Traditional steel, i.e. wire mesh and rebar have been used for decades as a secondary reinforcement for concrete slabs. The purpose of the steel is to help hold broken pieces of concrete tightly together after the concrete has cracked. However, many times the steel is placed directly on the subgrade rendering the reinforcement useless. The Wire Reinforcement Institute states: “Only when the reinforcing steel is properly selected, placed and supported can its use be recommended or its cost warranted.”
Macro synthetic fibers were introduced in the year 2000 as an improved alternate to traditional steel as a secondary reinforcement for slabs-on-grade and composite metal-decks. Macro fibers are typically defined as fibers that are longer in length, up to 2 ¼”, and dosages ranging from 3.0 lbs. to 7.5 lbs. per cubic yard of concrete. The macro fibers are added directly into the concrete mix providing for a three dimensional reinforcement, whereas steel reinforcement must be placed before the placement of the concrete. The Wire Reinforcement Institute also states: “It is impossible to hook fabric uniformly to desired location after the concrete has been placed.”
Macro fibers have been used in numerous applications worldwide to replace traditional steel in projects ranging from parking lots, commercial and industrial floors to composite metal-decks.
Benefits to using macro synthetic fibers are: reduction of plastic and hardened concrete shrinkage cracking, improved impact resistance and residual strength. They are also non- corrosive unlike wire mesh and rebar. The fibers are also a considerable cost-savings vs. conventional labor-intensive steel reinforcement.