Fiber-Distribution Assessment in Steel Fiber–Reinforced UHPC Using Conventional Imaging, X-Ray CT Scan, and Concrete Electrical Conductivity

Abstract

Specimens were made of ultrahigh-performance concrete (UHPC) with two ratios of sand to cementitious materials, 0.5 and 1.25. Specimens with 0%, 0.5%, 1%, 1.5%, and 2% fiber content were prepared from each mixture. Fiber distribution in these specimens was investigated using three techniques: conventional imaging, X-ray computed tomography scanning (CT scan), and electrical conductivity. All techniques were able to determine the fiber distribution in UHPC. However, the electrical conductivity measurements required minimum preparation and were less expensive and faster compared to the other techniques. It was found that increasing the ratio of sand to cementitious material in the mixture decreased flowability and the fibers tended to settle down in a mixture with higher flowability compared to the mixture with lower flowability.