TY - CONF A1 - Kühne, Hans-Carsten A1 - Hüsken, Götz A1 - Mundra, Shishir A1 - Sander, C. A1 - Obermann, S. T1 - Die Betondickglasfenster des Glockenturms am Eiermannbau der Kaiser-Wilhelm-Gedächtniskirche N2 - Die Kaiser-Wilhelm-Gedächtniskirche (KWG) gilt als eine der wichtigsten Sehenswürdigkeiten Berlins in der City West und als ein herausragendes Beispiel für die „Dalle de Verre“ Verglasungen in sakralen Gebäuden. Der vorliegende Beitrag widmet sich der Fassade und den Glasfenstern des neuen Glockenturms, wobei die beschriebenen Szenarien aufgrund der annähernd gleichen Bauweise der restlichen neuen Baukörper in weiten Teilen starke Analogien aufweisen und insofern übertragbar sind. T2 - Workshop Kulturguterhaltung - Vom Dampfkessel zu Nanomaterialien CY - Berlin, Germany DA - 17.11.2021 KW - Kaiser-Wilhelm-Gedächtniskirche KW - Betondickglasfenster KW - Instandsetzung KW - Elektrochemische Realkalisierung PY - 2021 VL - 3 SP - 125 EP - 140 PB - Druckerei G. Bohm CY - Berlin AN - OPUS4-57092 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mundra, Shishir A1 - Hüsken, Götz A1 - Kühne, Hans-Carsten ED - Sena-Cruz, J. ED - Correia, L. ED - Azenha, M. T1 - Electrochemical realkalisation of carbonated "Dalle de Verre" windows N2 - Concrete-glass windows or commonly referred to as “Dalle de Verre” windows are prevalent in historical monuments across Europe. “Dalle de Verre” windows were made by placing cut stained glasses, of various shapes and sizes, into a steel reinforced concrete frame. In addition to the steel reinforcement, a few steel wires run across the concrete elements to hold the glass windows into place. Much of these structures have been damaged due to carbonation of the thin concrete covers and consequent corrosion of the steel reinforcement; and exhibit several cracks due to the expansive nature of corrosion products formed at the steel–concrete interface. This study focussed on understanding the efficacy of electrochemical realkalisation in reinstating the passive state of the steel reinforcement embedded in such concrete glass windows. Simulant “Dalle de Verre” windows (representative of windows at Kaiser-Wilhelm Gedächtniskirche) were produced using different cements with a water/cement ratio of 0.6 and carbonated under accelerated conditions. Post carbonation, the concrete glass windows were electrochemically realkalised using a sacrificial anode. The influence of highly alkaline conditions due to electrochemical realkalisation on the glass-concrete interface has also been investigated. This study shows that the passive state of the steel reinforcement in “Dalle de Verre” windows, particularly at the Kaiser-Wilhelm Gedächtniskirche (memorial church) in Berlin, can be reinstated using the electrochemical realkalisation method. T2 - 3rd RILEM Spring Convention and Conference (RSCC 2020) CY - Online meeting DA - 10.03.2020 KW - Electrochemical realkalisation KW - Carbonation KW - Concrete-glass windows KW - Passivation KW - Dalle-de-verre PY - 2021 SN - 978-3-030-76465-4 DO - https://doi.org/10.1007/978-3-030-76465-4_15 SN - 2211-0844 VL - RILEM bookseries 34 SP - 163 EP - 171 PB - Springer CY - Cham AN - OPUS4-54299 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Angst, U.M. A1 - Geiker, M.R. A1 - Alonso, M.C. A1 - Polder, R. A1 - Isgor, O.B. A1 - Elsener, B. A1 - Wong, H. A1 - Michel, A. A1 - Hornbostel, K. A1 - Gehlen, C. A1 - François, R. A1 - Sanchez, M. A1 - Criado, M. A1 - Sørensen, H. A1 - Hansson, C. A1 - Pillai, R. A1 - Mundra, Shishir A1 - Gulikers, J. A1 - Raupach, M. A1 - Pacheco, J. A1 - Sagüés, A. T1 - The effect of the steel-concrete interface on chloride-induced corrosion initiation in concrete: a critical review by RILEM TC 262-SCI N2 - The steel–concrete interface (SCI) is known to influence corrosion of steel in concrete. However, due to the numerous factors affecting the SCI—including steel properties, concrete properties, execution, and exposure conditions—it remains unclear which factors have the most dominant impact on the susceptibility of reinforced concrete to corrosion. In this literature review, prepared by members of RILEM technical committee 262-SCI, an attempt is made to elucidate the effect of numerous SCI characteristics on chloride-induced corrosion initiation of steel in concrete. We use a method to quantify and normalize the effect of individual SCI characteristics based on different literature results, which allows comparing them in a comprehensive context. It is found that the different SCI characteristics have received highly unbalanced research attention. Parameters such as w/b ratio and cement type have been studied most extensively. Interestingly, however, literature consistently indicates that those parameters have merely a moderate effect on the corrosion susceptibility of steel in concrete. Considerably more pronounced effects were identified for (1) steel properties, including metallurgy, presence of mill scale or rust layers, and surface roughness, and (2) the moisture state. Unfortunately, however, these aspects have received comparatively little research attention. Due to their apparently strong influence, future corrosion studies as well as developments towards predicting corrosion initiation in concrete would benefit from considering those aspects. Particularly the working mechanisms related to the moisture conditions in microscopic and macroscopic voids at the SCI is complex and presents major opportunities for further research in corrosion of steel in concrete. KW - Steel-concrete interface KW - Interfacial transition zone KW - Durability KW - Corrosion KW - Inhomogeneity KW - Variability PY - 2019 DO - https://doi.org/10.1617/s11527-019-1387-0 VL - 52 IS - 4 SP - 88-1 EP - 88-25 PB - Springer Nature AN - OPUS4-48689 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mundra, Shishir A1 - Samson, G. A1 - Masi, G. A1 - Achenbach, R. A1 - Bastidas, D. M. A1 - Bernal, S. A. A1 - Bignozzi, M. C. A1 - Criado, M. A1 - Cyr, M. A1 - Gartner, N. A1 - von Greve-Dierfeld, S. A1 - Legat, A. A1 - Nikoonasab, Ali A1 - Provis, J. L. A1 - Raupach, M. A1 - Gluth, Gregor T1 - Stahlkorrosion in alkalisch aktivierten Bindemitteln und Betonen: Anwendung elektrochemischer Methoden N2 - Alkalisch aktivierte Bindemittel (AAB) und Betone können herkömmliche Zemente beziehungsweise Betone potentiell in vielen Anwendungen ersetzen und dadurch den CO2-Fußabdruck der Bauindustrie wesentlich verkleinern. Zur Untersuchung der Stahlkorrosion in bewehrten („armierten“) Betonbauteilen werden elektrochemische Methoden wie Messungen des Freien Korrosionspotentials, des Polarisationswiderstands oder von Stromdichte-Potential-Kurven eingesetzt. Diese Methoden und die etablierten Grenzwerte zur Detektion von Korrosion sind für die Anwendung bei herkömmlichen Zementen beziehungsweise Betonen entwickelt und erprobt worden. Neue Forschungsergebnisse demonstrieren, dass Unterschiede zwischen den Porenlösungszusammensetzungen von herkömmlichen Zementen und bestimmten AAB sowie anderen schlackehaltigen Zementen erhebliche Unterschiede bei den Ergebnissen der elektrochemischen Messungen bewirken und damit zur fehlerhaften Detektion von Stahlkorrosion führen können. Ursache hierfür sind vor allem reduzierte Schwefelspezies in den Porenlösungen von AAB und anderen schlackehaltigen Zementen. KW - Zement KW - Hüttensandmehl KW - Schlacke KW - Sulfid KW - Korrosion PY - 2023 UR - https://bit.ly/GIT-Gluth UR - https://analyticalscience.wiley.com/content/magazine-do/git-labor-fachzeitschrift-10-2023 SN - 0016-3538 VL - 67 IS - 10 SP - 28 EP - 31 PB - Wiley-VCH AN - OPUS4-58573 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gluth, Gregor A1 - Mundra, Shishir A1 - Henning, Ricky T1 - Chloride binding by layered double hydroxides (LDH/AFm phases) and alkali-activated slag pastes: an experimental study by RILEM TC 283-CAM N2 - Chloride binding by the hydrate phases of cementitious materials influences the rate of chloride ingress into these materials and, thus, the time at which chloride reaches the steel reinforcement in concrete structures. Chloride binding isotherms of individual hydrate phases would be required to model chloride ingress but are only scarcely available and partly conflicting. The present study by RILEM TC 283-CAM ‘Chloride transport in alkali-activated materials’ significantly extends the available database and resolves some of the apparent contradictions by determining the chloride binding isotherms of layered double hydroxides (LDH), including AFm phases (monosulfate, strätlingite, hydrotalcite, and meixnerite), and of alkali-activated slags (AAS) produced with four different activators (Na2SiO3, Na2O·1.87SiO2, Na2CO3, and Na2SO4), in NaOH/NaCl solutions at various liquid/solid ratios. Selected solids after chloride binding were analysed by X-ray diffraction, and thermodynamic modelling was applied to simulate the phase changes occurring during chloride binding by the AFm phases. The results of the present study show that the chloride binding isotherms of LDH/AFm phases depend strongly on the liquid/solid ratio during the experiments. This is attributed to kinetic restrictions, which are, however, currently poorly understood. Chloride binding by AAS pastes is only moderately influenced by the employed activator. A steep increase of the chloride binding by AAS occurs at free chloride concentrations above approx. 1.0 M, which is possibly related to chloride binding by the C–(N–)A–S–H gel in the AAS. KW - Chloride binding KW - Sorption isotherm KW - Layered double hydroxide KW - AFm phase KW - Alkali-activated materials PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-599370 DO - https://doi.org/10.1617/s11527-024-02311-3 SN - 1359-5997 SN - 1871-6873 VL - 57 IS - 4 SP - 1 EP - 17 PB - Springer Nature AN - OPUS4-59937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mundra, Shishir A1 - Provis, J. L. T1 - Mechanisms of passivation and chloride-induced corrosion of mild steel in sulfide-containing alkaline solutions N2 - The pore fluid within many concretes is highly alkaline and rich in reduced sulfur species, but the influence of such alkaline-sulfide solutions on the surface film formed on steel reinforcement is poorly understood. This study investigates the critical role of HS− in defining mild steel passivation chemistry. The surface film formed on the steel in alkaline-sulfide solutions contains Fe(OH)2 and Fe–S complexes, and the critical chloride concentration to induce corrosion increases at high sulfide concentration. However, this behavior is dependent on the duration of exposure of the steel to the electrolyte, and the nature of the sulfidic surface layer. KW - Alkali-activated materials KW - Steel corrosion KW - Sulfide KW - Chloride PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-528861 DO - https://doi.org/10.1007/s10853-021-06237-x VL - 56 IS - 26 SP - 14783 EP - 14802 PB - Springer Nature AN - OPUS4-52886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -