What is Helix®?
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.
How does Helix® work?
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' behavior 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.
History
Helix® was invented in the 1990s by Professor Antoine Naaman at the Department of Engineering, University of Michigan . The original patent 6,060,163, seen to the right was awarded on the 9th May 2000. One of the original researchers, Luke Pinkerton went on to establish Polytorx, LLC which introduced Helix® into the market in 2003.
Since then over 21 million pounds of Helix® have been produced, the equivalent of 30,000 full height residential foundations.