Abstract
In this study, the flexural behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) is examined as a function of fiber length and volume fraction. Straight steel fiber with three different lengths (lf) of 13, 19.5, and 30 mm and four different volume fractions (vf) of 0.5%, 1.0%, 1.5%, and 2.0% are considered. Test results show that post-cracking flexural properties of UHPFRC, such as flexural strength, deflection capacity, toughness, and cracking behavior, improve with increasing fiber length and volume fraction, while first-cracking properties are not significantly influenced by fiber length and volume fraction. A 0.5 vol % reduction of steel fiber content relative to commercial UHPFRC can be achieved without deterioration of flexural performance by replacing short fibers (lf of 13 mm) with longer fibers (lf of 19.5 mm and 30 mm).
Highlights
The brittleness and low strength-to-weight ratio of ordinary concrete are critical drawbacks limiting its practical application in structures subjected to tension or flexure
This study investigates the flexural properties of ultra-high-performance fiber-reinforced concrete (UHPFRC) with several fiber lengths and volume fractions
The flexural performance of UHPFRC with short straight steel fibers can be improved by increasing the fiber length
Summary
The brittleness and low strength-to-weight ratio of ordinary concrete are critical drawbacks limiting its practical application in structures subjected to tension or flexure. Wille et al [13] reported a UHPFRC with a relatively high tensile strength and ductility, made using deformed (end-hooked or twisted) fibers at a low fiber volume fraction. They [13] found that the post-cracking strain capacity (εpc = 0.6%) of a UHPFRC with. UHPFRC after replacing short fibers with long fibers while keeping the volume fraction constant (vf = 2.0%) Their studies [8,9] focused on improving the flexural performance of UHPFRC by changing the fiber length; based on their results alone, it is not straightforward to quantitatively determine how much increasing the fiber length will allow the volume fraction to be reduced in order to maintain the same performance.
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