Steel fiber reinforced concrete is an alternative to traditional reinforced concrete for certain application areas. Steel fibers are a discontinous, 3-dimensionally orientated, isotropic reinforcement, once they are mixed into the concrete. Steel fibers bridge the crack at very small crack openings, transfer stresses and develop post crack strength in the concrete.
A variety of fiber types (material, shape, size...) are available, their effect in concrete varies. Therefore steel fiber reinforced concrete shall never be simplified as a “concrete with steel fibers”. Steel fibers may be divided into five groups:
Type I - cold-drawn wire
Type II - cut sheet
Type III - melt-extracted
Type IV - shaved cold drawn wire
Type V - milled from blocks
The vast majority belongs to group I. the common and most performing anchorage type is the “hooked end”. For the same type of fiber, length/diameter and tensile strength have the biggest influence on fiber performance. The higher the l/d ratio, the better the performance of the steel fiber reinforced concrete.