Mechanical properties and postcracking behavior of self-compacting fiber reinforced concrete

Fiber reinforced concrete is widely used due to its high ductility, energy absorbing capacity, and tensile strength. In this study, the effects of fibers on fresh concrete properties and mechanical properties of self-compacting fiber reinforced concrete (SFRC) were investigated. Basalt fiber (BF), glass fiber (GF), and polypropylene fiber (PPF) were added to the concrete mixtures at the ratios of 0.15, 0.20, 0.25, and 0.30% by volume. The impacts of the content and type of fiber on the fresh SFRC properties (slump-flow diameter, V-funnel flow time, and blocking rate) and mechanical properties such as compressive strength, flexural strength, splitting tensile strength, and toughness index were analyzed. In addition, the microstructure among cement paste and fibers were investigated using scanning electron microscope images. The results show that the adding of fiber to the mixtures significantly improved the flexural and tensile strength, whereas no significant change in compressive strength was observed. In addition, toughness, which is an important parameter for SFRC, was also determined according to ASTM C 1609. None of the BF and GF specimens reached the intended deflection of L/150 (L is the span). A rapid decrease in load was observed after peak load in both fiber types and the samples showed a brittle fracture. On the contrary, the PPF series showed markedly different postcracking behavior than the BF and GF. Compared with the plain concrete, T-L/150 of SFRC with BF, GF, and PPF increase by 29-54%, 17-36%, 133-172%, respectively.