Mechanical Properties of Ultra-High-Performance Fiber-Reinforced Concrete Containing Synthetic and Mineral Fibers

This study investigated the effects of different synthetic and mineral fibers and limestone powder on the mechanical properties of ultra-high-performance fiber-reinforced concrete (UHPFRC). For the purpose of this study, 16 mixture designs and 204 prism specimens were prepared and cured under either of wet or autoclave conditions. Measurements revealed that mixtures containing synthetic fibers recorded considerable compressive and flexural strengths close to the steel fiber-reinforced mixtures. Specimens reinforced with nylon fibers as the best fibers in this study exhibited a much better flexural performance in terms of flexural strength, deflection capacity, and post-peak ductility than did those containing ceramic and polyester fibers. Finally, specimens containing limestone powder recorded acceptable flexural strength, which was close to those only containing silica fume. The X-ray diffraction (XRD) test showed that limestone powder increased ettringite content due to the dilution effect at 180 days as the main reason for decreasing of compressive strength of mixtures.