Helix® is a short twisted steel 'micro bar' used as a structural replacement for conventional steel reinforcing. Helix® is much more than a fiber used for crack control. Due to its unique shape and resulting behaviour, Helix® can replace 50 to 100% of traditional steel reinforcing, while improving the shear strength and durability of concrete.
The image on the right shows the size of each Helix® micro rebar: just one inch long with a square cross section, the distance from one face to the other only .016" (.4mm). But there's a big difference between Helix® and other fibers: Helix® is TWISTED, with five full twists along the 1" length.
The secret of Helix® is the TWISTED square profile. Similar to a cork screw in a wine bottle stopper, the only way Helix® can be removed from the concrete is for it to be twisted out. The energy required to untwist Helix® matches very closely to the energy required to pull deformed rebar through concrete.
This sets Helix® apart from other fibers which rely solely on friction to resist pull-out. And it is this 'twisting' behaviour which allows Helix® to replace conventional steel reinforcement in a wide range of applications.
A 'medium' dosage of Helix® is about 15 pounds per cubic yard which means 170,000 micro bars dispersed throughout the concrete. That's a lot of 'untwisting' tensile strength which typically provides equivalent bending moment capacity, higher shear strength and better durability than conventional reinforcing.
For more technical information on Helix®, click here.
Helix® was invented in the 1990s at the Department of Engineering at the University of Michigan. One of the original researchers, Luke Pinkerton P Eng., went on to establish Polytorx, LLC which introduced Helix® into the market in 2003.
Since then over 13 million pounds of Helix® have been produced, the equivalent of 20,000 full height residential foundations.