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 - JOUR A1 - Poyet, S. A1 - Dridi, W. A1 - L'Hostis, V. A1 - Meinel, Dietmar T1 - Microstructure and diffusion coefficient of an old corrosion product layer and impact on steel rebar corrosion in carbonated concrete JF - Corrosion Science N2 - Corrosion is the major degradation pathway affecting reinforced concrete structures. In the long-term, the rust layer might become thick and slow down the diffusion of oxygen from the atmosphere to the steel. With this in mind, the mineralogy, microstructure and diffusion properties of an old and thick corrosion product layer were investigated. Despite the presence of macropores, the gas diffusion coefficient was found to be low. The impact of the layer on the oxygen diffusion was evaluated using Fick’s law. The results showed that the layer could reduce the flux of oxygen only in a specific configuration. KW - Steel reinforced concrete KW - Rust KW - X-ray computed tomography KW - Micro-CT PY - 2017 DO - https://doi.org/10.1016/j.corsci.2017.06.002 VL - 2017 IS - 125 SP - 48 EP - 58 PB - Elsevier B.V. CY - Radarweg 29, 1043 NX Amsterdam, The Netherlands AN - OPUS4-41784 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -