Form release agent pooling in keyway

[Gary Mac]

There is ongoing discussions regarding the ACI 318 and ACI 332 commentary discrepancy for permitting deformed bars to be contaminated with form release agents. I am not convinced the commercial and residential should be considered separately for compliance, however I have a related concern that needs to be considered.

When agents are haphazardly applied in erected residential wall forms, the product naturally coats and pools on the footing and especially in the keyway. Does this not create a possible void between the footing and in the keyway that would detrimentally effect the performance of the connection of the wall to the footing?

 

[emmgjld]

Yes, if excessive quantities are present, it could be a detriment.
My father, back in the 1960's, considered a wall base keyway to be an excellent collector of construction debris and such.
He taught me to avoid them.

 

[Gary Mac]

In this State the ACI 332 is applicable for residential projects as it is referenced in the IRC. ACI 332 Section 7.3.4.2 states there shall be a keyway at the wall footing intersection.

I have observed the keyway creates a reservoir where the release liquid collects and that condition is not contemplated in the narrow ACI 332 commentary that otherwise attempts to dismiss any value of diminished slippage performance of contaminated deformed bars.

As a local regulator I am in the process of creating official policy opinion that will effectively prohibit the use of release agent post form erection.

 

[lexpatrie]

Discussions? Between who? The code committees or some unrelated outside groups?

For that matter, is ACI 332 even adopted in the IRC, for example? Ok, never mind, I can read, you said it's adopted in the IRC.

The keyway is a construction convenience, erection aid, and/or code requirement, I'm not convinced it is "doing" anything in the formal structural sense vis-a-vis bar development length, splice length, or shear strength (via bearing on the keyway horizontally). I am also not aware of any collapses associated with this. The keyway is more of an erection convenience and probably offers some strength benefits, but it's probably not considered in the engineering sense, i.e. it's redundancy or extra potential reserve strength.

Form release agent or oil may interfere with development of bond on the rebar (not aware of any specific testing on this issue), but the pool has to saturate down into the footing or climb up the rebar from capillary action, such an effect is likely to be fairly limited, 2" or so, given the average keyway is formed with a flat 2x that's 1.5" nominal?

I think the concern with oil and contamination is along the full length of the bar, or more particularly in the development length or splice zones. I haven't seen any ACI 350 product specifications (water and wastewater treatment plants) that specifically ban form release oil or have any "cleanout" provisions for the keyway. If that were a typical requirement in the project specifications, that would at least lend some support to the concern.

Is there going to be a mandatory independent inspection to ensure this potential (arbitrary?) ban is enforced?