Mechanical Properties of Ultra-High Performance Fiber-Reinforced Concrete With Different Types of Steel Fiber

Abstract

The article examines the influence of steel fiber type and volumetric content on the mechanical properties of UHPFRC. Five fiber types were used: corrugated 15/0.3 and 22/0.3 mm, straight 13/0.3 and 13/0.2 mm, and hooked-end 30/0.5 mm. The fiber volume content ranged from 0 to 3%. During the experimental studies, compressive strength, flexural strength, as well as the flexural fracture energy were determined. It has been discovered that an increase in the volumetric content of steel fiber results in an enhancement of all the properties under consideration, irrespective of the type of fiber. The fiber has the biggest effect on the bending fracture energy and the least on the compressive strength. Linear relationships between the mechanical characteristics of UHPFRC and the fiber factor were established, which reflects the volumetric content, length, and diameter of an individual fiber. The slope angle of the approximating lines of the “compressive strength-fiber factor” and “flexural strength-fiber factor” relationships takes on different values depending on the type of fiber used. The highest slope angle is found for corrugated fiber. It was discovered that there is a threshold value of the fiber factor, upon reaching which the steel fiber leads to an increase in the flexural strength of the UHPFRC. According to a generalized quality criterion it has been determined that corrugated fiber with dimensions of 22/0.3 mm is the optimal substitute for straight fiber 13/0.2 mm, which is widely utilized for the production of Ultra-High Performance Fiber-Reinforced Concrete