What is the function of an expansion joint in concrete construction?

The function of an expansion joint in concrete construction is crucial for managing the natural movements of the material due to temperature changes. As concrete expands when heated and contracts when cooled, these movements can lead to cracking or structural issues if there are no provisions for them. Expansion joints are specifically designed spaces or gaps that allow for this expansion and contraction, thereby safeguarding the integrity of the structure over time.

While other options mention various aspects of concrete construction, they do not relate to the primary purpose of expansion joints. For instance, holding steel reinforcement in place is more related to the concrete's structural integrity and does not address temperature changes. Enhancing aesthetic value and preventing water infiltration pertain to different construction elements and concerns, but they don't capture the essential role of managing thermal movements, which is the primary function of expansion joints.