What is Helix®?
Helix® is a short twisted steel 'micro bar' used as a structural replacement for conventional steel reinforcing. Due to its unique shape and resulting behaviour, Helix® can replace up 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' 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.
Helix® and the ICF Monopour
Helix® is ideal with the ICF monopour as the ready mix company now supplies, delivers and installs the reinforcing at the same time as the concrete. As the micro rebar is added to the concrete at the ready mix plant, you are guaranteed to get the exact dosage as specified by your structural engineer.
Without the rebar, a typical Nudura® MP panel, including the footing form, MP side supports, sized 8' long by 10' high weighs just 82 pounds.
For more technical information on Helix®, go to the STEEL FIBERS WEST website.
Determining the Helix® Dosage
To determine the correct dosage:
- Send Vancouver ICF your concrete structural drawings, including rebar schedule;
- Helix® then determines the required Helix® dosage to provide equivalent structural performance to the rebar schedule;
- If you require an engineered and sealed equivalence letter, our engineers Wicke Herfst Maver Consulting Inc. will review the Helix® design and provide this letter;
Wicke Herfst Maver Consulting Inc.
Wicke Herfst Maver Consulting Inc. have been conducting due diligence on Helix® since late 2012, researching the many tests and corroborating with other engineers across North America. They are well qualified to answer any technical questions you may have. Call (604)484-2859 or visit www.whmengineers.com.