Properties and Development of Steel Fiber Reinforced Concrete

Steel fiber reinforced concrete (SFRC) is a new type of composite material that can be casted and sprayed up by mixing an appropriate amount of short steel fiber to normal concrete. In recent years SFRC has developed rapidly at home and abroad.

1.The properties of steel fiber reinforced concrete

Compared with normal concrete, steel fiber reinforced concrete has far better resistance to tensile, shear, bending, abrasion and crack, and its fracture toughness and impact resistance also have been greatly enhanced, which lead to better performance in fatigue resistance and durability of the structure in its adoption. It is to be noted that, the toughness of SFTC can be increased by 10 to 20 times. A comparative test on the mechanical properties of steel fiber reinforced concrete and normal concrete has been conducted in China. The result indicates that when the admixing quantity of steel fiber account for 15%-20% and the water-cement ratio is 0.45, the tensile strength will increase by 50% to 70%, and the bending strength will increase by 120% to 180%. At the same time, the impact strength will increase by 10 to 20 times, the impact fatigue strength will increase by 15 to 20 times and the flexural strength will also increase by 14 to 20 times. Also the improvement of wear resistance is remarkable. Therefore, it can be confirmed that steel fiber reinforced concrete has superior physical and mechanical properties than plain concrete.

2. The basic theory of steel fiber reinforced concrete

(1). The theory of compound mechanics. The theory of composite mechanics is based on the theory of continuous fiber composite materials, combined with the distribution characteristics of steel fibers in concrete. The theory regards the composite material as a two-phase composite material, with fiber as one phase and matrix as another.

(2). The theory of fiber spacing. The fiber spacing theory, also known as crack resistance theory, is based on linear elastic fracture mechanics. According to the theory, the reinforcement effect of fiber produced by concrete fiber suppliers is only related to the evenly distributed fiber spacing (minimum spacing).

3. The application of steel fiber reinforced concrete

Fiber reinforced concrete (FRC), especially steel fiber reinforced concrete (SFRC), due to its superior performance, has gain more and more attention in its adoption in practical engineering from the field of academic and engineering. Up to now, with the promotion of the adoption of steel fiber reinforced concrete, due to the different distribution of fibers in concrete, fiber reinforced concrete are mainly divided into four categories: steel fiber reinforced concrete, hybrid fiber reinforced concrete, layered steel fiber reinforced concrete and layered hybrid fiber reinforced concrete.

As a new type of composite material, steel fiber reinforced concrete (SFRC) is known for its excellent physical and mechanical properties, such as good tensile resistance, bending resistance, crack resistance, impact resistance, fatigue resistance, high toughness, etc. Now it has been chosen to used in a range of engineering projects including the professional areas of construction, water conservancy, highway tunnel, highway pavement and airport pavement, railway line, pipeline, inland waterway, riot, maintenance and reinforcement and so on.