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Slab on Grade control joints

Slab on Grade control joints

Slab on Grade control joints

(OP)
I have seen details for control joints in flat slabs that have greased dowels or diamond dowels. I have seen notes to cut every other strand of WWF, cut every other bar, or stop the re-bars 2" short of the joint.

I have also heard other engineers stating that that is not required and that you just saw cut 1/4 T of the slab and leave it.
 
What are other engineers doing?

RE: Slab on Grade control joints

For SOG construction, I usually have 1-1/2" concrete cover to reinforcing (or 2" for 8" SOG or thicker) and sawcut 1-1/2" (or 2"). Timing for sawcutting is critical and I insist on this right from the beginning; I've had contractors sawcutting at 2AM... I normally use dowels at cold joints only (greased one side) and have only used diamond plates a couple of times and I don't reacall doing a slab with a keyway... even airport runways and taxiways.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

RE: Slab on Grade control joints

Specific dowel details probably perform better to allow shrinkage (when installed properly).

Meshes or mats with 50% or 2/3 cut at the joint have the advantage of stability during the placement -- easier to keep them in place than a bunch of isolated mats.

----
just call me Lo.

RE: Slab on Grade control joints

I've provided for each second bar going through the joint only in walls... not in slabs, and I don't know why. I have used keyways with walls I just realised.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

RE: Slab on Grade control joints

I usually think of greased dowels or diamond plate dowels for construction joints, not control joints. I suppose it is possible for heavier loading like a bridge deck or something that you might detail additional dowels/etc at control joints but it isn't typical in my experience for most slab on grade typical uses.

RE: Slab on Grade control joints

Yup...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

RE: Slab on Grade control joints

I think you can live with just cutting the top of the slab. Really depends what the end use is.

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