What is a common use for expansion joints in concrete?

Expansion joints are essential in concrete construction as they play a critical role in accommodating the natural expansion and contraction of concrete due to temperature changes. When concrete is exposed to varying temperatures, it expands when heated and contracts when cooled. If these movements are not managed, stress can build up within the material, often leading to cracking, which can compromise the structural integrity and aesthetic quality of the concrete.

By integrating expansion joints into the design, contractors can effectively create a space that allows for this movement without causing damage. This is particularly important in large slabs of concrete, such as those used in roads, parking lots, or large floors, where the temperature fluctuations can induce significant expansion or contraction.

While other answers propose potential considerations related to concrete usage, they do not specifically address the primary function of expansion joints in managing thermal movements, which is crucial for maintaining the longevity and stability of concrete structures.