Steel reinforcing fibers: Micro Rebar

Product developers characterize Helix 5-25 Micro-Rebar Concrete Reinforcement System as the only code approved material of its kind engineers can confidently specify as a replacement for primary structural reinforcing. Micro-Rebar are .5-mm diameter, 25-mm (1-in.) long fibers of twisted, high tensile (246 ksi), zinc-coated steel wire, dosed at 9 lb. to 70 lb. per cubic yard of concrete. Each pound of product has about 11,500 fibers.97 Helixi 400

In contrast to conventional steel rebar or reinforcing mesh, which function after concrete cracks, Helix has engineered Micro-Rebar to work prior to development of cracks, then hold them to tight dimensions. The product is designed to be an integral part of a properly prepared concrete mix; as a discontinuous system, it is embedded every cubic inch of the matrix, thereby capable of distributing a crack’s energy or load.

Compared to conventional rebar, Helix officials contend, this “micro” reinforcing approach allows the concrete achieve higher shear capacity and modulus of rupture (first crack strength), plus increased durability (life cycle) and ductility (flexibility). Micro-Rebar, they add, offers precast producers and concrete practitioners the ability to completely or partially eliminate conventional reinforcing steel and its attendant tying and placing labor. The patented design has been specified in 30-plus countries for cast-in-place or precast concrete slabs and structures whose combined surface area exceeds 50 million square feet. — Polytorx LLC/Helix Steel, Ann Arbor, Mich., 734/322-2114;