TY - JOUR A1 - Mietz, Jürgen T1 - Investigations on hydrogen-induced embrittlement of quenched and tempered prestressing steels N2 - In Germany in recent years failures of more than 30-year-old prestressed concrete structures have been observed. In all these cases a quenched and tempered steel type, strength class St. 1420/1570 was used. In order to assess the corrosion risk, i.e. crack initiation and propagation, under depassivating conditions lifetime tests in environments relevant for building practice were carried out using different prestressing steels of this quenched and tempered type of material. From the results it can be concluded that the specific susceptibility of certain prestressing steels is the determining factor with respect to the occurrence of cracks rather than environmental factors. Translated Abstract Untersuchungen zum wasserstoffinduzierten Sprödbruch vergüteter Spannstähle In den letzten Jahren ist es verschiedentlich zu Schadensfällen von Spannbetonbauteilen gekommen, bei denen vergüteter Spannstahl der Festigkeitsklasse St 1420/1570 eingesetzt war. Durch systematische Untersuchungen an verschiedenen Typen dieser Stahlsorte sollte geklärt werden, ob unter depassivierenden Bedingungen Rißeinleitung und -ausbreitung unter praxisnahen Verhältnissen zu erwarten ist. Die durchgeführten Untersuchungen lassen folgern, daß die spezifische Anfälligkeit des Spannstahls für das Auftreten von Rissen einen wesentlich höheren Einfluß besitzt als die elektrolytseitigen Parameter, da sich die verschiedenen Stähle auch bei vergleichbaren Korrosionsangriffen unterschiedlich verhalten. KW - Prestressing steels KW - Corrosion PY - 2000 U6 - https://doi.org/10.1002/(SICI)1521-4176(200002)51:2<80::AID-MACO80>3.0.CO;2-A SN - 0947-5117 SN - 1521-4176 N1 - Sprachen: Deutsch/Englisch - Languages: German/English VL - 51 IS - 2 SP - 80 EP - 90 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-807 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mietz, Jürgen A1 - Fischer, Joachim A1 - Isecke, Bernd T1 - Spannungsrißkorrosion an Spannstählen N2 - Im Rahmen einer Bauwerksuntersuchung an einer in nachträglicher Verbundbauweise hergestellten Brücke wurden Anrisse an Spannstählen der Quervorspannung festgestellt, ohne daß Verpreßmängel oder korrosionsfördernde Substanzen vorlagen. Bei dem verwendeten Werkstoff handelt es sich um einen in der ehemaligen DDR hergestellten vergüteten Stahl der Festigkeitsklasse St 140/160. Ursache für die Anrisse ist die in Laborversuchen nachgewiesene Empfindlichkeit dieses Stahles gegenüber wasserstoffinduzierter Spannungsrißkorrosion, die unter ungünstigen Bedingungen dazu führen kann, daß Vorschädigungen vor dem Verpressen eintreten. Zusätzlich durchgeführte Magnetpulverprüfungen an ausgewählten Bereichen der Längsvorspannung ergaben keinerlei Hinweise auf Anrisse. Translated Abstract Stress corrosion cracking of prestressing steels During the investigation of a post-tensioned bridge structure incipient cracks of the prestressing steels of the transverse prestressed members were observed. Defects related to non-injected ducts or the presence of corrosion inducing substances could not be detected. The prestressing steel used is a quenched and tempered steel, strength class St 140/160, which was produced in the former GDR. The cause for the cracks is the susceptibility of this type of steel to hydrogen-induced stress corrosion cracking as could be shown in laboratory tests. Under unfavourable conditions cracks can be initiated before grouting. Additional magnetic particle tests at selected areas of the longitudinal prestressed members did not indicate any signs for incipient cracks. KW - Corrosion PY - 1999 SN - 0947-5117 SN - 1521-4176 VL - 50 IS - 9 SP - 535 EP - 540 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-831 LA - deu 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 U6 - 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 - Broomfield, J. A1 - Fischer, Joachim A1 - Mietz, Jürgen A1 - Schneck, U. T1 - Case studies N2 - In this paper, some quite different survey tasks are described, and it can be seen that corrosion surveys will follow a certain scheme of data acquisition (first NDT measurements, than detailed testing on suspect areas), but the individual scope of on-site measurements may have a vast variety according to the local circumstances, and the interpretation always has to refer to a wider set of information than the data readings only. KW - Corrosion surveys KW - Non-destructive testing KW - Reinforcement KW - Concrete KW - Potential mapping KW - Corrosion PY - 2013 U6 - https://doi.org/10.1002/maco.201206649 SN - 0947-5117 SN - 1521-4176 VL - 64 IS - 2 SP - 147 EP - 160 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-29730 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Ebell, Gino A1 - Achenbach, R. A1 - Angst, U. A1 - Brem, M. A1 - Dauberschmidt, C. A1 - Eichler, T. A1 - Hariri, K. A1 - Harnisch, J. A1 - Keßler, S. A1 - Mayer, T.F. A1 - Mietz, Jürgen A1 - Pruckner, F. T1 - Merkblatt B 03 - Elektrochmische Potentialmessung zur Detektion von Bewehrungsstahlkorrosion N2 - Die Potentialmessung kann zum Auffinden korrosionsaktiver Bereiche neben Stahlbetonbauwerken auch bei Spannbetonbauwerken angewandt werden, die mit Spannstählen im direkten Verbund hergestellt werden. Bei Vorspannsystemen mit metallischen Hüllrohren im nachträglichen Verbund ist eine Aussage über den Korrosionszustand des Hüllrohrs, nicht aber des Spannstahls möglich. Messungen an Spannbetonbauteilen erfordern grundsätzlich die besonderen Kenntnisse eines Spezialisten. KW - Korrosion KW - Potentialfeldmessung KW - Corrosion KW - Concrete PY - 2021 SN - 978-3-947971-16-9 SP - 1 EP - 22 PB - DGZfP CY - Berlin AN - OPUS4-53091 LA - deu 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 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 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 - 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 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 U6 - 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 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 -