TY - JOUR A1 - Mietz, Jürgen A1 - Burkert, Andreas A1 - Eich, Gerd A1 - Raupach, M. T1 - Development of a new combined corrosion protection system for chloride-contaminated reinforced concrete structures N2 - Chloride-induced damage of reinforcing steel is especially for parking garages and bridges often very severe as large amounts of chlorides act on horizontal surfaces which could lead to fast ingress of these detrimental ions up to the level of the reinforcement and subsequently to high rates of corrosion. In order to avoid the disadvantages of conventional rehabilitation (unreliable prognosis with patch repair or high costs and regular maintenance with cathodic protection using impressed current) a new combined protection system was developed where the principle of drying out the concrete (by means of a surface protection system) is combined with a temporary cathodic protection (by means of a sprayed zinc layer) during the transitional period of the drying out process. This new system was tested both in the laboratory and on-site at a pilot application. Based on the results obtained the possibilities and limitations of the new system are discussed in this paper. KW - Chlorid-induced corrosion KW - Reinforcing steel KW - Cathodic protection KW - Sprayed zinc layer KW - Surface protection system PY - 2005 DO - https://doi.org/10.1002/maco.200403836 SN - 0947-5117 SN - 1521-4176 VL - 56 IS - 2 SP - 104 EP - 110 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-7157 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mietz, Jürgen A1 - Burkert, Annette A1 - Burkert, Andreas A1 - Eich, Gerd T1 - Investigations on the protection effect of filling materials for post-tensioning systems under construction conditions N2 - About the long-term protection behaviour of corrosion protection materials (filling materials) for prestressed systems under critical environmental conditions is only little known. The corrosion protection effect is usually based on theoretical considerations and is proven by short-term tests. The selection of the different products is mainly made according to economical or workability criteria. In a research project the barrier effect of different commercial corrosion protection materials (waxes as well as oil-based greases) against water, their tendency for undercutting as well as their additional corrosion protection effect were investigated. The exposure tests were carried out with non-stressed as well as stressed prestressing steel specimens which were subjected to critical conditions (condensed water, artificial soil solution, direct soil contact). Parallel to these long-term exposure tests the applicability of different electrochemical techniques and their significance with respect to testing the corrosion protection ability and water absorption was evaluated. Within the project a suitable method for simple testing the performance of corrosion protection materials under real conditions was developed. By means of a small compact cell submicroscopical reactions of the used sensors could be measured. The high sensitivity of this measuring technique enables the detection of degradation processes at thin protection layers. KW - Prestressed systems KW - Corrosion KW - Corrosion protection KW - Electrochemical tests KW - Grease KW - Wax PY - 2006 DO - https://doi.org/10.1002/maco.200603986 SN - 0947-5117 SN - 1521-4176 VL - 57 IS - 11 SP - 843 EP - 851 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-13931 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eich, Gerd A1 - Burkert, Annette A1 - Burkert, Andreas A1 - Mietz, Jürgen T1 - Einsatz des nichtrostenden Duplex-Stahls 1.4362 als preisgünstige Alternative im Bauwesen N2 - Aufgrund der in den letzten Jahren stark angestiegenen Rohstoffpreise sind die im Bauwesen häufig eingesetzten nichtrostenden Standardaustenite in vielen Fällen nicht mehr wettbewerbsfähig. Eine deutlich kostengünstigere Alternative stellt der Duplex-Stahl 1.4362 dar, der bisher aber noch nicht bauaufsichtlich zugelassen ist. Mit Hilfe von Auslagerungsversuchen sowie elektrochemischen Untersuchungen sollte das Korrosionsverhalten dieses Werkstoffs unter neutralen bis leicht sauren, chloridhaltigen Umgebungsbedingungen, wie sie in vielen Bereichen des Bauwesens vorkommen, geklärt werden. Insgesamt belegen die Ergebnisse, dass der kostengünstigere Werkstoff 1.4362 für baupraktische Anwendungen eine Alternative für Anwendungen darstellen kann, in denen bisher die Werkstoffe 1.4404 oder 1.4571 eingesetzt wurden. KW - Duplex-Stähle KW - Nichtrostende Stähle KW - Auslagerungsversuche KW - Elektrochemische Versuche KW - Lochkorrosionspotential KW - Spaltkorrosionspotential PY - 2007 DO - https://doi.org/10.1002/stab.200710094 SN - 0038-9145 SN - 1437-1049 SN - 0932-6375 VL - 76 IS - 12 SP - 898 EP - 904 PB - Ernst CY - Berlin AN - OPUS4-16364 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mietz, Jürgen A1 - Burkert, Andreas A1 - Lehmann, Jens A1 - Burkert, Annette A1 - Eich, Gerd T1 - Galvanised constructional elements in contact with prestressing steel tendons N2 - In order to clarify under which practical conditions real risks for hydrogen-induced stress corrosion cracking of prestressing steels exist laboratory investigations in aqueous solutions and concrete as well as tests with stressed prestressing steels were carried out. While different distances between steel and zinc (cathode and anode) showed only a negligible influence on the polarisation of the steel a significant dependence on the area ratio steel/zinc was observed. A critical area ratio of 10:1 can be defined above which polarisation of the steel to hydrogen evolution potentials is unlikely. The results obtained in the laboratory concerning the critical area ratio were confirmed by on-site investigations in a precasting plant. Exposure tests with hydrogen loading did not lead to fractures during the testing time for approved prestressing steels. The characteristic mechanical values determined immediately after the hydrogen loading tests did not show significant changes. Thus, an indirect contact between prestressing steels and galvanised elements can be estimated as uncritical. But a direct contact has to be excluded by compliance with DIN 1045-1, i.e minimal distance of 2 cm between prestressing steel and galvanised elements. PY - 2008 DO - https://doi.org/10.1002/maco.200804114 SN - 0947-5117 SN - 1521-4176 VL - 59 IS - 2 SP - 131 EP - 138 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-16724 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Burkert, Andreas A1 - Lehmann, Jens A1 - Burkert, Annette A1 - Mietz, Jürgen T1 - Damage of stainless steel bars due to atmospheric corrosion N2 - In addition to constructional requirements in civil engineering stainless steels often have to fulfil high visual demands. Unexpected impairments of the visual appearance of stainless steels under low corrosive conditions are a widespread problem today. Frequently it is supposed that this is caused by changes in the alloy composition, worse environmental conditions or improper handling. Within a research project the systematic investigation of several cases of damaged stainless steel bars has shown that the reasons are based on well-known material defects like chemical inhomogeneities (e.g. precipitations or local carburization) or geometrical defects (e.g. undercuts, rolling defects or shell formation). Thus, the failures could be clearly identified as production failures of the respective semi-finished products. KW - Atmospheric corrosion KW - EPR test KW - Failure KW - Intercrystalline corrosion KW - Stainless steel KW - Nichtrostender Stahl KW - Werkstoffauswahl KW - Dauerhaftigkeit KW - Korrosion PY - 2012 DO - https://doi.org/10.1002/maco.201005701 SN - 0947-5117 SN - 1521-4176 VL - 63 IS - 3 SP - 264 EP - 270 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-25702 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Burkert, Andreas A1 - Lehmann, Jens A1 - Burkert, Annette A1 - Mietz, Jürgen A1 - Gümpel, P. T1 - Technische und wirtschaftliche Alternativen zu den klassischen nichtrostenden, austenitischen Stählen unter atmosphärischen Einsatzbedingungen N2 - Durch systematische Labor- und Auslagerungsuntersuchungen ist es möglich, sieben unterschiedliche nichtrostende Stahllegierungen hinsichtlich verschiedenster Anwendungen untereinander und auch in Bezug auf zwei austenitische Standardwerkstoffe (1.4301, 1.4404) zu vergleichen. Die parallele Untersuchung von fünf verschiedenen Oberflächenausführungen der jeweiligen Werkstoffe ermöglicht zudem, branchenspezifische Besonderheiten der Oberflächenausführung beim Werkstoffvergleich zu berücksichtigen. Der Einfluss der Oberflächenausführung wird überwiegend bei den Ergebnissen der Auslagerungsversuche in kritischen Atmosphären sichtbar, weniger bei den elektrochemischen Untersuchungen. Die drei Vertreter aus dem Bereich der Duplexstähle zeigten unter den meisten Untersuchungsbedingungen eine hervorragende Korrosionsbeständigkeit. Insbesondere für Anwendungen im Bauwesen können die Lean-Duplexstähle deutliche Vorteile bieten. Der Manganaustenit 1.4376 sowie der Ferrit 1.4509 sind nur eingeschränkt als Alternativen geeignet, da die Werkstoffe bei einigen Versuchen signifikante Schwächen zeigten.--------------------------------------------------------------------------- The systematic laboratory and field exposure tests allow to compare seven different stainless steels among each other and also regarding two standard austenitic materials (1.4301, 1.4401) with respect to various applications. Parallel investigations with five different surface finishes of the respective materials enable to consider also industry-specific features of the surface finish. The influence of the surface finish can mainly be seen in the results of the exposure tests in critical atmospheres and less in the electrochemical investigations. The three duplex stainless steels showed under most of the test conditions excellent corrosion resistance. Especially for applications in civil engineering the lean duplex steels offer clear advantages. The manganese alloyed 1.4376 and the ferritic steel 1.4509 are only limited suitable as alternatives as these materials showed significant weaknesses in some of the tests. KW - Nichtrostende Stähle KW - Bauwesen KW - Atmosphärische Korrosion PY - 2012 DO - https://doi.org/10.1002/stab.201201624 SN - 0038-9145 SN - 1437-1049 SN - 0932-6375 VL - 81 IS - 11 SP - 875 EP - 888 PB - Ernst CY - Berlin AN - OPUS4-26825 LA - deu 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 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 - 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 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 - Burkert, Andreas A1 - Mietz, Jürgen T1 - Hydrogen evolution on galvanized rebar in fresh concrete with different chromate-reduced cements 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 - Ebell, Gino A1 - Burkert, Andreas A1 - Lehmann, Jens A1 - Mietz, Jürgen T1 - Korrosions- und Verbundverhalten verzinkter Betonstähle in Betonen mit chromatreduzierten Zementen N2 - Durch die Absenkung des Chromatgehalts der Zemente verändern sich die elektrochemischen Reaktionen von verzinkten Betonstählen in der Frischbetonphase. Mit Hilfe von elektrochemischen Messungen sowie Stabauszugsversuchen wurde an chromathaltigen und chromatreduzierten Zementen die Auswirkung des Chromats auf die Deckschichtbildung am Zink und auf das Verbundverhalten untersucht. Mit den Ergebnissen konnte eine Beeinträchtigung der Verbundzone als Folge der Chromatreduzierung für die Zementarten CEM I und CEM II nachgewiesen werden. Die Störung der Verbundzone ist in Bezug auf die sich ausbildende Porenstruktur als dauerhaft anzusehen. Die Auswirkungen auf das Verbundverhalten werden mit zunehmendem Betonalter weitgehend kompensiert. Die Ergebnisse der bezogenen Verbundspannung bei Verschiebewegen von 0,1 mm und 0,5 mm liegen trotz der Gefügestörung noch im Bereich der Erwartungswerte für den unverzinkten Betonstahl. Unter baupraktischen Gesichtspunkten muss die auftretende Gefügestörung hinsichtlich der Verbundspannung daher keine Berücksichtigung finden. KW - Verzinkt KW - Feuerverzinkt KW - Betonstahl KW - Verbund PY - 2011 DO - https://doi.org/10.1002/best.201100038 SN - 0005-9900 SN - 1437-1006 VL - 106 IS - 9 SP - 629 EP - 639 PB - Ernst CY - Berlin AN - OPUS4-24307 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -