What type of joint prevents two concrete sections from bonding together?

An isolation joint is designed to prevent two concrete sections from bonding together. This type of joint is essential in situations where different concrete elements need to move independently due to forces like settlement, thermal expansion, or contraction. Essentially, it allows for vertical and horizontal movements without causing cracking or damage in the adjoining concrete sections.

In specific applications, such as where concrete may be poured adjacent to other materials or where different structural elements meet, using an isolation joint ensures that each section can move freely. This is critical for scenarios involving foundations, pavements, or structures where varying loads or environmental conditions are expected.

The other types of joints serve different purposes. An expansion joint accommodates the expansion and contraction of concrete due to thermal changes but does not entirely prevent bonding. A control joint is primarily used to create a weakened plane before cracking occurs, allowing for orderly cracking at designated lines, which can still involve some bonding. A casting joint, while less commonly referred to, generally relates to the practice of pouring concrete, and does not specifically address the need to prevent bonding between two concrete elements.