TY - CHAP A1 - Oesch, Tyler A1 - Stenzel, Ludwig A1 - Weise, Frank T1 - Non-destructive Evaluation of the Contribution of Polymer-Fibre Orientation and Distribution Characteristics to Concrete Performance during Fire T2 - Short Fibre Reinforced Cementitious Composites and Ceramics N2 - Although concrete itself is not a combustible material, concrete mixtures with high density, such has high-performance concretes (HPCs), are susceptible to significant damage during fires due to explosive spalling. Past research has shown that the inclusion ofpolymer fibres in high density concrete can significantly mitigate this fire damage. The exact mechanisms causing this increased spalling resistance are not yet fully understood, but it is thought that the fibres facilitate moisture transport during fire exposure, which in turn contributes to relief of internal stresses in the spalling-susceptible region. In this study, X-ray Computed Tomography (CT) was applied to observe the interaction between polymer fibres and cracking during thermal exposure. For this purpose, two concrete samples containing different polymer fibre types were subjected to incremental application of a defined thermal exposure. CT images were acquired before and after each thermal exposure and powerful image processing tools were used to segment the various material components. This enabled a detailed analysis of crack formation and propagation as well as the visualization and quantification of polymer fibre characteristics within the concrete. The results demonstrated that the orientation of both fibres and cracks in polymerfibre reinforced concrete tend to be anisotropic. The results also indicated that crack geometry characteristics may be correlated with fibre orientation, with cracks tending to run parallel to fibre beds. Clear quantitative relationships were also observed between heating and increasing cracking levels, expressed in terms of both crack surface area and crack volume. KW - Concrete KW - Fire resistance KW - Polymer fibre PY - 2019 SN - 978-3-030-00867-3 DO - https://doi.org/10.1007/978-3-030-00868-0_4 VL - 95 SP - 51 EP - 73 PB - Springer Nature Switzerland AG CY - Zürich AN - OPUS4-51077 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stelzner, Ludwig A1 - Weise, Frank A1 - Oesch, Tyler A1 - Dlugosch, R. A1 - Powierza, Bartosz T1 - Transport and reconfiguration of moisture in HPC due to unilateral heating T2 - Proceedings of the 6th International Workshop on Concrete Spalling due to Fire Exposure N2 - Explosive spalling is caused by, among others, the thermohydraulic spalling mechanism. During this process, vaporization, dehydration, moisture-transport and condensation processes interact. As a result, a drying and dehydration zone as well as a saturated zone, known as a moisture clog, are observed inside the unilaterally-heated concrete. The presented research is focused on the experimental investigation of the underlying thermohydraulic processes. To investigate these, a test methodology based on X-ray computed tomography (CT) and nuclear magnetic resonance (NMR) was developed. Thereby, the X-ray CT scans are carried out simultaneously during the application of a defined unilateral-heating regime on a specially-constructed specimen. This miniaturized specimen, equipped with a double-layer casing, reproduces the condition within a planar, unilaterally-heated building component. A preliminary test methodology and the first experimental results were presented at the 5th International Workshop on Concrete Spalling in Borås, Sweden (2017). The contribution for the upcoming workshop presents an improved version of this test methodology and new results for a high-performance concrete (HPC) mixture exposed to temperatures up to 500 °C. Regarding the CT measurements, a higher time-resolution of 15 min was achieved and a quantification of the moisture changes was implemented. Due to an increase in signal quality of the NMR measurements, a pore-size specific moisture distribution can now be resolved. This allows to conclude about the moisture reconfiguration between small gel pores and larger interhydrate pores. Additionally, the NMR measurement are no longer limited to first 2.5 cm below the heated surface but a one-dimensional moisture distribution can now be estimated over the whole 10 cm long specimen. The presented results demonstrate that the combination of X-ray CT and NMR measurements enables to image and quantify the thermally-induced moisture transport and reconfiguration from small gel pores up to macro pores. This provides important insights into the thermohydraulic damage mechanism and leads to a better understanding of spalling avoidance strategies, like the addition of polypropylene fibres. T2 - 6th International Workshop on Concrete Spalling due to fire exposure CY - Sheffield, UK DA - 19.09.2019 KW - Moisture clog KW - X-ray CT KW - NMR KW - Moisture transport KW - HPC PY - 2019 UR - https://firespallingworkshop2019.group.shef.ac.uk/wp-content/uploads/2019/09/Fire-Spalling-Workshop_Proceedings.pdf SN - 978-1-5272-4135-0 SP - 181 EP - 190 CY - Sheffield AN - OPUS4-49161 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stelzner, Ludwig A1 - Powierza, Bartosz A1 - Oesch, Tyler A1 - Dlugosch, R. A1 - Weise, Frank T1 - Thermally-induced moisture transport in high-performance concrete studied by X-ray-CT and 1H-NMR JF - Construction and Building Materials N2 - The thermohydraulic damage mechanism is one of the primary causes for explosive spalling of highperformance concrete. This paper presents the spatially- and temporally-resolved analysis of the thermally-induced moisture transport and reconfiguration processes by means of X-ray-CT and 1HNMR. Thermal testing results for a high-performance concrete, which is sensitive to explosive spalling and which was prepared with and without added polypropylene fibres, are presented in this paper. These results indicate that the addition of fibres leads to a faster and deeper migration of the drying front and, thus, to a lower likelihood of vapour-pressure induced explosive spalling. KW - Explosive spalling KW - Thermally-induced moisture transport KW - X-ray-CT KW - 1H-NMR KW - High-performance concrete PY - 2019 DO - https://doi.org/10.1016/j.conbuildmat.2019.07.065 SN - 0950-0618 VL - 224 SP - 600 EP - 609 PB - Elsevier Ltd. AN - OPUS4-48727 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Powierza, Bartosz A1 - Stelzner, Ludwig A1 - Oesch, Tyler A1 - Gollwitzer, Christian A1 - Weise, Frank A1 - Bruno, Giovanni T1 - Water migration in one-side heated concrete: 4D in-situ CT monitoring of the moisture-clog-effect JF - Journal of Nondestructive Evaluation N2 - Explosive spalling due to fire exposure in concrete structures can lead severe damage and, in the worst case, to premature component failure. For this reason, an in situ investigation of water Migration in concrete due to surface heating was undertaken. During these experiments, a miniaturized concrete specimen within a confining and insulating double-hull was subjected to surface heating during simultaneous X-ray computed tomography (CT) scanning. Through the use of subtraction-based Image analysis techniques, it was possible to observe and quantify not only drying within areas of the concrete matrix close to the heated surface, but also the migration of moisture to both pore and matrix regions deeper within the specimen. It was also discovered that the correction of CT images for specimen deformation using DVC and variable detector performance using calibrated image filters significantly improved the quality of the results. This clearly demonstrates the potential of X-ray CT for evaluation of other rapid-density-change phenomena in concrete and other building materials. T2 - 8th Conference on Industrial Computed Tomography (iCT 2018) CY - Wels, Austria DA - 06.02.2018 KW - In-Situ X-ray CT KW - Digital Volume Correlation KW - Heated concrete KW - Water migration KW - Fire PY - 2019 DO - https://doi.org/10.1007/s10921-018-0552-7 SN - 1573-4862 SN - 0195-9298 VL - 38 IS - 1 SP - 15, 1 EP - 11 PB - Springer US CY - New York / Heidelberg AN - OPUS4-47147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Oesch, Tyler A1 - Stelzner, Ludwig A1 - Weise, Frank ED - Herrmann, H. ED - Schnell, J. T1 - Non-destructive evaluation of the contribution of polymer-fibre orientation and distribution characteristics to concrete performance during fire T2 - Short Fibre Reinforced Cementitious Composites and Ceramics N2 - Although concrete itself is not a combustible material, concrete mixtures with high density, such has high-performance concretes (HPCs), are susceptible to significant damage during fires due to explosive spalling. Past research has shown that the inclusion of polymer fibres in high density concrete can significantly mitigate this fire damage. The exact mechanisms causing this increased spalling resistance are not yet fully under-stood, but it is thought that the fibres facilitate moisture transport during fire exposure, which in turn contributes to relief of internal stresses in the spalling-susceptible region. In this study, X-ray Computed Tomography (CT) was applied to observe the interaction between polymer fibres and cracking during thermal exposure. For this purpose, two concrete samples containing different polymer fibre types were subjected to incremental application of a defined thermal exposure. CT images were acquired before and after each thermal exposure and powerful image processing tools were used to segment the various material components. This enabled a detailed analysis of crack formation and propagation as well as the visualization and quantification of polymer fibre characteristics within the concrete. The results demonstrated that the orientation of both fibres and cracks in polymer-fibre reinforced concrete tend to be anisotropic. The results also indicated that crack geometry characteristics may be correlated with fibre orientation, with cracks tending to run parallel to fibre beds. Clear quantitative relationships were also observed between heating and increasing cracking levels, expressed in terms of both crack surface area and crack volume. KW - X-ray Computed Tomography (CT) KW - Polypropylene Fibres KW - Fire Performance KW - Fibre-Reinforced Concrete (FRC) KW - Fibre Orientation Analysis PY - 2019 SN - 978-3-030-00868-0 DO - https://doi.org/10.1007/978-3-030-00868-0 SP - 51 EP - 73 PB - Springer Nature Switzerland AG AN - OPUS4-47206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oesch, Tyler A1 - Weise, Frank A1 - Meinel, Dietmar A1 - Gollwitzer, Christian T1 - Quantitative in-situ analysis of water transport in concrete completed using X-ray computed tomography JF - Transport in Porous Media N2 - This paper describes a novel methodology for quantitative in-situ moisture measurement without tracking agents using X-ray computed tomography (XCT). The high levels of grey-scale precision required for the measurement of moisture without tracking agents resulted in the need for an additional image calibration procedure to correct for water-related X-ray scattering and for equipment-variability related artefacts arising during in-situ testing. This calibration procedure was developed on the basis of existing principles of XCT image cor-rection. Resulting images of moisture distribution exhibit a high level of agreement with expected material behaviour. This research demonstrated that XCT can be successfully used to measure both moisture-front movement over time and changes in 3D moisture distribution within samples. This approach to moisture measurement lays the groundwork for the planned future investigation of the interaction between cracking induced by varying chemical and mechanical processes and water transport in concrete. KW - X-ray computed tomography (XCT) KW - In-situ testing KW - Water transport KW - Quantitative moisture measurement KW - Concrete PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474395 DO - https://doi.org/10.1007/s11242-018-1197-9 SN - 1573-1634 VL - 127 IS - 2 SP - 371 EP - 389 PB - Springer Netherlands AN - OPUS4-47439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -