Mastic? Never heard of such a thing.

Mastic is a structural grade of “pourable pavement” used for sealing, filling and repairing many distresses in asphalt and concrete that cannot be corrected with hot crack filling or seal coating, but are too small for conventional patch-paving to be economical.  An alternative to other patching methods, mastic application does not involve saw cutting or cold milling; it melts into and becomes part of the existing pavement surface which means it will not peel or flake off, and no water can penetrate between the existing layer and the repair layer.

When properly applied, mastic forms a flexible, durable, traffic-resistant repair. Applications include filling large separations; correcting elevation issues; leveling uneven transitions; repairing spalled concrete or asphalt; filling small to medium sized potholes, and skin-patching alligatored areas (surface repair).  Longevity is typically 5+ years.