Control Joints for Monolithic Slab? 1

[rincon05]

Should control joints be used for monolithic slabs, as with other types of slab construction? If so, would the following general rule apply?:

"The joints should be ¼ of the depth of the slab and no more than 2-3 times (in feet) of the thickness of the concrete (in inches). So 4"concrete should have joints 8-12' apart." (source: concretenetwork.com)

Would appreciate some guidance on this.

Thanks.

 

[UcfSE]

Yep. 0.25*depth is general. The max spacing looks excellent too. I would have said 12 feet max if possible, never more than 15 feet which is what you said basically. I haven't heard that rule before; it looks like good advice.

 

[Ron]

rincon05...those parameters are correct as UcfSE noted. See the following FAQ in this forum for corroboration and a bit more info....

http://eng-tips.com/faqs.cfm?fid=162

 

[JAE]

What do you mean by the distinction between "monolithic" slabs and "other types" of slab construction?

Please elaborate a bit on what you mean by monolithic.

 

[DaveFlax]

I agree. 2 1/2 times thickness or 10' is the norm for Portland cement concrete. However, if you are looking for a way to increase the joint spacing, you should look into Type K cement, which doesn't shrink. With Type K concrete joint spacing can be 100' or more.