Experimental relationships between steel fiber volume fraction and mechanical properties of ultra-high performance fiber-reinforced concrete

Adding steel fibers with a suitable dosage to the mix design of ultra-high performance concrete both impressively forms the concrete ductility, and improves the mechanical strength. In this study, an ultra-high performance fiber reinforced concrete (UHPFRC) mixture was designed with different percentages of steel fiber. Then, the effect of fiber percentage in this mix design was compared to the results of the other researches. Furthermore, Mechanical properties of UHPFRC were assessed, including compressive, splitting tensile, and flexural strength. The relationship of these mechanical properties to each other and also to the fiber percentage content were derived. Moreover, a conversion factor between the compressive strength of cubical to cylindrical samples was derived for different fiber percentages. According to the results, the inclusion of 3% straight steel fibers resulted in a maximum increase of 81%, 228% and 180% for compressive, splitting tensile, and flexural strength, respectively which yielded more significant results than other studies.