Advantages and Disadvantages of Steel Fiber Concrete

Advantages of Steel Fiber Concrete:

1. The strength-to-weight ratio is increased. This is an important sign that steel fiber concrete has superior economic performance.

2. It has high tensile, bending, shear and torsion strength.

The tensile strength of steel fiber concrete is increased by 25% to 50%, the bending strength is increased by 40% to 80%, and the shear strength is increased by 50% to 100%. Steel fiber concrete can withstand large deformation of surrounding rock and soil and maintain good integrity due to its high tensile, bending and shear strength.

3. Excellent impact resistance
The performance of a material to resist impact or vibration loads is called impact toughness. The impact and compressive toughness of steel fiber concrete can be increased by 2 to 7 times, and the impact bending, tensile and other toughness can be increased by several times to dozens of times.

4. Significantly improved shrinkage performance. The shrinkage value of steel fiber concrete is reduced by 7% to 9% compared with ordinary concrete.

5. Significantly improved fatigue resistance
The bending and compressive fatigue resistance of steel fiber concrete are greatly improved compared with ordinary concrete. Since steel fiber concrete has high tensile strength, fracture toughness and fatigue resistance, it can be used in machine piers that bear dynamic loads, frame nodes of seismic structures and other parts.

6. Durability is significantly improved
Steel fiber concrete has good crack resistance, integrity and low shrinkage, so its waterproofness, impermeability, freeze-thaw resistance, heat resistance, wear resistance, cavitation resistance and corrosion resistance are significantly improved. It can be used for basement waterproofing and other projects.

Disadvantages of steel fiber concrete:

1. The technical characteristics of steel fiber concrete are that it can improve the toughness and tensile strength of concrete, but steel fibers are easy to agglomerate when mixed, and the concrete has poor workability, making it difficult to pump, difficult to construct and easy to rust.

2. The self-weight of steel fiber concrete is large, and a large amount of steel is used in manufacturing, which increases the consumption of steel and increases costs.

3. The main form of steel fiber failure during use is being pulled out, rather than being broken, which indicates that the adhesion of steel fiber to concrete is insufficient, which will affect the effect of improving the tensile strength of concrete. The principle of toughening and strengthening is that when cracks occur, the high modulus of steel and the high tensile strength of a single root prevent the further development of cracks; but due to the limited number, the effect of restraining micro cracks is not great, and the improvement of anti-seepage, freeze-thaw and other properties is not obvious.

4. The density of steel fiber is too high during construction, and it often sinks to the bottom of the concrete during vibrating and pouring, and it is impossible to distribute it evenly.

Extended information:
The fiber volume rate of ordinary steel fiber concrete is between 1% and 2%. Compared with ordinary concrete, the tensile strength is increased by 40% to 80%, the bending strength is increased by 60% to 120%, the shear strength is increased by 50% to 100%, and the compressive strength is increased by a small margin, generally between 0 and 25%, but the compressive toughness is greatly improved.

The surface of steel fiber concrete should be moistened for no less than 7 days. The longer the time, the better. Use wet straw bags or curing materials to cover the surface. Steel fiber conversion beams should be kept away from wind, sun, rain, etc. during maintenance. The construction beams should be sealed with wind and rain protection. For steel fiber conversion beams, the demoulding time should be strictly controlled after the concrete reaches the 28d strength specified in the specification. If construction is carried out in winter, antifreeze measures can be taken according to conventional methods.