Spatial distribution of synthetic fibers in concrete with X-ray computed tomography

The strength and toughness prediction models for fiber-reinforced concrete (FRC) typically assume the spatial distribution of fibers is uniform. However, non-uniform dispersion can greatly affect the FRC's mechanical properties. Several techniques have been used in the past to quantify the distribution and orientation of steel fibers within concrete. For quantifying dispersion of synthetic fibers within concrete, a non-destructive technique using X-ray computed tomography (CT) combined with a post-processing image analysis is proposed. Due to X-ray attenuation similarities, the synthetic fibers were resolved from air voids by shape and size-based filters. The described approach to determine the actual fiber content within FRC samples was verified to be accurate. The method can be used to determine the individual fiber spatial distribution inside the concrete. As expected, the actual volume fraction of fibers in a fracture sample was correlated with the measured total fracture energy of the sample.