Bond between Reinforcement and Steel Fibre–Reinforced Concrete: A Critical Review

Abstract

Conventional concrete is a common building material, weak in tension, often ridden with cracks due to its brittleness. However, it has low tensile and shear strength, as well as brittleness at failure. Concrete must be strengthened with suitable materials. Steel fibres are one of the most commonly used materials in the production of reinforced concrete, and it can partially or fully replace traditional steel reinforcement. The bond characteristics between the reinforcing fibres and the matrix are crucial for the effective reinforcement of concrete composites. As the load transfer from reinforcement bars to concrete depends on the bond formation, it is one of the most fundamental aspects of structural behaviour. The quality of bond has a significant impact on the crack development and the spacing amongst the length and width of cracks. The proper application of steel fibre reinforced concrete (SFRC) necessitates a thorough understanding of tensile behaviour's bonding mechanisms. As a consequence of this demand, this study offers the most comprehensive review of the main mechanisms controlling the bond strength between both the concrete and reinforced bars in SFRC composites that has been reported to date. The first part looked into the effects of various physical parameters of steel fibre such as geometry, inclination angle, embedded length, diameter, tensile strength on the fresh and hardened properties of SFRC, and matrix strength regulates steel fibre pull-out behaviour. The evaluation of the bond mechanisms of various types of steel fibres and steel bars in reinforced concrete (RC) components is the subject of the second section. This study also revealed how the fibre shape influences the bond action between the steel bars and matrix owing to the relative strengths of the various concrete. The bond strength theory, as well as the parameters that go along with it, active and passive confinement were cleared. Finally, recommendations for further study will be made. As a conclusion, steel fibres in concrete composites have been shown to improve the mechanical properties of concrete in general, particularly tensile strength, flexural strength, and bond strength. Furthermore, the addition of steel fibres to RC improves the bond between steel bars and the SFRC matrix. On the other hand, steel fibres have been shown to have detrimental effects on specific concrete properties, such as workability, which is decreased as the dosage of steel fibres is increased.