Definition - What does Joint Filler mean?
Joint filler is a material that is used between two sections of concrete, which in contrast to concrete, is a relatively compressible material so that it will not fail as the concrete around it grows and shrinks due to temperature changes or movement. Joint filler prevents the premature failure of the concrete structure.
Corrosionpedia explains Joint Filler
Concrete is not compressible for the most part. Therefore, whenever a joint is required between two or more pieces of concrete, it is important that some space be allowed between them so that they do not fracture each other as they shrink or expand. Joint filler allows the walls of the concrete joint to compress against it, rather than the concrete slabs compressing against themselves.
Rubber, asphalt and other compressible materials are popular joint filler material choices.
Joint filler also prevents the introduction of other materials that are not compressible from entering the joint, which could cause concrete failure as well. The joint filler also helps prevent materials that may degrade the concrete from entering the joint.
Care should be taken to place a sealant on the joint filler so that water does not find its way into it, otherwise the water may freeze and render the compressible joint filler material unable to compress, thus potentially resulting in the concrete breaking.