Final answer:
The concrete key serves to enhance the bond and prevent sliding or movement between a concrete footing and the base of a concrete wall. It is a specific interlocking shape that provides mechanical connection and is typically shaped during the pouring phase using a wooden framework as a mold.
Step-by-step explanation:
The purpose of a concrete key between a concrete footing and the base of a concrete wall is to enhance the bond between these two structural elements. Essentially, this means increasing the resistance to sliding or movement within the joint. The key, also known as a keyed joint, is an enlarged section or a specific interlocking shape at the interface of the footing and the wall that helps prevent lateral movement and shear forces that might otherwise cause structural failure.
When constructing a wall, a wooden framework or mold is typically used to shape the poured concrete, forming the footing and the wall. Once the concrete sets, the wooden framework can be removed, leaving behind a solid, interconnected structure. The key is a crucial part of this process as it provides a mechanical connection that supplements the adhesion provided by the cured concrete alone.
It is worth noting that keys are often created during the initial pouring phase, meaning careful planning and execution are necessary to ensure their correct formation and placement. The implementation of a concrete key is a classic example of how engineering concepts are applied in construction to ensure the durability and integrity of a building.