Joint sealant
A flexible material installed in a joint to keep water, salt, and debris out while allowing the joint to open and close with temperature and shrinkage.
What does joint sealant mean?
Sealant choice depends on the joint's job: soft elastomeric sealants suit isolation and expansion joints that move, while semi-rigid epoxy or polyurea fillers are used in interior floor joints to support the joint edges against hard wheel traffic. Incompressible debris packed into an unsealed joint prevents it from closing and causes spalling at the edges. Sealants require a properly shaped reservoir and often a backer rod to perform.
In practice
Sealing driveway joints before winter keeps salt water out of the one place it most easily reaches the base.