Mechanical performance of self-compacting concrete reinforced with steel fibers

• Workability of SCC decreases considerably by adding steel fibers.
• Compressive strength loss in HS-SCC class was lower than that of MS-SCC class.
• Flexural toughness enhances significantly when steel fibers were utilized.

Self-compacting concrete (SCC) is a highly-workable concrete that without any vibration or impact and under its own weight fills the formwork, and it also passes easily through small spaces between rebars. In this paper, the effect of steel fibers on rheological properties, compressive strength, splitting tensile strength, flexural strength, and flexural toughness of SCC specimens, using four different steel fiber volume fractions (0.5%, 1%, 1.5%, and 2%), were investigated. Two mix designs with strengths of 40 MPa (medium strength) and 60 MPa (high strength) were considered. Rheological properties were determined through slump flow time and diameter, L-box, and V-funnel flow time tests. Mechanical characteristics were obtained through compressive strength and splitting tensile strength tests with standard cylindrical specimens of 150 × 300 mm, and flexural strength and flexural toughness tests were performed by using beams of 100 × 140 × 1200 mm.The results revealed that the workability of medium and high strength SCC classes is reduced by increasing the steel fiber volume fraction, and using high percentages of fibers led to decrease of other rheological characteristics that have been specified by EFNARC and ACI 237R. On the contrary, splitting tensile strength, flexural strength, and flexural toughness are increased by increasing the percentage of fibers; however compressive strength is decreased by increasing the percentage of fibers.