TY - JOUR A1 - Ebell, Gino A1 - Burkert, Andreas A1 - Lehmann, Jens A1 - Mietz, Jürgen T1 - Electrochemical investigations on the corrosion behaviour of galvanized reinforcing steels in concrete with chromate-reduced cements JF - Materials and corrosion N2 - The reduction of the chromate contents in cements affects the electrochemical reactions of galvanized reinforcing steels in fresh concrete. By means of electrochemical measurements and bar pull-out tests the effect of chromates on the formation of protective coatings at the zinc and the bond behaviour have been investigated using chromate-containing and chromate-reduced cements. The results have shown that the bond zone was affected as a result of chromate reduction for cement types CEM I and CEM II. The disturbance to the bond zone should be considered as long-term in relation to the pore structure which is formed. The effects on the bond are largely compensated for as the concrete ages. The results of the related bond strength with displacement paths of 0.1 and 0.5?mm, respectively, are still within the range of expected figures for non-galvanized reinforcing steel despite the structural disturbance. Under practical aspects it is not necessary that the existing structural disturbance with respect to bond strength is taken into consideration. KW - Cement KW - Chromate KW - Concrete KW - Electrochemical measurements KW - Galvanized steel KW - Polarization KW - Pull-out tests KW - Reinforcing steel KW - Zinc PY - 2012 DO - https://doi.org/10.1002/maco.201106311 SN - 0947-5117 SN - 1521-4176 VL - 63 IS - 9 SP - 791 EP - 802 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-26568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Ebell, Gino A1 - Achenbach, R. A1 - Angst, U. A1 - Dauberschmidt, C. A1 - Eichler, T. A1 - Hariri, K. A1 - Harnisch, J. A1 - Keßler, S. A1 - Kosalla, M. A1 - Mayer, T.F. A1 - Mietz, Jürgen A1 - Pruckner, F. A1 - Sodeikat, C. T1 - Specification B 12 - Corrosion monitoring in reinforced and prestressed concrete structures N2 - This specification describes how corrosion monitoring is used to check the condition of reinforced and prestressed concrete members. In this specification, the term "corrosion monitoring" covers all methods in which it is possible to continuously track corrosion-relevant variables in the area of stationary, built-in sensors. This specification does not cover other possible methods, such as potential field measurements, involving the use of mobile, portable sensors that are placed temporarily on the membersurface to take measurements. KW - Korrosion KW - Corrosion KW - Monitoring PY - 2021 SN - 978-3-947971-14-5 SP - 1 EP - 55 PB - DGZfP CY - Berlin AN - OPUS4-53092 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ebell, Gino A1 - Poltavtseva, M. A1 - Mietz, Jürgen ED - Ottosen, L. T1 - Electrochemical investigation of carbon-based conductive coatings for application as anodes in ICCP system of reinforced concrete structures T2 - Electrochemistry in Civil Engineering N2 - 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. T2 - International RILEM Conference on Materials, Systems and Structures in Civil Engineering 2016 CY - Lyngby, Denmark DA - 21.08.2016 KW - ICCP KW - Coating KW - Cunductive KW - Corrosion KW - reinforcement KW - Concrete KW - Cathodic protection PY - 2016 SN - 978-2-35158-176-6 SN - 978-2-35158-177-3 VL - Proceedings PRO 111 SP - 43 EP - 46 PB - RILEM Publications S.A.R.L. CY - Paris, France AN - OPUS4-37216 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ebell, Gino A1 - Mietz, Jürgen A1 - Burkert, Andreas T1 - Investigation of chloride-induced pitting corrosion of steel in concrete by a combination of electrochemical methods with X-ray tomography T2 - EUROCORR 2014 - European corrosion congress N2 - 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. T2 - EUROCORR 2014 - European corrosion congress CY - Pisa, Italy DA - 08.09.2014 KW - Corrosion KW - Rebar KW - Chloride KW - Pitting corrosion PY - 2014 SN - 978-3-89746-159-8 SP - O-7207, 274-275 AN - OPUS4-31431 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ebell, Gino A1 - Poltavtseva, Marina A1 - Mietz, Jürgen T1 - Electrochemical investigation of carbon-based conductive coatings for application as anodes in ICCP system of reinforced concrete structures T2 - EUROCORR 2014 - European corrosion congress N2 - 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. T2 - EUROCORR 2014 - European corrosion congress CY - Pisa, Italy DA - 08.09.2014 KW - Cathodic protection KW - Concrete KW - ICCP PY - 2014 SN - 978-3-89746-159-8 SP - O-7489, 481 EP - O-7489, 481 AN - OPUS4-31430 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ebell, Gino A1 - Burkert, Andreas A1 - Mietz, Jürgen T1 - Hydrogen evolution on galvanized rebar in fresh concrete with different chromate-reduced cements T2 - EUROCORR 2015 - European corrosion congress (Proceedings) N2 - The reduction of the chromate contents in cements affects the electrochemical reactions of galvanized reinforcing steels in fresh concrete. It is important to investigate the critical conditions in the first hours following the pouring of the concrete. T2 - EUROCORR 2015 - European corrosion congress CY - Graz, Austria DA - 06.09.2015 KW - Hydrogen evolution KW - Concrete KW - Galvanized rebar KW - Reinforcement KW - Chromate PY - 2015 SP - paper 9_703 AN - OPUS4-34619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Poltavtseva, Marina A1 - Ebell, Gino A1 - Mietz, Jürgen T1 - Electrochemical investigations of carbon-based conductive coatings for application as anodes in ICCP systems of reinforced concrete structures JF - Materials and corrosion N2 - 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 200 Ω. 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. KW - Cathodic protection KW - Corrosion KW - Rebar KW - Reinforcement KW - Concrete KW - Potential PY - 2015 DO - https://doi.org/10.1002/maco.201407680 SN - 0947-5117 SN - 1521-4176 VL - 66 IS - 7 SP - 627 EP - 634 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-33709 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ebell, Gino A1 - Burkert, Andreas A1 - Mietz, Jürgen T1 - Corrosion behavior of galvanized reinforcement in chloride containing mortar and carbonated mortar T2 - Intergalva 2018 N2 - Korrosionseigenschaften von feuerverzinktem Betonstahl unterscheiden sich grundlegend von herkömmlichen Betonstahl. In diesem Vortrag sind Beispiele für das Korrosionsverhalten in chloridhaltigen und carbonatisierten Mörteln dargestellt T2 - Intergalva 2018 - 25th International Galvanizing Conference CY - Berlin, Germany DA - 17.06.2018 KW - Corrosion KW - Korrosion KW - Verzinkt KW - Betonstahl PY - 2018 SP - 301 EP - 309 AN - OPUS4-45240 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gluth, Gregor A1 - Ebell, Gino A1 - Hlavacek, Petr A1 - Mietz, Jürgen T1 - Chloride‐induced steel corrosion in alkali‐activated fly ash mortar: Increased propensity for corrosion initiation at defects JF - Materials and Corrosion N2 - Chloride contents at the steel–mortar interface that initiate steel corrosion were determined for carbon steel in alkali‐activated fly ash mortar for three different exposure conditions: exposure to 1 M NaCl solution; leaching in deionized water and then exposure to 1 M NaCl solution; and leaching in deionized water, aging in air at 20°C and natural CO2 concentration, and then exposure to 1 M NaCl solution. For comparison, a Portland cement mortar, exposed to 1 M NaCl solution, was studied. The median values of the corrosion‐initiating chloride contents (average over the full length of the rebar) in the alkali‐activated fly ash mortar varied between 0.35 and 1.05 wt% Cl with respect to binder, consistently lower than what was obtained for the Portland cement mortar, but with no clear trend regarding the exposure conditions. For most of the alkali‐activated fly ash mortar specimens, preferential corrosion at the connection between the working electrode and the external measurement setup was observed, while preferential corrosion did not occur for the Portland cement mortar. Scanning electron microscopy and auxiliary experiments in synthetic solutions indicated that this behavior was caused by inhomogeneities at the steel–mortar interface in the alkali‐activated mortar, likely due to its peculiar rheological properties in the fresh state. KW - Alkali-activated materials KW - Steel corrosion KW - Critical chloride content KW - Steel-concrete interface PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-507268 DO - https://doi.org/10.1002/maco.202011541 VL - 71 IS - 5 SP - 749 EP - 758 PB - Wiley-VCH AN - OPUS4-50726 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Burkert, Andreas A1 - Ebell, Gino A1 - Eichler, T. A1 - Hariri, K. A1 - Harnisch, J. A1 - Keßler, S. A1 - Mayer, T. A1 - Meier, J. A1 - Mietz, Jürgen A1 - Reichling, K. A1 - Sodeikat, C. T1 - Electrochemical half-cell potential measurements for the detection of reinforcement corrosion T2 - Electrochemical Half-Cell Potential Measurements for the Detection of Reinforcement Corrosion N2 - This specification describes the application of electrochemical half‐cell potential measurements (frequently also called potential mapping) for the detection of reinforcement corrosion in reinforced concrete structures. Areas of corroding reinforcement steel can be located in a nondestructive manner by means of this procedure. Half‐cell potential measurements are used in order to detect chloride‐induced corrosion. However, it is not recommended in order to assess the risk of carbonation‐induced corrosion. For this purpose the determination of the carbonation depth and the concrete cover appear to be more appropriate. The content of this specification exclusively refers to the application of mobile, local variable reference electrodes, which are only placed on the concrete surface while measuring. The technique distinguishes itself thereby from the range of corrosion monitoring systems with stationary installed reference electrodes and sensor systems, respectively, whereby it is possible to continuously track measurements within the area of the installed electrodes. However, these methods are not dealt with in this specification. KW - Monitoring KW - Corrosion KW - Reinforcement PY - 2014 SN - 978-940283-72-6 SP - B 03, 1 EP - 19 PB - DGZfP CY - Berlin AN - OPUS4-40419 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gluth, Gregor A1 - Hlavacek, Petr A1 - Reinemann, Steffi A1 - Ebell, Gino A1 - Mietz, Jürgen ED - Alexander, M.G. ED - Beushausen, H. ED - Dehn, F. ED - Moyo, P. T1 - Leaching, carbonation and chloride ingress in reinforced alkali-activated fly ash mortars T2 - International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2018) N2 - 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. T2 - International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2018) CY - Cape Town, South Africa DA - 19.11.2018 KW - Alkali-activated materials KW - Steel corrosion KW - Leaching KW - Carbonation PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-464381 DO - https://doi.org/10.1051/matecconf/201819902025 VL - 199 SP - Article Number 02025 PB - EDP Sciences AN - OPUS4-46438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hlavacek, Petr A1 - Gluth, Gregor A1 - Reinemann, Steffi A1 - Ebell, Gino A1 - Kühne, Hans-Carsten A1 - Mietz, Jürgen T1 - Corrosion of steel reinforcement in geopolymer mortars - carbonation resistance, chloride migration, and preliminary corrosion potential data T2 - EUROCORR 2017 N2 - Alkali-activated materials such as geopolymers are currently receiving a lot of attention because of their potential to be used as binders for concrete with advantageous engineering properties and reduced manufacturing CO2 emissions. Knowledge of the durability of steel in these concretes and related properties of alkali-activated materials is a prerequisite for their application as building materials, if they are to be used for steel reinforced elements. However, to date only limited data exists on this topic. The present contribution focuses on durability-related transport properties of geopolymer-based mortars (as model systems for concrete). We report results of accelerated carbonation, rapid chloride migration (RCM) and air permeability measurements as well as porosity data for fly ash-based geopolymer mortars, including mixes containing ground granulated blast furnace slag (GGBFS). In addition, we report polarization resistance data and corrosion potential vs. time curves for carbon steel bars embedded in two of the fly ash-based geopolymer mortars and a CEM I-based mortar (as reference). Despite comparable total porosities, the carbonation depths, the chloride migration coefficients and the air permeabilities of the mortars differed significantly. In general, the addition of GGBFS to the binders improved the performance (decreased transport coefficients); however, this was not found to be true for the air permeability in all cases. This latter effect can be explained by drying damage of the C-(A-)S-H gel in GGBFS-containing binders. On the other hand, low transport coefficients can also be achieved by optimization of the binder formulation without the addition of GGBFS, which is also reflected in the material’s air permeability. Thus, there exists no simple correlation between air permeability (of harshly dried mortars) and durability-related transport coefficients for the studied alkali-activated materials. The corrosion potential vs. time curves in combination with polarization resistance values reveal that the steel reinforcement in geopolymer mortars assumed a passive state. However, this happened considerably later than for steel in CEM I-based mortars. The free corrosion potential of carbon steel reinforcement in the geopolymer mortars had different values than the free corrosion potential values for the CEM I-based mortar for both the active and the passive state; possible reasons for this behavior are discussed. T2 - EUROCORR 2017 CY - Prague, Czech Republic DA - 03.09.2017 KW - Geopolymers KW - Alkali-activated materials KW - Corrosion KW - Steel reinforcement KW - Concrete PY - 2017 SP - Paper 87351, 1 EP - 7 AN - OPUS4-41870 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ebell, Gino A1 - Burkert, Andreas A1 - Mietz, Jürgen T1 - Detection of reinforcement corrosion in reinforced concrete structures by potential mapping: Theory and practice JF - International Journal of Corrosion N2 - Electrochemical potential mapping according to guideline B3 of DGZfP (German Society for Nondestructive Testing) is a recognized technique for the localization of corroding reinforcing steels. In reinforced concrete structures the measured potentials are not necessarily directly linked to the corrosion likelihood of the reinforcing steel. The measured values may be significantly affected, different from, e.g., stress measurement, by different influences on the potential formation at the phase boundary metal/concrete itself as well as the acquisition procedure. Due to the complexity of influencing factors there is a risk that the results are misinterpreted. Therefore, in a training concept firstly the theoretical basics of the test method should be imparted. Then, frequently occurring practical situations of various influencing factors will be made accessible to the participants by a model object specially designed for this purpose. The aim is to impart profound knowledge concerning the characteristics of potential mapping for detecting corrosion of reinforcing steel in order to apply this technique in practice as reliable and economical test method. KW - Corrosion KW - Potential mapping KW - Korrosion KW - Potentialfeldmessung PY - 2018 DO - https://doi.org/10.1155/2018/3027825 SN - 1687-9333 SN - 1687-9325 VL - 2018 SP - Article 3027825, 1 EP - 6 PB - Hindawi AN - OPUS4-46206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hlavacek, Petr A1 - Reinemann, Steffi A1 - Gluth, Gregor A1 - Ebell, Gino A1 - Mietz, Jürgen ED - Serdar, M. ED - Stirmer, N. ED - Provis, J. T1 - Behaviour of reinforced alkali-activated fly ash mortars under leaching conditions T2 - Proceedings of the International Conference on Sustainable Materials, Systems and Structures (SMSS2019), Vol. 1: New Generation of Construction Materials N2 - Corrosion of steel reinforcement in concrete is one of the major deterioration mechanisms limiting the service life of reinforced concrete structures. While for conventional (Portland cement-based) concretes a great amount of experience exists in this regard, the factors that determine the onset of reinforcement corrosion in alkali-activated materials are incompletely understood yet. One aspect of corrosion protection is leaching and the accompanying changes of the concrete pore solution. In the present study, alkali-activated fly ash mortars with embedded carbon steel rebars were exposed to de-ionised water for periods up to 330 days, and the electrochemical response of the steel (free corrosion potential, polarisation resistance), the alteration of the mortar (ohmic resistance, mechanical strength, pore size distribution) as well as the pore solution composition were monitored. Although substantial alkali leaching was observed, the pH of the pore solution remained at values sufficient to protect the embedded steel from depassivation. The mortar did not exhibit indications of significant deterioration. Thus, the present results suggest that leaching is not critical for protection of steel reinforcement in alkali-activated fly ash mortars and concretes. T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019) CY - Rovinj, Croatia DA - 20.03.2019 KW - Alkali-activated materials KW - Steel corrosion KW - Leaching PY - 2019 SN - 978-2-35158-223-7 VL - 1 SP - 118 EP - 124 PB - RILEM Publications CY - Paris AN - OPUS4-47585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -