Experimental Investigation on the Mechanical and Durability Properties of Fiber-Reinforced Concrete with Varying Fiber Content

Abstract

Steel fiber-reinforced concrete (SFRC) appears as one of the promising construction material, as it exhibits better mechanical properties, crack resistance and durability to conventional concrete. The current study aims to explore how the fresh and hardened characteristics of M30 grade of concrete change with different steel fiber contents. A series of six concrete mixtures - one control mixture (CM) and five mixtures with 0.25%, 0.50%, 0.75%, 1.00% and 1.25% steel fibers - were prepared. The water/cement ratio was kept constant (0.45) for all the mixes. Slump tests were conducted to assess the workability, and compressive strength tests, split tensile strength tests and flexural strength tests were also performed to assess the strength of the material, after 7 and 28 days. It was found that adding the steel fibers greatly affected the characteristics of concrete. As the fiber content increased, the workability of the mix started to drop and the slump dropped from 85 mm (control mix) to 45 mm (when 1.25% steel fiber was used in the mix). Significant gains were, however, noticed in the mechanical properties. At 28-days, the optimum compressive, flexural and split tensile strengths were respectively 50.3, 8.10 and 5.05MPa, which was produced from the mix with the proportion of steel fibers of 1.00%. A slight loss of strength was noted above this amount because of the decrease in workability and clustering of fibres. The study results revealed that the incorporation of steel fiber can effectively improve the strength properties of concrete, with an optimum value of about 1.00% vol of steel fiber as the best trade-off between workability and mechanical properties. The results show that SFRC can be used in the fields of structural applications that demand better crack resisting, ductile and load carrying capacity.