Control Joint Needed in Pile Cap?

[PAeng22]

Pile caps are usually thick and fairly heavily reinforced for shear and flexural loading. It seems like cracking is not an issue even for a large pile cap (say 40' x 70'). We normally limit the W/C ratio to .45. I am wondering if anyone specifies control joints and if so what is the criteria, spacing, etc. I would appreciate any comments on this subject.

 

[dik]

I wouldn't normally put a joint in that, but, how thick? You may be dealing with mass concrete. Temperature differential becomes a bigger issue. You may have difficulty getting enough ready-mix trucks lined up...

Dik

 

[PAeng22]

Pile cap is 2'-6 thick...not really mass concrete.

 

[hokie66]

No construction joint is needed or desirable in a placement of that size.

 

[TXStructural]

I cannot imagine a single pile cap that would be 40' x 70'. Maybe a mat foundation for a wind turbine, but those aren't truly pile caps. A pile cap, by nature has to unify the loads going into a group of piles/piers, and having a joint negates this function. Shrinkage racks are no issue, and should be reduced by concrete mix design. If there are corrosion concerns, they should be addressed, but this is seldom an issue that can't be managed by other means.