Hybridization of Steel Fibers with Different Geometry with PE Fibers For Better Tensile Performance of Ultra-High-Performance Fiber-Reinforced Concrete

Abstract

This study examined the effect of hybridization of steel and polyethylene (PE) fibers with different geometrical properties on the tensile performance of ultra-high performance fiber-reinforced concrete (UHPFRC). For this, three types of steel fibers including two different lengths of straight steel fibers and twisted steel fiber were hybridized with PE fibers. The total volume content of fibers was fixed at 2% and hybridization ratios were controlled as 0, 0.5, 1.0, 1.5, and 2.0%. The test results showed that steel fibers generally led to a higher tensile strength than PE fibers, but the PE fibers significantly improved strain capacity especially in hybrid fiber-reinforced specimens. Hybridizing these two types of fibers had a considerable positive effect on the compatibility of high strength and high strain capacity and led to a greater energy absorption capacity of the specimens. In terms of strain capacity and energy absorption capacity, hybridized fibers showed enormously better performance as compared to when they were singly used. Based on microscopic image analysis, it was found that damage types to the matrix around fibers were different depending on fiber type.