Frequency-dependant dielectric parameters of steel fiber reinforced concrete

Steel Fiber Reinforced Concrete (SFRC) is increasingly being used in civil constructions, especially precast tunnel segment linings. Fibers are mixed with fresh concrete, which results in a more or less random distribution of fibers within the concrete matrix. Because of this, SFRC demonstrates a great challenge when it is being investigated using GPR. In order to investigate the frequency-dependent dielectric parameters of SFRC; (I) PET/CT scans of concrete were conducted to understand the nature of orientation and density of fibers being distributed within the concrete sample and (Π) a two-port coaxial transmission line technique developed for the determination of dielectric spectra of undisturbed soil samples was used to investigate the concrete's complex permittivity with and without steel fibers in the frequency range from 1 MHz to 5 GHz.