tack coat[′tak ‚kōt]
A thin layer of bitumen, road tar, or emulsion laid on a road to enhance adhesion of the course above it.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
asphalt tack coat
A light coating of liquid asphalt on an existing asphalt surface or on a portland cement concrete surface; used to ensure a bond between the old surface and the overlaying course.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.