Joints are critical to the performance of concrete parking structures because they allow movement caused by temperature change, drying shrinkage, and creep. Three types of joints are commonly used in concrete parking decks. Control joints, sometimes called contraction joints, are used on parking decks to reduce random cracking. Construction joints occur at the outer edge of each pour sequence. Isolation joints relieve stresses associated with volume change forces caused by shrinkage, thermal cycling, elastic shortening, and creep. They are also used to separate the floor slab from other structural elements of the building.
Whatever the joint type, proper filling and sealing ensures a smooth floor without bumps, rough spots, or voids. The ideal joint sealant material should be flexible and have enough bonding strength to adhere to joint surfaces. It should be hard enough that it doesn't deflect significantly under wheel loads and expose joint edges to damage. Although no single sealing material fully exhibits all these qualities, polyurethanes provide the most advantages. Polyurethane elastomeric sealants are normally best for withstanding traffic or surface abrasions. They are also well suited for sealing isolation joints not exposed to traffic.