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Description
This study presents a robust and comprehensive comparison between two methodologies for evaluating the orientation and spatial distribution of steel fibers in fiber-reinforced concrete (FRC): computed tomography (CT) and the inductive method (IM). Both techniques were applied to cylindrical cores extracted from large-scale structural elements, enabling a direct comparison of their results.
CT scanning, combined with advanced image post-processing software, allowed for the 3D reconstruction of all fibers within the specimens, providing individual information on fiber position, volume, and orientation. In contrast, the inductive method—based on changes in magnetic impedance caused by the presence of steel fibers—offered average values for fiber content and orientation in each sample. The comparison of IM results against CT data revealed a high degree of agreement in the estimation of fiber volume and orientation.
To further validate the inductive method, an additional experimental campaign was conducted using hand-crafted cylinders with known fiber content and orientation. The results confirmed the method’s accuracy, with errors below 15% in all cases, supporting its reliability and robustness.
While CT scanning provides a more complete dataset—including potential insights into porosity, cracking, and aggregate distribution—it is limited by higher costs, longer processing times, and more complex equipment requirements. On the other hand, the inductive method, when properly calibrated, stands out as a faster and more cost-effective alternative for quality control, as long as ferromagnetic fibers are used.
Finally, a preliminary application of dual-energy CT (DECT) was explored to assess its potential in FRC research. Although the initial results were promising, further studies are recommended to extend the analysis to the entire specimen volume in order to better understand the relevance of DECT parameters in relation to fiber distribution.
