Effect of Fibre Tensile Strength, Aspect Ratio and Volume Fraction on Rheological and Mechanical Properties of High-Strength Self-compacting Concrete

Evaluating the rheological and mechanical characteristics of self-compacting fibre-reinforced concrete is one of the challenges in structural engineering. In this paper, the influence of coarse aggregate content and steel fibre volume fraction including its aspect ratio and tensile strength on the rheological and fundamental mechanical properties of high-strength self-compacting concrete are investigated. For this purpose, hooked-end steel fibres 30 mm long with two different tensile strengths of 1345 and 3070 MPa and aspect ratios (l/d) of 55 and 80 were respectively used. The casting of all test specimens was carried out using a consistent water-to-cementitious materials ratio of 0.40, with the replacement of 40% of cement by ground granulated blast furnace slag (GGBS). The slump flow tests were conducted to assess the fresh properties of high-strength self-compacting concrete. In addition, the mechanical properties of hardened concrete were investigated using the compressive strength test, elastic modulus test, splitting tensile strength test, and three-point bending test. The test results revealed that the workability of high-strength self-compacting concrete is reduced as the volume fraction and aspect ratio of steel fibre increase. On the other hand, the splitting tensile strength and fracture energy are improved by increasing the volume fraction of fibre. It was noted that the fibre tensile strength and aspect ratio have a substantial effect on the fracture energy and post-peak behaviour.