Which joint type is made of three materials and can only accommodate movement of 1/4 inch?

A poured joint seal is designed specifically to be made of a combination of three materials, which typically include a sealant, a backing material, and a bonding agent. This construction makes it effective in providing a watertight seal while allowing for some limited movement of the bridge components. The ability to accommodate only 1/4 inch of movement is crucial for the integrity of bridge structures, as it helps maintain proper alignment and prevents excessive stress on the materials. This feature is particularly beneficial in environments with minimal expected movement, such as where the bridge's expansion and contraction due to temperature changes are controlled.

In contrast, other types of joints serve different purposes and have varying ranges of movement and material compositions. Understanding these differences is important for selecting the appropriate joint type based on the specific bridge design and expected movement characteristics.