What to do for construction joints in a 6" foundation mat? 1

[VYordan]

I am designing a build roughly 70'x 90'in plan with a 17.6'x 18' column grid with a perimeter concrete wall. It is basically a flexible mat foundation, so, control joints with cuts are not possible due to the continuos reinforcement needed in the slab.
There are thickened integral column footings which are 6'x6' and a thickened perimeter band below the wall. The slab is to be used as the floor surface. The structure is partially underground.

So, how do I deal with the construction joins and pour sequence to minimize cracks? Thanks.

 

[Den32]

If you will not have control joints, you should meet ACI recommendations for slabs without crack control joints (0.5% to 0.6% reinf. ratio).

As far as construction joint, as long as the reinforcement continues through (doesn't occur at a lap), probably nothing special is required. You could tell them to use a bonding adhesive to make sure the cured and new pours bond.......or have them roughen the surface is shear development is a concern. If it were a 'spanning' slab you would have them locate the Construction joint in specific locations, but since this is continually supported on soils, shouldn't be an issue (unless you want them to keep away from column footings, or other supported loads)

Other thoughts: is there a vapor barrier below? Or is a waterstop necessary at this Construction Joint?

 

[hokie66]

Relatively small pour, do it all in one go. And Den32 is correct about the amount of reinforcement you need.

 

[SrVaro]

I agree with hokie66. Or are you concerned with the the integral foundations that are being poured with the slab? Even with this the amount of overall concrete pour will be relatively small unless your foundation are deep.

 

[VYordan]

I am providing #3@8" T&B EW or #4 @10" T&B EW No water stops are required. (0.5 %) Construction joints will be at center of the column grids. Also vapor barrier will be provided. Thanks.