Cold joints often form between two batches of concrete where the delivery and placement of the second batch is delayed. The initially placed and compacted concrete starts to set. And the two batches of concrete do not knit together properly. This problem becomes a potential area of weakness.
Not all the cold joints are due to delays between pours. Most appear because the foundation is complicated and built in stages. Because of this, the foundation is prevented from acting as an inertia dampening and vibration absorber.Â
Cold joints are not gaps in the concrete. They are usually linear. But there is a danger of small voids in areas where the concrete has not been fully compacted.
Generally, cold joints are not a problem structurally if the joint is under static conditions. But they perform badly when they experience vibrations generated by a machine.
