Cold Joints in Concrete Wall 2

[akastud]

This may be a stupid question, but I can't seem to find information anywhere on the subject. Is it acceptable to have a horizontal control joint in a concrete wall? If so is there a preffered location for the joint? It seems to me like it is OK as you analyze the reinforcing steel in tension as if the concrete contributes nothing, and the concrete can still act in compression. It is the policy of our company to not allow these joints, but from a practicality standpoint it seems impossible to avoid them at times. I imagine that concrete forms can only hold so much in wet concrete if you can even get the forms as tall as some walls are. Any thoughts or insights?

Thanks, akastud

 

[DaveAtkins]

Yes, you can have a cold joint as you describe. The vertical reinforcing in the wall must be continuous through this cold joint.

DaveAtkins

 

[SlideRuleEra]

Horizontal construction joints (I assume this is the type control joint you are considering) are no problem with proper reinforcing; many sizable structures are constructed this way. For example, I was involved with a 600' tall concrete chimney shell that was jump formed (an 8' lift of concrete place every 24 to 48 hours). If my math is correct, that means there were 74 horizontal, full circumference construction joints in the structure. Walls are not different.

http://www.SlideRuleEra.net

 

[Zambo]

I would say a construction joint is a planned and properly detailed joint the location of which has been agreed with the designer.

A cold joint is more usually a mistake caused by an interuption of concrete supply.

With walls I think one of the main points is that the joint should be near the top (preferably at the top) of the formwork so that good levelling of the concrete and preparation of the joint are possible. If the joint is about 600mm or more from the top of the formwork then the concrete finisher will not be able to work well and a poor quality joint will be visible following removal of the formwork.