Steel fiber is a type of reinforcement material used in concrete and other construction materials to improve their strength, toughness, and crack resistance. It is made by cutting steel wire into short lengths, usually around 20-50 millimeters, with specific shapes and sizes to enhance the mechanical properties of the material.

Steel fibers are added to concrete, mortar, and other materials in small amounts, typically at a volume fraction of less than 1%. The fibers can be randomly dispersed or distributed in a specific pattern to achieve the desired properties. When the material is subjected to stress, the steel fibers act as crack inhibitors, helping to prevent the material from cracking and increasing its tensile strength.

Steel fibers can be used in a variety of applications, including reinforced concrete structures, shotcrete lining, flooring systems, and prefabricated concrete elements. They are also used in fireproofing and blast-resistant applications, as well as in tunneling and mining projects.

In general, steel fiber reinforced concrete has improved ductility, impact resistance, and fire resistance compared to conventional reinforced concrete. However, the use of steel fibers requires specialized knowledge and equipment for mixing, placement, and curing, and their use can increase the cost of the material.