A Brief Savoir-faire of Steel Fibers

Steel fibers were introduced in the year 1960. From then onwards there have been many researches and instances that have proved to be advantageous and have overcome many limitations while adding the steel fibers to concrete. From the 1970’s the steel fibers started gathering momentum and have been used for commercial purposes.

A common application of steel fiber is that they are used in floor slab construction. Using these steel fibers in concrete not only saves money but also makes the floor slab joint free, crack free and without any curling. When these steel fibers are mixed into concrete in some of the applications, the steel fiber properties provide an alternative to the provision of conventional steel bars or welded fabric. The major applications of steel fiber reinforced concrete these days are pavements and industrial floors.

ASTM 820 is the standard specification for steel fiber reinforced concrete and this is the minimum requirement for steel fibers. The steel fibers that comply with ASTM 820 are divided into 5 types:

·         Type I – Cold drawn wire

·         Type II – Cut sheet

·         Type III – Melt extracted

·         Type IV –Mill cut

·         Type V – modified cold drawn wire

The tensile strength of the type I steel fiber i.e. Cold drawn wire are between 145,000 to 445,000 psi. While the Cut sheet, Melt extracted, Mill cut and Modified cold drawn wire have tensile strength of 50,000 psi. These steel fibers come in different lengths ranging from ¼ inch to more than 2 inches.

Steel Fibers come in following shapes:

Type I – Round wires with deformed ends

Type II – Rectangular or square rod shaped with dimples

Type V – Triangular cross section and twisted or crescent cross section or corrugated

As per the research carried out by different personnel’s they say that long fibers are good in terms of performance but they are difficult to blend and mix well in the concrete. And so the long fibers are high in terms of aspect ratio. If you want to measure the effectiveness of the fiber then the term aspect ratio is used. The formula of aspect ratio is Length/diameter. If the aspect ratio of a steel fiber is high, then the performance of the fiber is better.

These days it becomes difficult for industries to perform the maintenance and repair work of floors and pavements frequently. So, to eliminate this process the industries request for higher dosages of steel fibers which in turn increases the joint spacing. As these joint spacing increases there is a little scope for cracks thereby reducing the need for maintenance.