What is the name of the joint constructed when there is an interruption of more than 30 minutes in the concreting operation?

The joint formed when there is an interruption in the concreting operation for over 30 minutes is referred to as a cold joint. This occurs because the concrete that is being poured sets and begins to harden, resulting in a layer of cured concrete at the interruption point. When additional concrete is poured onto this layer without proper preparation, it can lead to insufficient bonding between the old and new concrete, potentially impacting the structural integrity of the joint.

Cold joints are crucial considerations in construction because they can affect the performance and durability of concrete structures if not handled properly. By ensuring that concrete placements are continuous or by implementing appropriate measures at the cold joint, engineers can mitigate potential issues related to strength and water permeability at that interface.

In contrast, the other options refer to specific joint types with purposes distinct from those of a cold joint. Transverse construction joints are specifically designed to allow for the continuation of work across larger areas and often involve planned stops for pouring. Expansion and contraction joints serve to accommodate movements in structures due to thermal changes or other factors, rather than interruptions in the pouring process.