What is the purpose of jointing in concrete slabs?

The primary purpose of jointing in concrete slabs is to control cracking and allow for movement within the slab. Concrete is a rigid material that contracts and expands in response to temperature changes or moisture conditions. Without joints, these movements can lead to uncontrolled cracking, which can compromise the structural integrity and longevity of the slab.

Jointing creates predefined weaknesses in the concrete at intervals, effectively directing where the cracks should occur and allowing for controlled movement. This practice helps maintain the surface appearance and functionality of concrete slabs, particularly in large areas where stress distribution can lead to issues if not properly managed.

Other options discuss aspects unrelated to the fundamental function of jointing. For example, while jointing might indirectly influence surface appearance, it is not primarily for decorative purposes. Similarly, it does not significantly enhance thermal insulation properties or increase load-bearing capacity; those characteristics of concrete slabs are influenced by factors such as mix design and sub-base support rather than by the presence of expansion or contraction joints.