TY - CONF A1 - Gluth, Gregor A1 - Ke, X. A1 - Vollpracht, A. A1 - Bernal, S. A. A1 - Cizer, Ö. A1 - Cyr, M. A1 - Dombrowski-Daube, K. A1 - Geddes, D. A1 - Grengg, C. A1 - Le Galliard, C. A1 - Nedeljkovic, M. A1 - Provis, J. L. A1 - Shi, Z. A1 - Valentini, L. A1 - Walkley, B. ED - Escalante-Garcia, J. I. ED - Castro Borges, P. ED - Duran-Herrera, A. T1 - RILEM TC 281-CCC Working Group 6: Carbonation of alkali activated concrete—preliminary results of a literature survey and data analysis N2 - The current understanding of the carbonation of alkali-activated concretes is ham-pered inter alia by the wide range of binder chemistries used. To overcome some of the limitations of individual studies and to identify general correlations between their mix design parameters and carbonation resistance, the RILEM TC 281-CCC working group 6 compiled carbonation data for alkali-activated concretes and mortars from the literature. For comparison purposes, data for blended Portland cement-based concretes with a high percentage of SCMs (≥ 66 % of the binder) were also included in the database. A preliminary analysis of the database indicates that w/CaO ratio and w/b ratio exert an influence on the carbonation resistance of alkali-activated concretes but, contrary to what has been reported for concretes based on (blended) Portland cements, these are not good indicators of their carbonation resistance when considered individually. A better indicator of the carbonation resistance of alkali-activated concretes under conditions approxi-mating natural carbonation appears to be their w/(CaO + Na2O + K2O) ratio. Furthermore, the analysis points to significant shortcomings of tests at elevated CO2 concentrations for low-Ca alkali-activated concretes, indicating that even at a concentration of 1 % CO2, the outcomes may lead to inaccurate predictions of the carbonation coefficient under natural exposure conditions. T2 - 75th RILEM Annual Week CY - Mérida, Yucatán, Mexico DA - 30.08.2021 KW - Alkali-activated materials KW - Durability KW - Carbonation KW - Testing KW - Concrete PY - 2023 SN - 978-3-031-21734-0 SN - 978-3-031-21735-7 U6 - https://doi.org/10.1007/978-3-031-21735-7_72 SN - 2211-0852 SN - 2211-0844 VL - 40 SP - 667 EP - 676 PB - Springer CY - Cham AN - OPUS4-57157 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 - CONF A1 - Gluth, Gregor A1 - Ke, X. A1 - Vollpracht, A. A1 - Weiler, L. A1 - Bernal, S. A. A1 - Cyr, M. A1 - Dombrowski-Daube, K. A1 - Geddes, D. A1 - Grengg, C. A1 - Le Galliard, C. A1 - Nedeljkovic, M. A1 - Provis, J. L. A1 - Valentini, L. A1 - Walkley, B. ED - Jędrzejewska, A. ED - Kanavaris, F. ED - Azenha, M. ED - Benboudjema, F. ED - Schlicke, D. T1 - Carbonation of alkali-activated concretes: effects of compositional parameters and carbonation conditions N2 - The current ability to predict the carbonation resistance of alkali-activated materials (AAMs) is incomplete, partly because of widely varying AAM chemistries and variable testing conditions. To identify general correlations between mix design parameters and the carbonation rate of AAMs, RILEM TC 281-CCC Working Group 6 compiled and analysed carbonation data for alkali-activated concretes and mortars from the literature. For comparison purposes, data for blended Portland cement-based concretes with a high percentage of SCMs (≥66% of the binder) were also included in the database. The results show that the water/CaO ratio is not a reliable indicator of the carbonation rate of AAMs. A better indicator of the carbonation rate of AAMs under conditions approximating natural carbonation is their water/(CaO + MgOeq + Na2Oeq + K2Oeq) ratio, where the index ‘eq’ indicates an equivalent amount based on molar masses. This finding can be explained by the CO2 binding capacity of alkaline-earth and alkali metal ions; the obtained correlation also indicates an influence of the space-filling capability of the binding phases of AAMs, as for conventional cements. However, this ratio can serve only as an approximate indicator of carbonation resistance, as other parameters also affect the carbonation resistance of alkali-activated concretes. In addition, the analysis of the dataset revealed peculiarities of accelerated tests using elevated CO2 concentrations for low-Ca AAMs, indicating that even at the relatively modest concentration of 1% CO2, accelerated testing may lead to inaccurate predictions of their carbonation resistance under natural exposure conditions. T2 - International RILEM Conference on Synergising Expertise towards Sustainability and Robustness of Cement-based Materials and Concrete Structures: SynerCrete 2023 CY - Adamantas, Greece DA - 14.06.2023 KW - Carbonation KW - Alkali-activated materials KW - Mix design PY - 2023 U6 - https://doi.org/10.1007/978-3-031-33187-9_94 VL - 2 SP - 1029 EP - 1037 PB - Springer CY - Cham AN - OPUS4-57699 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mundra, Shishir A1 - Prentice, D. P. A1 - Bernal, S. A. A1 - Provis, J. L. T1 - Modelling chloride transport in alkali-activated slags N2 - The service-life of steel-reinforced concrete structures is primarily determined by the ability of the concrete cover to resist chloride ingress. With limited literature available on the ingress of chloride into alkali-activated slags (AAS) under service conditions, it is critical that this is described by appropriate models. This paper describes an interactive software framework to relate chloride ingress into AAS with the chemistry of the concrete cover, by considering the chloride binding capacity and porosity of the binder as a function of time, based on thermodynamic calculations of the phase assemblage as a function of slag and activator composition. This provides a major step towards developing the ability to predict the ingress of chlorides in alkali-activated concretes from a sound theoretical basis, which is essential in providing confidence in the durability of these materials in essential infrastructure applications. KW - Thermodynamic calculations KW - Alkali activated cement KW - Durability KW - Diffusion KW - Chloride PY - 2020 U6 - https://doi.org/10.1016/j.cemconres.2020.106011 VL - 130 SP - 106011 PB - Elsevier Ltd. AN - OPUS4-50423 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -