Analysis of Steel Fibers Distribution and Orientation in Hybrid-Fibers Reinforced High-Performance Concrete Column Using Micro-Computed Tomography

Abstract

High-performance concrete (HPC) offers better structural engineering properties such as higher compressive and tensile strength, enhanced durability, and better stiffness, compared to conventional normal concrete. However, a marked increase in the use of HPC has led to concerns regarding its brittle fracture characteristics and spalling under high temperature. Reinforcing HPC using hybrid-fibers (steel fibers + polypropylene fibers) is a popular method for reducing explosive fracture due to spalling and improving the mechanical properties of HPC. The performance of hybrid-fiber reinforced HPC concrete (HFRHPC) is determined by the fibers’ distribution and orientation within the concrete, which has been analyzed by optical and tomographic methods in previous studies. However, most of analyses were conducted on specimens that were produced in a laboratory. In this study, the distribution and orientation of the internal steel fibers of specimens extracted from an actual HFRHPC column were analyzed by micro-computed tomography (micro-CT). A total of nine core specimens were extracted according to the column’s height and distance from the mold. By using micro-CT, we visualized the distribution of steel fibers in the HFRHPC specimen. Moreover, the direction vector, scale, center position, volume, and surface area of the steel fibers in HFRHPC were successfully calculated