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1مؤتمر
مصطلحات موضوعية: Fiber reinforced concrete, pull-out behavior, X-ray Computed Tomography, Digital Volume Correlation, Infrastructure Engineering, Infrastrukturteknik
الوصف: Fiber pull-out is generally considered to be the dominating failure mechanism in fiber reinforced concrete (FRC). Accordingly, pull-out tests are typically performed to characterize the fiber-matrix interaction. However, little direct insight can be gained on the actual mechanisms ofthe pull-out from such a test. Deeper understanding could however be gained through the addition of non-destructive techniques to pull-out tests to enable the visualization and quantification of the mechanical interaction. Pull-out mechanisms for different common steel fibers were investigated using adapted pull-out tests performed in-situ in an X-ray micro tomography (µXRT). High resolution volume images from the µXRT scans enable clear visualization of aggregates, pores, fiber and fiber-matrix interface. Furthermore, the natural density speckle pattern from aggregate distribution and pores was found to be suitable for Digital Volume Correlation (DVC) analysis. From the DVC results it was possible to visualize and quantify the strain distribution in the matrix around the fiber at different load levels up to final failure, being marked by either pull-out or fiber rupture. The load transfer mechanism was initially dominated by shear along the fiber. As the load increased, slip occurred in the end-hook region and mechanical locking became the governing mechanism. This study demonstrates that strain measurements within the concrete matrix and passive end-slip can be obtained successfully using µXRT imaging and DVC analysis, which leads to an increased understanding of the interaction mechanisms in fiber reinforced concrete under mechanical loading.
وصف الملف: application/pdf
العلاقة: proc. of 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures (FraMCoS-X); orcid:0000-0002-3481-1368; orcid:0000-0002-0033-1841; http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-39953Test
الإتاحة: https://doi.org/10.21012/FC10.233198Test
http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-39953Test -
2مؤتمر
مصطلحات موضوعية: Fiber reinforced concrete, pull-out behavior, X-ray Computed Tomography, Digital Volume Correlation, Infrastructure Engineering, Infrastrukturteknik
الوصف: Pull-out mechanisms for different common steel fibers were investigatedusing adapted pull-out tests performed in-situ in an x-ray micro tomograph(µXRT). High-resolution volume images from the µXRT scans enable clearvisualization of aggregates, pores, the fiber and the fiber-matrix interface.Furthermore, the natural density speckle pattern from aggregate distributionand pores was found suitable for Digital Volume Correlation (DVC) analysis.From the DVC results it was possible to visualize and quantify the straindistribution in the matrix around the fiber at the different load levels up tofinal failure, being marked by either pull-out or fiber rupture. This studydemonstrates that strain measurements within the concrete matrix can beobtained successfully using µXRT imaging and DVC analysis, which leads to anincreased understanding of the interaction mechanisms in fibre reinforcedconcrete under mechanical loading.
وصف الملف: application/pdf
العلاقة: orcid:0000-0002-3481-1368; orcid:0000-0002-0033-1841; http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-35557Test
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3مؤتمر
المؤلفون: Sedighi Moghaddam, Maziar, Van den Bulcke, J., Wålinder, M. E. P., Claesson, Per M., Van Acker, J., Swerin, Agne
مصطلحات موضوعية: acetylation, furfurylation, microstructure, X-ray Computed Tomography, wettability, Wood Science, Trävetenskap, Physical Chemistry, Fysikalisk kemi, Analytical Chemistry, Analytisk kemi
الوصف: Mapping and visualization of structural changes due to the modification of wood would increase the understanding of chemical modification processes and facilitate optimization of the process parameters. The 2D and 3D microstructure of acetylated and furfurylated softwood and hardwood were visualized using X-ray computed tomography and some anatomical features were investigated such as total porosity, cell wall thickness and maximum opening of tracheid lumens. The wetting properties of chemically modified samples were related to the microstructural properties. Significant changes in the wood structure were observed for furfurylated sapwood samples mainly indicated by a change in tracheid shape and filling of tracheids by furan polymer, whereas no microstructural changes were noted for acetylated samples. Furfurylation significantly decreased the porosity of the sample in both earlywood and latewood regions; whereas for acetylated samples the total porosity of modified and unmodified samples was rather similar. This is in line with results of wetting showing that furfurylation reduced both swelling and capillary uptake in contrast to acetylation which reduced mostly swelling.
وصف الملف: application/pdf
العلاقة: orcid:0000-0002-2614-1245; orcid:0000-0002-6394-6990; http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-27781Test
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4دورية أكاديمية
المؤلفون: Röding, Magnus, Del Castillo, L. A., Nydén, M., Follink, B.
مصطلحات موضوعية: Microstructure, nanoporous, scanning electron microscopy, sintering, X-ray computed tomography, Physical Sciences, Fysik
الوصف: We study the microstructure of a granular amorphous silica ceramic material synthesized by spark plasma sintering. Using monodisperse spherical silica particles as precursor, spark plasma sintering yields a dense granular material with distinct granule boundaries. We use selective etching to obtain nanoscopic pores along the granule borders. We interrogate this highly interesting material structure by combining scanning electron microscopy, X-ray computed nanotomography and simulations based on random close packed spherical particles. We determine the degree of anisotropy caused by the uni-axial force applied during sintering, and our analysis shows that our synthesis method provides a means to avoid significant granule growth and to fabricate a material with well-controlled microstructure.
وصف الملف: application/pdf
العلاقة: Journal of Microscopy, 0022-2720, 2016, 264:3, s. 298-303; orcid:0000-0002-5956-9934; http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-27584Test; Scopus 2-s2.0-84977534321
الإتاحة: https://doi.org/10.1111/jmi.12442Test
http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-27584Test
