Influence of alternative binder systems on the corrosion behavior of the steel reinforcement - Part 2
Final Report Abstract
With the aim of reducing the environmental impact of cement production, various approaches are being pursued worldwide to develop new types of binders as alternatives to cements containing high amounts of Portland cement clinker. The properties of these alternative binders differ in various aspects from typical cement types, which can influence the expected durability of reinforced concrete components produced with these new binder types. Focusing on the effect of reinforcement passivation, nine different binders were investigated with regard to their potential applications and limitations in reinforced concrete in this project. This not only enabled a comprehensive characterization of the corrosion-relevant properties but also an evaluation of the standardized testing and assessment methods with regard to their suitability for the various new binder types. The individual approaches for producing alternative binders are at different stages on their way from research to practical application in reinforced concrete. Therefore, these investigations contribute to the state of knowledge at different starting points. For the formulations where the use in reinforced concrete has so far only been the subject of research, the first experimental results regarding their influence on the passivation behavior of the embedded reinforcing steel were obtained in this project. Corrosion can be initiated due to carbonation or chloride ingress. The duration until the onset of corrosion is therefore a decisive factor when evaluating the performance of a binder respectively concrete. Therefore, the suitability of standardized testing methods to quantify the duration of the initiation phase of corrosion in the reinforcement was assessed, and it was found that indicator-based methods do not reliably deliver results for all the investigated binder types. This is due to the influence of the pore solution composition on the chemical reaction of commonly used indicator solutions. As a promising alternative to indicator-based methods, the evaluation of the quality of mortars and concretes using electrical methods was proposed. The formation factor, which is calculated by dividing the specific electrical total resistance of the mortar or concrete by the specific electrical resistance of the pore solution, is highlighted as a universally suitable parameter to classify the permeability of the pore structure for corrosion-promoting substances and the influence of the pore structure on other transport-related processes. Based on the results of the investigations and the experience with the different binder types, recommendations for their testing, application in reinforced concrete, and further research needs were derived.
Publications
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Dauerhaftigkeitseigenschaften von alternativen Bindemitteln. Beton- und Stahlbetonbau, 116(10), 775-785.
Achenbach, Rebecca; Kraft, Bettina; Ludwig, Horst‐Michael & Raupach, Michael
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Hydration and Carbonation of Alternative Binders. Corrosion and Materials Degradation, 3(1), 19-52.
Kraft, Bettina; Achenbach, Rebecca; Ludwig, Horst-Michael & Raupach, Michael
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Influence of alternative binders on the passivation of steel in mortar. 6th International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2022), 03. – 05. 10.2022, Kapstadt, Südafrika
Achenbach, R. & Raupach, M.
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Applicability of the Formation Factor for Different Alternative Binder Types Investigated on Mortars. Corrosion, 79(7), 709-718.
Achenbach, Rebecca & Raupach, Michael
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Carbonation behaviour of concretes with alternative binders at different CO2 concentrations. ce/papers, 6(6), 1334-1341.
Kraft, Bettina; Müller, Matthias; Achenbach, Rebecca; Ludwig, Horst‐Michael & Raupach, Michael
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Comparative investigation on the influence of metakaolin, metaillite and steel slag as SCMs in mortar on the corrosion behavior of embedded steel. Koroze a ochrana materialu, 67(1), 21-32.
Achenbach, R. & Raupach, M.
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Comparative study on the electric resistance of mortars made of low carbon binders. Materials Today: Proceedings.
Achenbach, R.; Raupach, M.; Kraft, B.I.E. & Ludwig, H.-M.
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Eignung des RCM‐Versuchs zur Bestimmung des Chloridmigrationskoeffizienten in Mörteln aus alternativen Bindemitteln. ce/papers, 6(6), 1237-1245.
Achenbach, Rebecca; Kraft, Bettina I. E.; Raupach, Michael & Ludwig, Horst‐Michael
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Influence of CO2 Concentration During Accelerated Carbonation Tests with Alternative Binders. NanoWorld Journal, 9.
Kraft, B.I.E.; Müller, M.; Achenbach, R.; Ludwig, H.-M. & Raupach, M.
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Untersuchungen zum Einfluss von neuartigen Bindemitteln auf die Dauerhaftigkeit der Stahlbewehrung. Beiträge zur 10. DAfStb-Jahrestagung mit 62. Forschungskolloquium. - 26./27. September 2023 RWTH Aachen University; RWTH Aachen University, 2023; pp 239–248
Achenbach, R.; Raupach, M.; Kraft, B.I.E. & Ludwig, H.-M.
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Zur Anwendbarkeit des Formationsfaktors als Gefügekennwert für Mörtel aus verschiedenen alternativen Bindemittelsystemen. ce/papers, 6(6), 1324-1333.
Raupach, Michael; Achenbach, Rebecca; Ludwig, Horst‐Michael & Kraft, Bettina I. E.
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Corrosion protection of steel reinforcement by alternative binder types. RWTH Aachen University, Dissertation
Achenbach, R.
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Passivation of Steel Reinforcement in Low Carbon Concrete. Buildings, 14(4), 895.
Achenbach, Rebecca & Raupach, Michael
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Suitability of rapid chloride migration tests for determining the migration coefficient in mortars made from different novel binder types. Materials and Corrosion, 75(9), 1173-1184.
Achenbach, Rebecca & Raupach, Michael
