TY - JOUR A1 - Ebell, Gino A1 - Burkert, Andreas A1 - Fischer, Joachim A1 - Lehmann, Jens A1 - Müller, Thoralf A1 - Meinel, Dietmar A1 - Paetsch, O. T1 - Investigation of chloride-induced pitting corrosion of steel in concrete with innovative methods JF - Materials and Corrosion N2 - The combination of electrochemical and 3D computed tomography (CT) investigations offers the possibility of verifying electrochemical measurements non-destructively. Determining the steel surfaces damaged by pitting corrosion allows developing specimens having damage pattern corresponding to practice. Corrosion phenomena like decoupled pitting corrosion cannot be verified by electrochemical measurements only, but with the combination of those two kinds of investigations it is possible. Another advantage is the minimization of the number of samples. The classical experimental procedure requires the destruction of samples after each damage step.This can be avoided by the use of 3D computed tomography. As long as the corrosion phenomena are completely within the examination zone shown by the 3D computed tomography, the electrochemical measurements can be calculated on an area basis to get the specific corrosion rate or polarization resistance. KW - Corrosion KW - Concrete KW - 3D x-ray KW - Corrosion rate PY - 2016 DO - https://doi.org/10.1002/maco.201608969 SN - 1521-4176 SN - 0947-5117 SN - 0043-2822 VL - 67 IS - 6 SP - 583 EP - 590 PB - Wiley-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-36341 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meinel, Dietmar A1 - Ehrig, Karsten A1 - L'Hostis, V. A1 - Muzeau, B. A1 - Paetsch, O. T1 - Examination of damage processes in concrete with CT T2 - Conference on industrial computed tomography (ICT) 2014 (Proceedings) N2 - In order to extend the lifetime of buildings and constructions at the macro scale it is necessary to understand the damage processes of building materials at the micro scale. In particular, durability of reinforced concrete structures is one of the most important equirements for construction planning and restoration of buildings. Therefore degradation mechanisms were reproduced on laboratory specimens. CT (Computed Tomography) is commonly used for non-destructive microstructural defect analysis for recurring tests on concrete specimens. In this work a few examples of CT applications on cementitious materials (including cement paste, mortar and concrete specimens) will be presented. Firstly, in order to quantify the degradation processes, specimens analysed were damaged by corrosion due to carbonation and due to chloride ingress. Particular focus has been set to the analysis of cracks. An automated crack detection tool, developed by Zuse Institut Berlin (ZIB) and BAM in ZIBAmira, has been applied for quantitative analysis of crack parameters and 3D visualization of cracks. Furthermore the distribution of corrosion products has been evaluated inside the cement matrix and visualized in 3D data sets. Another important factor for the ageing stability of concrete is the interfacial transition zone (ITZ). The ITZ consists of a layer of cement paste (20 to 40 μm) over every aggregate where porosity is generally increased in comparison with the bulk. This zone could be a preferential zone for transfer of aggressive species. To visualize the ITZ, a small sample of mortar with a diameter of 10mm has been prepared and scanned using the industrial μCT setup at BAM with a spatial resolution of 5μm voxel size. In addition the extracted surface of aggregates could be used for load simulations. We finally show how CT examination of drilled samples taken from building materials in conjunction with laboratory experiments is helpful for further evaluations of damage processes in concrete. T2 - Conference on industrial computed tomography (ICT) 2014 CY - Wels, Austria DA - 25.02.2014 KW - X-ray computed tomography KW - Concrete KW - Corrosion KW - Crack detection KW - 3D visualization PY - 2014 SN - 978-3-8440-2557-6 SN - 1610-4773 SP - 111 EP - 122 PB - Shaker Verlag GmbH AN - OPUS4-30332 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Paetsch, O. A1 - Baum, D. A1 - Prohaska, S. A1 - Ehrig, Karsten A1 - Meinel, Dietmar A1 - Ebell, Gino T1 - 3D corrosion detection in time-dependent CT images of concrete T2 - DIR 2015 - International symposium on digital industrial radiology and computed tomography N2 - In civil engineering, the corrosion of steel reinforcements in structural elements of concrete bares a risk of stability-reduction, mainly caused by the exposure to chlorides. 3D computed tomography (CT) reveals the inner structure of concrete and allows one to investigate the corrosion with non-destructive testing methods. To carry out such investigations, specimens with a large artificial crack and an embedded steel rebar have been manufactured. 3D CT images of those specimens were acquired in the original state. Subsequently three cycles of electrochemical pre-damaging together with CT imaging were applied. These time series have been evaluated by means of image processing algorithms to segment and quantify the corrosion products. Visualization of the results supports the understanding of how corrosion propagates into cracks and pores. Furthermore, pitting of structural elements can be seen without dismantling. In this work, several image processing and visualization techniques are presented that have turned out to be particularly effective for the visualization and segmentation of corrosion products. Their combination to a workflow for corrosion analysis is the main contribution of this work. T2 - DIR 2015 - International symposium on digital industrial radiology and computed tomography CY - Ghent, Belgium DA - 22.06.2015 KW - Concrete KW - Corrosion detection KW - 3D computer tomography (CT) imaging KW - Image processing KW - Visualization PY - 2015 SP - 1 EP - 10 AN - OPUS4-33711 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -