Evaluation of orientation and distribution of steel fibers in high-performance concrete column determined via micro-computed tomography

Abstract

This study investigated the orientation and distribution of steel fibers within high-performance concrete (HPC) column via micro-computed tomography (micro-CT) scanning. A real-scale HPC column was manufactured, and nine core specimens were extracted from the column according to the height of the column and distance from the mold. Cylindrical core specimens 70 mm in diameter and 70 mm high were prepared, and the orientation and distribution of fibers in the specimens were quantified via micro-CT. The moment of inertia for each steel fiber was determined to calculate the direction vector, scale, volume fraction, and surface area. We found that the steel fibers were typically oriented perpendicular to the main axis, which was in the direction of main vertical reinforcement steel embedded in the HPC column. Steel fibers nearest to the mold particularly showed the most perpendicular tendency. Results of the distribution showed that most of the steel fibers appeared at the bottom of the column and farthest from the mold. Therefore, as there exists a risk that stress can be concentrated to certain locations in the column, particular care and maintenance should be exercised.