Forms when a late truck, a plug or a breakdown lets the last concrete placed stiffen before the next load arrives, so the two never knit together. The result is a weak plane, a leak path and often a visible line on finished walls. Retarders, keeping the leading edge alive and bulkheading a proper construction joint when a delay drags on are the standard defenses.
Third truck's 50 minutes out, so either we bulkhead it now or we're looking at a cold joint halfway up this wall.
When a delay cannot be avoided, a clean bulkhead and a planned construction joint beat a cold joint, even if it means sending a truck away.
Also heard as
- cold seam
Do not mix it up with
- Construction joint: A construction joint is a planned stop that is prepared and often doweled; a cold joint happens by accident.
Related terms
Construction joint
A planned stopping point between two placements, prepared so the next pour bonds to it or transfers load across it.
Retarder
An admixture that delays setting, used in hot weather, on long hauls and for big continuous placements.
Lift
One layer of concrete placed in a wall, column or mass pour, or the height cast between horizontal joints.
Pour
The act of placing concrete, or one placement itself, in everyday jobsite speech.