Which type of joint is specifically designed to accommodate expansion in concrete?

The expansion joint is specifically designed to accommodate the expansion and contraction of concrete due to temperature changes and moisture variations. Concrete naturally expands when heated and contracts when cooled; hence, expansion joints create a necessary gap between slabs or sections of concrete, allowing for this movement without causing cracks or structural issues.

These joints are typically filled with a compressible material that enables the concrete to expand into the joint space when necessary while preventing moisture infiltration and debris accumulation. They are strategically located throughout concrete flatwork, especially in larger slabs or areas where significant temperature fluctuations are expected, ensuring that the structural integrity is maintained over time.

Control joints primarily focus on controlling cracking by providing predetermined locations for cracks to occur, while construction joints are used to indicate where new concrete is placed against previously hardened concrete. Isolation joints, on the other hand, separate concrete sections from other structures, allowing for independent movement, but do not specifically address expansion as the primary function.