Is it worth adding fiber mesh to the concrete for the walls? Also is it worth increasing to 4,000 psi over 3,500 psi? Not sure if I'm getting more for my money upgrading. Any advise would be appreciated. Thanks.

I don't necessarilly see the benefit for fiber, especially in an ICF form. The fiber mostly helps with surface cracking. Since it enhances tension strength it really helps with shrinkage cracks. Since the only real testing of residential CC is for compressive strength, I do not think it will really effect your core results very much. If used, it is important that it dosn't effect the way the CC flows.

Along the lines of good CC flow you will probably want to use water reducer which improves CC flow without really effecting slump. One thing I picked up from my ICF guy is his mix. He substitutes 50% of the 7/8 agregate with Pea Gravel. This enhances flow and since it consolodates well ultimately compressve strength. As for strength, the engineering is based on minimum acceptable compressive strength, usualy 3000 PSI. We speced a 5 1/2 sack mix(3500PSI). All the core tests for the basement wall averaged around 6000 PSI. I just got the main wall core tests back and they averaged 5200PSI...

Ronmar thanks for the help. Greatly appreciated!

Ronmar thanks for the help. Greatly appreciated!

If you can get an engineer that understands it, use it. It controls micro fissures not just surface cracks. I always use Helix. Not screwing around with rebar is a dream. I have a foundation that is being built in a couple of weeks and it's footing, wall and floor pour in one step using Helix. I now do all my building in panels like sips and Helix makes that possible.

Agreed, Helix makes life much easier although we still use rebar for the door/window lintels.

Deleted duplicate post.

Yes, code requires it around openings but for the walls, footings and floors it's Helix. We only pour 3" floors because of Helix. Also I like 4" walls above grade with Helix saves money while giving you a superior product.

What is the cost of Helix? I cant find anything on line. Do you see savings in cost substituting Helix for rebar? Thanks!

I believe that http://www.fab-form.com/ is a Helix dealer. You can give them a call to get pricing. Your local concrete batch plant may be another source. Give them a call and see what they can do for you.

You might can find it here:


http://www.bing.com/search?q=helix+for+concrete+what+is+the+cost&qs=SC&pq=helix+for+cost&sk=SC1&sc=3-14&cvid=D61E74E7BDD74437ADACB43EFCB0C635&FORM=QBRE&sp=2

Get in touch with Helix, they have an expanding distributor base.

One question about Helix. Since it's steel, anyone noticed any problems with rust/corrosion?

Micro-Rebar is electroplated with zinc. Not as good as with hot dipped. Electroplated steel will last longer than un-coated but not as long as hot dipped.

Posted By Alton on 10 Apr 2017 01:35 AM
Micro-Rebar is electroplated with zinc. Not as good as with hot dipped. Electroplated steel will last longer than un-coated but not as long as hot dipped.

So, as long as it remains below the surface of the concrete, within the lifetime of the building, there shouldn't be any issues...

The lifespan of steel electroplated with zinc depends upon exposure conditions and the thickness of the coating. Normally, the coating is very thin because of cost. I think Helix Micro-Rebar will last a long time if the concrete is not exposed to salt spray or salt air like in coastal areas. It should definitely last longer than unprotected steel. I wonder if the company has done accelerated lifespan testing for Micro-Rebar inside of concrete.

I expect that Helix Micro-Rebar near the surface of concrete will corrode before uncoated steel that is protected by 1.5" or more of concrete. But without salt and a continuing moisture source, the difference may be be irrelevant.

Posted By jonr on 11 Apr 2017 05:55 PM
I expect that Helix Micro-Rebar near the surface of concrete will corrode before uncoated steel that is protected by 1.5" or more of concrete. But without salt and a continuing moisture source, the difference may be be irrelevant.

Right. Remember that we're talking about a wall structure here.  And one that should have a a few inches of insulation and a moisture barrier over it already.

For normal commercial/residential building construction, Helix is as durable as any steel rebar. There have been plenty of catastrophic steel rebar failures (e.g., parking garages) typically resulting resulting from salt induced corrosion. For harsh environmental condition construction (e.g., water work projects) where there is continuous moisture or salt exposure, basalt rebar is used and steel rebar or Helix should not be used.

What size rebar do you use (#4 or #5)? Also how many do you install (two pieces per window / door) and what is the placement in the ICF (2" from both sides of ICF)? Thanks for the help.