21. 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, izvirni znanstveni članek Povzetek: 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.
Ključne besede: alkali-aktivated materials, alkali‐activated materials, anodic/cathodic polarisation, concrete, linear polarisation resistance, open circuit potential, reinforcement corrosion, resistivity
Objavljeno v DiRROS: 29.05.2023; Ogledov: 308; Prenosov: 134
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22. Antibacterial properties and cytotoxicity of 100% waste derived alkali activated materials : slags and stone wool-based bindersCaterina Sgarlata, Giovanni Dal Poggetto, Federica Piccolo, Michelina Catauro, Katja Traven, Mark Češnovar, Hoang Nguyen, Juho Yliniemi, Luisa Barbieri, Vilma Ducman, Isabella Lancellotti, Cristina Leonelli, 2021, izvirni znanstveni članek Povzetek: In this study we compare the leaching behavior and the antibacterial and cytotoxic properties of 100% slag or stone wool derived alkali activated materials. The antibacterial activity was measured as the inhibiting capacity against two Gram- negative bacterial strains, Escherichia coli and Pseudomonas aeruginosa and one Gram-positive bacterial strain: Enterococcus faecalis. The cytotoxicity properties were tested on mouse embryonic fibroblast NIH-3T3 cell-line. It was proved that the high quality of the 3D aluminosilicate network of the consolidated materials obtained from powders of CaO or MgO-rich slags or stone wool, opportunely activated with NaO and/or Na-silicate, was capable of stabilizing heavy metal cations. The concentrations of leachate heavy cations were lower than the European law limit when tested in water. The effect of additives in the composites, basal fibers or nanocellulose, did not reduce the chemical stability and slightly influenced the compressive strength. Weight loss in water increased by 20% with basalt fibers addition, while it remained almost constant when nanocellulose was added. All the consolidated materials, cement-like in appearance, exhibited limited antibacterial properties (viability from 50 to 80% depending on the bacterial colony and the amount of sample) and absence of cytotoxicity, envisaging good acceptance from part of the final consumer and zero ecological impact. CaO-rich formulations can replace ordinary Portland cement (showing bacterial viability at 100%) with a certain capability for preventing the reproduction of the E. coli and S. aureus bacteria with health and environmental protection results.
Ključne besede: antibacterial properties, cytotoxicity, alkali-activated materials, slag, stone wool, waste utilization, social acceptance
Objavljeno v DiRROS: 22.05.2023; Ogledov: 337; Prenosov: 187
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