.2023; Views: 312; Downloads: 136
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