Interpretation and analysis of scattering in steel fiber alignment in concrete: The H alpha decomposition method using fully polarized B-scan ground penetrating radar (GPR) image data

Abstract

The brittle behavior of concrete often necessitates fiber reinforcement to improve load distribution and crack resistance. This study examines fiber orientation in steel fiber-reinforced concrete, achieved by strategically aligning fibers within the fresh composite. B-scan Ground Penetrating Radar (GPR) with full polarimetric imaging is utilized for non-destructive assessment of fiber alignment in the concrete matrix. Using two horn antennas, measurements are taken at two cm intervals along a 120 cm synthetic aperture at 101 different locations in the 2–6 GHz frequency band in horizontal-horizontal (HH), vertical-vertical (VV), horizontal-vertical (HV), and vertical-horizontal (VH) polarizations. These measurements, made at frequencies between 2 and 6 GHz across a range of polarizations, enabled two-dimensional imaging using both H-alpha polarimetric decomposition and raw data images. These imaging methods are used in combination with H-alpha classification surfaces separated into different scattering regions and raw S₂₂ and S₂₁ 2D images to obtain the expected results. Results indicate that concrete samples with random, horizontal, and vertical fiber orientations exhibit distinct scattering patterns, enabling accurate identification of internal fiber configurations. The scattering analysis confirmed the precision of alignment determination, demonstrating a reliable, non-destructive method for evaluating fiber orientation in reinforced concrete. This approach holds substantial promise for quality assurance and performance assessment in fiber-reinforced concrete production.