TY - CONF A1 - Beck, Matthias A1 - Goebbels, Jürgen A1 - Burkert, Andreas T1 - Monitoring of Corrosion Processes in Chloride Contaminated Mortar by X-Ray Tomography T2 - Proceedings of the 1st International Conference Corrosion and Material Protection and 10th conference AKI 2007 KW - Self-corrosion KW - X-ray tomography KW - Reinforcement KW - Concrete parameters KW - Metallographic section PY - 2007 SN - 978-80-903933-0-1 SP - 1 EP - 6 (Paper 012) PB - SVUOM CY - Prag AN - OPUS4-15894 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Beck, Matthias A1 - Goebbels, Jürgen A1 - Burkert, Andreas A1 - Isecke, Bernd A1 - Bäßler, Ralph T1 - Monitoring of corrosion processes in chloride contaminated mortar by electrochemical measurements and X-ray tomography JF - Materials and corrosion N2 - Corrosion of steel reinforcement in concrete exposed to chloride containing environments is a serious problem in civil engineering practice. Electrochemical methods, e.g., potential mapping, provide information whether the steel reinforcement is still passive or depassivation has been initiated. By applying such techniques no information on the type of corrosion, its extent and distribution of corrosion products is available. Particular the corrosion progress is a significant problem. Especially in the case of macrocell corrosion in reinforced concrete structures, the development at the anode cannot be separated into corrosion damage resulting from macrocell corrosion or self-corrosion. Until now also in laboratory tests it is impossible to collect such information without destroying specimens after electrochemical testing was performed. To overcome this problem it was tried to study the steel surface within the mortar specimens by X-ray tomography (CT). Within the scope of these investigations it could be shown, that X-ray tomography is suitable to make corrosion pits and their development visible which are embedded in a mortar with a cover thickness of about 35 mm. In this publication the time-dependent corrosion damage of reinforced steel is documented by X-ray tomography. KW - Self-corrosion KW - X-ray tomography KW - Concrete parameters KW - Contaminated mortar KW - Electrochemical measurements KW - Pitting corrosion PY - 2010 DO - https://doi.org/10.1002/maco.200905364 SN - 0947-5117 SN - 1521-4176 VL - 61 IS - 6 SP - 475 EP - 479 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-22848 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Beck, Matthias A1 - Goebbels, Jürgen A1 - Isecke, Bernd A1 - Burkert, Andreas A1 - Mietz, Jürgen T1 - Investigations of corrosion on small cathodes in reinforced concrete - observations and suggestions T2 - EUROCORR 2009 - Corrosion from the nanoscale to the plant N2 - 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. T2 - EUROCORR 2009 CY - Nice, France DA - 2009-09-06 KW - Self-corrosion KW - Steel reinforcement KW - Concrete parameters KW - X-ray tomography PY - 2009 IS - Paper 7976 SP - 1 EP - 13 AN - OPUS4-20063 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Beck, Matthias A1 - Goebbels, Jürgen A1 - Meinel, Dietmar A1 - Burkert, Andreas ED - M.G. Alexander, ED - H.-D. Beushausen, ED - F. Dehn, ED - P. Moyo, T1 - DFG Research Group 537: Modelling reinforcement corrosion - Observation and monitoring of self-corrosion processes in chloride contaminated mortar by X-ray tomography T2 - Proceedings of the international conference on concrete repair, rehabilitation and retrofitting II T2 - 2nd International Conference on Concrete Repair, Rehabilitation and Retrofitting CY - Cape Town, South Africa DA - 2008-11-24 KW - Self-corrosion KW - X-ray tomography KW - Reinforcement KW - Concrete parameters KW - Metallographic section KW - Steel surface PY - 2009 SN - 978-0-415-46850-3 SP - 187 EP - 188 PB - CRC Press CY - Boca Raton AN - OPUS4-18438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Goebbels, Jürgen A1 - Beck, Matthias A1 - Isecke, Bernd A1 - Burkert, Andreas A1 - Bäßler, Ralph ED - Castro-Borges, P. ED - Moreno, E.I. ED - Sakai, K. ED - Gjorv, O.E. ED - Banthia, N. T1 - Self-corrosion of steel in concrete by electrochemical measurements and X-ray tomography T2 - CONSEC`10 - Concrete under severe conditions - Environment and loading (Proceedings) T2 - CONSEC`10 - 6th International conference on concrete under severe conditions CY - Mérida, Yucatán, Mexico DA - 2010-06-07 KW - Self-corrosion KW - Steel KW - Concrete KW - X-ray tomography PY - 2010 SN - 978-0-415-59316-8 VL - 2 SP - 1221 EP - 1228 PB - Taylor & Francis CY - London, UK AN - OPUS4-22299 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Goebbels, Jürgen A1 - Isecke, Bernd A1 - Beck, Matthias A1 - Burkert, Andreas A1 - Bäßler, Ralph T1 - Monitoring of corrosion processes in chloride contaminated mortar by electrochemical measurements and X-ray tomography T2 - EUROCORR 2008 - Managing corrosion for sustainability N2 - Corrosion of steel reinforcement in concrete exposed to chloride containing environments is a serious problem in civil engineering practice. Electrochemical methods, e.g. potential mapping, provide information whether the steel reinforcement is still passive or depassivation has been initiated. By applying such techniques no information on the type of corrosion, its extent and distribution of corrosion products is available. Particular the corrosion progress is a significant problem. Especially in the case of element corrosion in reinforced concrete structures, the development at the anode can not be separated into corrosion damage causing by element corrosion or self-corrosion. Until now also in laboratory tests it is impossible to collect such information without destroying specimens after electrochemical testing was performed place. To overcome this problem it was tried to study the steel surface within the mortar specimens by X-ray tomography (CT). Within the scope of these investigations it could be shown, that X-ray tomography is suitable to make corrosion pits visible which are embedded in a mortar with a cover thickness of about 35 mm. In this publication the corrosion damage of reinforced steel is documented timedependent by X-ray tomography. T2 - EUROCORR 2008 CY - Edinburgh, Scotland, UK DA - 2008-09-07 KW - Self-corrosion KW - X-ray tomography KW - Reinforcement KW - Concrete parameters PY - 2008 N1 - Serientitel: EFC-Event – Series title: EFC-Event IS - 299 SP - 1 EP - 10 PB - DECHEMA CY - Frankfurt am Main AN - OPUS4-17868 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoferer, J. A1 - Hoffmann, L.M. A1 - Goebbels, Jürgen A1 - Last, G. A1 - Weil, W. A1 - Kasper, G. T1 - Reconstruction algorithms for the internal packing density distribution of fibrous filter media based on tomographic data JF - Filtration N2 - Algorithms were developed to approximate the 3-dimensional internal packing density distributions of fibrous filter media at different levels of detail and complexity. Each algorithm uses certain input information derived from X-ray tomographic data of filter samples. Algorithm 1 creates a binary media structure consisting of the true (i.e. tomographically determined) void distribution plus regions of uniform packing density. The average packing density of the media is maintained constant. Algorithm 2 creates a model fibrous structure of straight fibres of equal diameter and random length positioned randomly in space, while maintaining the true (i.e. tomographically determined) fibre orientation distribution. The number and length of the fibres on average adds up to the packing density of the filter. The model fibrous structure is recreated by a stationary Poisson process of convex bodies. Algorithm 3 distributes pores of random size and location within a homogeneous matrix, such that the average packing density again coincides with the true (i.e. tomographically determined) packing density. This algorithm is also based on a stationary Poisson process of convex bodies. The capability of each algorithm to recreate the essential structural features of the media was tested against 'reality' by computing the respective overall pressure drop of the filter as well as the velocity distribution in the filter interior, and comparing with the results obtained for the 'true' packing density distribution of a sample measured by tomography. Compared to the assumption of a completely homogenous filter (which gives roughly 2 times the actual Δp), all algorithms are closer to reality. The binary algorithm deviates in Δp by a factor of 1.8; algorithm 3 comes within a factor of 1.6 of the true Δp. The best approximation is by algorithm 2 which narrows the difference in Δp to a factor of 1.4. KW - X-ray tomography KW - Fibrous filter KW - Packing density PY - 2009 SN - 1479-0602 VL - 9 IS - 2 SP - 147 EP - 154 PB - Filtration Solutions CY - Newbold, Coleorton, Coalville AN - OPUS4-22880 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nusser, K. A1 - Mosbauer, T. A1 - Schneider, G.J. A1 - Brandt, K. A1 - Weidemann, Gerd A1 - Goebbels, Jürgen A1 - Riesemeier, Heinrich A1 - Göritz, D. T1 - Silica dispersion in styrene butadiene rubber composites studied by synchrotron tomography JF - Journal of non-crystalline solids N2 - By means of synchrotron X-ray computed tomography, model composites consisting of silica and styrene–butadiene rubber were studied with a very high spatial resolution. By our analysis technique we were able to determine the nano- and micro dispersion from the experimental results by our numerical analysis. These results are discussed with respect to crucial advantages of the generically 3-dimensional tomography technique as compared to 2-dimensional methods. Our quantitative analysis of the 3d images demonstrates that in the case of our model composites the filler dispersion is good, independent on the filler concentration. Our new 3-dimensional results evidence that considering only 2-d pictures may lead to ambiguities that can lead to wrong conclusions. KW - X-ray tomography KW - Silica KW - Styrene butadiene rubber KW - Dispersion PY - 2012 DO - https://doi.org/10.1016/j.jnoncrysol.2011.10.009 SN - 0022-3093 VL - 358 IS - 3 SP - 557 EP - 563 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-26105 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Staude, Andreas A1 - Bartscher, M. A1 - Ehrig, Karsten A1 - Goebbels, Jürgen A1 - Koch, M. A1 - Neuschaefer-Rube, U. A1 - Nötel, Jörg T1 - Quantification of the capability of micro-CT to detect defects in castings using a new test piece and a voxel-based comparison method JF - NDT & E international N2 - We present a modified aluminium casting which is especially suited as test piece for measuring casting defects and the geometry by means of cone-beam micro-focus X-ray systems, and which may become a reference standard for dimensional measurements and defect detection. To obtain a test piece with inner geometries measured by tactile means, we divided a small aluminium cylinder head into four pieces in such a way that most inner surfaces can be reached with a tactile probe. Reference geometries (spheres and cylinders) were applied to define a coordinate system for aligning the measurements in the disassembled and re-assembled state. The four pieces were re-assembled after the tactile measurement. The test piece also contains casting defects. In order to be able to use the assembled cylinder head as reference sample for defect detection, measurements with higher spatial resolution and better signal-to-noise ratio were performed on the single parts. For improving the reliability of the reference measurements, CT measurements of each part were carried out in three different orientations, and the individual defect detections were combined to obtain a reference data set with a high probability of defect detection and a low rate of erroneous detections. A new method for comparing the defect detection in a CT measurement to a reference data set is demonstrated, which provides individual information on every detected flaw. We discuss the results of measurements in the assembled state with respect to the reference data for flaw detection. KW - X-ray tomography KW - Casting KW - Defects KW - Porosity PY - 2011 DO - https://doi.org/10.1016/j.ndteint.2011.05.006 SN - 0963-8695 VL - 44 IS - 6 SP - 531 EP - 536 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-24028 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -