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- Beitrag zu einem Tagungsband (18) (entfernen)
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- Concrete (4)
- Corrosion (4)
- Alkali-activated materials (3)
- Cathodic protection (2)
- Einflussgrößen (2)
- ICCP (2)
- Leaching (2)
- Steel corrosion (2)
- Steel reinforcement (2)
- Betonstahl (1)
- Bridge management (1)
- Carbonation (1)
- Chloride (1)
- Chloride Induced Corrosion (1)
- Chromate (1)
- Coating (1)
- Concrete parameters (1)
- Cunductive (1)
- Embedded Sensors (1)
- Fehlerquellen (1)
- Galvanized construction elements (1)
- Galvanized rebar (1)
- Geopolymers (1)
- Hydrogen evolution (1)
- Hydrogen-induced stress corrosion cracking (1)
- Inspection (1)
- Integrated Monitoring System (1)
- Kathodische Polarisation (1)
- Korrosion (1)
- Maintenance (1)
- Messraster (1)
- Nachweisgrenzen (1)
- Pitting corrosion (1)
- Praktische Bedeutung (1)
- Prestressed concrete (1)
- Prestressing steel (1)
- Prüfprotokoll (1)
- Rebar (1)
- Reinforcement (1)
- Reinforcement corrosion (1)
- Self-corrosion (1)
- Sensors (1)
- Spannbeton (1)
- Spannstahl (1)
- Verfahrensbeschreibung (1)
- Verzinkt (1)
- Verzinkte Einbauteile (1)
- Wasserstoffinduzierte Spannungsrisskorrosion (1)
- X-ray tomography (1)
- reinforcement (1)
Organisationseinheit der BAM
Investigations of corrosion on small cathodes in reinforced concrete - observations and suggestions
(2009)
Corrosion of steel reinforcement in concrete exposed to chloride containing environments is a serious
problem in civil engineering practice. The standards and guidelines contain only minimum
requirements regarding concrete quality and concrete cover. In very critical cases, for example the
ingress of chlorides, the application of different coatings is currently the only possibility to protect the
reinforced concrete structures. In this case the modelling of reinforcement corrosion would be more
practical. One sub-project of a DFG-research project (FOR 537) is currently performed at the Federal
Institute for Materials Research and Testing (BAM). Aim of the sub-project is the description of
corrosion propagation and the characterization of the corrosion on specimens with small cathodes by
electrochemical parameters. The electrochemical parameters are determined by suitable
electrochemical measurements, considering concrete parameters as well as different environmental
conditions.
Use of Embeddable Sensors in an Integrated Monitoring System for Reinforced Concrete Structures
(2003)
Corrosion behavior of galvanized reinforcement in chloride containing mortar and carbonated mortar
(2018)
Korrosionseigenschaften von feuerverzinktem Betonstahl unterscheiden sich grundlegend von herkömmlichen Betonstahl. In diesem Vortrag sind Beispiele für das Korrosionsverhalten in chloridhaltigen und carbonatisierten Mörteln dargestellt
Steel in concrete is protected by the alkaline pore water environment and the resulting formation of a protective passive layer against corrosion. Adverse environmental conditions due to carbonation or chloride ingress can destroy the passive layer on the steel surface. Corrosion processes starting in those areas lead to uniform corrosion or local corrosion like pitting corrosion. In comparison to uniform corrosion pitting corrosion is a form of increased local corrosion and thus leads to a progressive reduction in cross-section of the reinforcing steel. The corrosion products are first absorbed by the pores of the concrete matrix, without causing visible external changes at the concrete surface.
Carbon-based conductive coatings are complex composites, consisting of an organic or inorganic binder and conductive carbon components, for application as anodes in impressed current cathodic protection systems of reinforced concrete structures. The electrochemical properties of three coatings at different humidity and in saturated calcium hydroxide solution were studied by electrochemical methods, such as electrochemical impedance measurement, measuring of open circuit potential over time and galvanostatic polarization.
Carbon‐based conductive coatings are complex composites, consisting of an organic or inorganic binder and conductive carbon components, for application as anodes in impressed current cathodic protection systems of reinforced concrete structures. The electrochemical properties of three coatings at different humidity and in saturated calcium hydroxide solution were studied by electrochemical methods, such as electrochemical impedance measurement, measuring of open circuit potential over time and galvanostatic polarization. The dissolved organic and inorganic carbons in electrolyte solution were quantified by using a photometric method. The structures of the coatings were investigated before and after the electrochemical tests by microscopy and scanning electron microscope/EDX analysis. The results of the electrochemical impedance measurements show that the tested coatings all have a relatively low resistance, which is between 100 and 200V. The binder and the surface porosity influence the degradation behavior of those coatings. Especially the organic binder reacts with the strong alkaline medium under dissolving of organic carbon.
Alkali-activated fly ash mortars were studied with regard to durability-relevant transport coefficients and the electrochemical behaviour of embedded carbon steel bars on exposure of the mortars to leaching, carbonation and chloride penetration environments. The transport coefficients differed considerably between different formulations, being lowest for a mortar with BFS addition, but still acceptable for one of the purely fly ash-based mortars. Leaching over a period of ~300 days in de-ionized water did not lead to observable corrosion of the embedded steel, as shown by the electrochemical data and visual inspection of the steel. Exposure to 100 % CO2 atmosphere caused steel depassivation within approx. two weeks; in addition, indications of a deterioration of the mortar were observed. The results are discussed in the context of the different reaction products expected in high- and low-Ca alkali-activated binders, and the alterations caused by leaching and carbonation.