TY - JOUR A1 - Grengg, C. A1 - Koraimann, G. A1 - Ukrainczyk, N. A1 - Rudic, O. A1 - Luschnig, S. A1 - Gluth, Gregor A1 - Radtke, Martin A1 - Dietzel, M. A1 - Mittermayr, F. T1 - Cu- and Zn-doped alkali activated mortar – Properties and durability in (bio)chemically aggressive wastewater environments N2 - Metakaolin-based alkali activated mortars (AAM) - with and without CuSO4·5H2O and ZnO addition (mass ratio Mn+/solid binder 0.08% to 1.7%) - were casted and exposed within an extensive long-term field campaign over the period of 20 months to a sewer basin, strongly affected by biogenic acid corrosion. (Un-)exposed AAM were tested regarding their physicochemical and microstructural properties, bioreceptivity and overall durability. Metal addition led to a retarding effect during alkali-activation reaction, as well as to an increase in open porosity of up to 3.0% and corresponding lower compressive strength of up to 10.9%. Reduced microbial colonization and diversity were observed on AAM with Cu, while Zn addition led to increased biodiversity. We propose that the observed higher durability of Cu-doped AAM is due to antibacterial effects and associated reduction of biogenic acid production, superseding overall negative effects of metal-dosage on physical material properties. Observed lower durability of Zn-doped AAM was related to combined negative physicochemical and microbial effects. KW - Microbially induced corrosion KW - Alkali-activated materials KW - Biogenic acid corrosion KW - Biogene Schwefelsäurekorrosion KW - MIC PY - 2021 DO - https://doi.org/10.1016/j.cemconres.2021.106541 SN - 0008-8846 VL - 149 SP - 1 EP - 15 PB - Elsevier CY - Oxford AN - OPUS4-53070 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grengg, C. A1 - Gluth, Gregor A1 - Mittermayr, F. A1 - Ukrainczyk, N. A1 - Bertmer, M. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Leis, A. A1 - Dietzel, M. T1 - Deterioration mechanism of alkali-activated materials in sulfuric acid and the influence of Cu: A micro-to-nano structural, elemental and stable isotopic multi-proxy study N2 - In this study, a multi-proxy approach combining 29Si, 27Al and 1H MAS-NMR, FEG-EPMA, XANES at the Cu K-edge and XRD analytics with hydrochemical tools such as ICP-OES analyses, oxygen-isotope signatures, and thermodynamic modelling was applied to K-silicate-activated metakaolin specimens - with and without CuSO4·5H2O addition - exposed to sulfuric acid at pH = 2 for 35 days. The results revealed a multistage deterioration mechanism governed by (i) acid diffusion, (ii) leaching of K-A-S-H, (iii) microstructural damage related to precipitation of expansive (K,Ca,Al)-sulfate-hydrate phases (iv) complete dissolution of the K-A-S-H framework, (v) and formation of silica gel in the outermost corroded regions. Copper ions were mainly located in layered spertiniite-chrysocolla-like phases in the as-cured materials. The results demonstrate an overall negative effect of Cu addition on chemical material durability, implying that the reported higher durability of Cu-doped AAM in biocorrosion environments can be best explained by bacteriostatic effects. KW - Alkali-activated materials KW - Acid resistance KW - Microbially induced corrosion KW - MIC PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520567 DO - https://doi.org/10.1016/j.cemconres.2021.106373 SN - 0008-8846 VL - 142 SP - 1 EP - 15 PB - Elsevier CY - Oxford AN - OPUS4-52056 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Grengg, C. A1 - Gluth, Gregor A1 - Mittermayr, F. ED - Jiang, G. T1 - Alkali-activated materials for sewers N2 - This chapter aims to give a brief introduction into the field of alkali activated materials (AAM) and their physicochemical material behavior when exposed to sulfuric acid and in biochemically aggressive sewer environments. Additionally, the differences in material behavior within chemical (abiotic) and microbially induced acid environments are highlighted. Finally, existing data on overall performance of AAM, compared to conventional concrete-based building materials in sewer systems will be discussed. KW - Alkali-activated materials KW - Geopolymers KW - MIC KW - Sewage systems PY - 2023 SN - 978-3-031-29940-7 SN - 978-3-031-29941-4 DO - https://doi.org/10.1007/978-3-031-29941-4_11 SP - 233 EP - 247 PB - Springer CY - Cham AN - OPUS4-57424 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gluth, Gregor A1 - Grengg, C. A1 - Ukrainczyk, N. A1 - Mittermayr, F. A1 - Dietzel, M. T1 - Acid resistance of alkali-activated materials: Recent advances and research needs N2 - Cementitious materials are frequently applied in environments in which they are exposed to acid attack, e.g., in sewer systems, biogas plants, and agricultural/food-related industries. Alkali-activated materials (AAMs) have repeatedly been shown to exhibit a remarkably high resistance against attack by organic and inorganic acids and, thus, are promising candidates for the construction and the repair of acid-exposed structures. However, the reaction mechanisms and processes affecting the acid resistance of AAMs have just recently begun to be understood in more detail. The present contribution synthesises these advances and outlines potentially fruitful avenues of research. The interaction between AAMs and acids proceeds in a multistep process wherein different aspects of deterioration extend to different depths, complicating the overall determination of acid resistance. Partly due to this indistinct definition of the ‘depth of corrosion’, the effects of the composition of AAMs on their acid resistance cannot be unambiguously identified to date. Important parallels exist between the deterioration of low-Ca AAMs and the weathering/corrosion of minerals and glasses (dissolution-reprecipitation mechanism). Additional research requirements relate to the deterioration mechanism of high-Ca AAMs; how the character of the corroded layer influences the rate of deterioration; the effects of shrinkage and the bond between AAMs and substrates. KW - Alkali-activated materials KW - Acid attack KW - Acid resistance KW - Concrete repair KW - MIC PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-557376 DO - https://doi.org/10.21809/rilemtechlett.2022.157 SN - 2518-0231 VL - 7 SP - 58 EP - 67 PB - RILEM Publications SARL CY - Paris AN - OPUS4-55737 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gluth, Gregor ED - Wittke, W. T1 - Alkalisch aktivierter Beton (Geopolymer-Beton) N2 - Alkalisch aktivierte Bindemittel (AAB) sind Zemente, deren Erhärtung auf der alkalischen Anregung von reaktiven Aluminiumsilicaten beruht. AAB sind nach gegenwärtigem Stand die vielversprechendste Option, die mit der Herstellung und dem Einsatz von Zementen verbundenen CO2-Emissionen mittel- bis langfristig signifikant zu senken. Die Erhärtungsreaktionen und die Einflüsse auf die Mikrostruktur von AAB sind durch jahrzehntelange Forschung gut verstanden, und zahlreiche Beispiele belegen, dass AAB grundsätzlich als Betonbindemittel geeignet sind. Offene Fragen bestehen aber immer noch hinsichtlich der Dauerhaftigkeit von mit AAB hergestellten Betonen. Der vorliegende Beitrag gibt eine kurze Einführung in die Nomenklatur und die Geschichte von AAB. Die wichtigsten Reaktionen und Reaktionsprodukte, die zur Bildung der Mikrostruktur von AAB führen, werden beschrieben. Der Hauptteil des Beitrags diskutiert aktuelle Forschungsergebnisse und offene Fragen zur Dauerhaftigkeit von Betonen auf Basis von AAB. Wichtige Fortschritte auf diesem Gebiet konnten in den letzten Jahren insbesondere zum Einfluss von Sulfiden auf die Bewehrungskorrosion, zum Carbonatisierungswiderstand und zum Säurewiderstand erzielt werden. T2 - 10. Felsmechanik- und Tunnelbautag CY - Weinheim, Germany DA - 22.05.2025 KW - Alkali-activated materials KW - Carbonation KW - Reinforcement corrosion KW - MIC KW - Microbially induced corrosion PY - 2025 SN - 978-3-00-083562-9 SP - 73 EP - 84 PB - WBI GmbH CY - Weinheim AN - OPUS4-64266 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gluth, Gregor T1 - Microbially induced corrosion of cementitious materials in sewer systems N2 - Sewer networks (also called wastewater systems) include structures to collect and transport wastewater to disposal or treatment in dedicated facilities. These networks are essential infrastructures of our societies, and the size of these systems in terms of length as well as asset value is usually vast. Accordingly, the annual rehabilitation and replacement costs for sewer networks are very high in many countries. In addition, failures of wastewater systems can cause severe health and environmental problems, making the durability of these infrastructures an issue of crucial societal importance. A substantial fraction of the deterioration of sewers is caused by microbially influenced corrosion (MIC) of concrete structures in the networks, and, thus, understanding the causes of this process is crucial to be able to effectively direct resources for rehabilitation, replacement and construction of sewer systems. Because of the importance of the problem, it has been studied for many decades, and significant progress has been made during this time. In recent years, answers to several previously underexplored questions, for example regarding the validity of the different test methods to assess the resistance of cementitious materials against MIC and the suitability of new cementitious materials for sewer repair, have begun to emerge. The present contribution gives an overview over the processes involved in MIC of cementitious materials in sewers, and reviews recent findings concerning the resistance of cementitious materials against MIC. The data indicate that alkali-activated materials can exhibit exceptionally high resistance against MIC, while it is presently not fully understood which mix design parameters deter¬mine this resistance. Disagreement exists in the literature regarding the causes of the generally high resistance of calcium aluminate cements. Significant progress has been made in determining the deterioration rate of cementitious materials under strongly corroding conditions, but well-founded approaches to classify the severity of MIC attack in sewers seem not to be available at present. T2 - MICxUS 2025 – Symposium on Microbiologically Influenced Corrosion (MIC) in Industrial and Utility Systems CY - Nicosia, Cyprus DA - 21.01.2025 KW - MIC KW - Cement KW - Repair mortar KW - Sulfuric acid KW - Sewers PY - 2025 AN - OPUS4-62738 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bertron, A. A1 - Grengg, C. A1 - Peyre Lavigne, M. A1 - Wack, H. A1 - Gluth, Gregor A1 - Aboulela, A. A1 - Sonois, V. A1 - Mittermayr, F. T1 - Comparative evaluation of laboratory methods for performance assessment of cementitious materials in wastewater networks: Biological and chemical tests versus field exposure N2 - The biodeterioration of concrete elements in sewer systems and their repair is of significant economic and societal concern. However, the available test methods to assess the performance of cementitious materials under the relevant conditions are insufficiently validated. In the present study, two biological test methods and a standardised chemical test were applied to two sewer repair mortars and a reference mortar, and the performances of these materials were compared in a severely deteriorating sewer environment. In both biological tests, the induction period was considerably shorter than that of the field, and time-resolved recording of durability indicators enabled to determine deterioration rates in the steady-state regime, which compared reasonably well with each other and with the behaviour in the sewer environment. The chemical test does not allow to obtain a deterioration rate, and the observed relative performance differences of the mortars deviated from the results of the biological tests. KW - MIC KW - Biodeterioration KW - Sulfuric acid attack KW - Testing KW - Cementitious repair systems PY - 2025 DO - https://doi.org/10.1016/j.cemconres.2024.107741 SN - 0008-8846 SN - 1873-3948 VL - 188 SP - 1 EP - 18 PB - Elsevier Ltd. AN - OPUS4-61857 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -