AASHTO PP 93-18 (2020)

This standard determines an application rate for emulsified asphalt or performance-graded (PG) asphalt binder for tack coats.

A tack coat is the application of an emulsified asphalt or performance-graded (PG) asphalt binder, to an existing pavement surface just prior to placement of a pavement overlay course. The tack coat is used to ensure a good bond between an existing asphalt or concrete pavement and a pavement overlay course, between multiple pavement lifts of a structural pavement, and at any vertical surfaces to which a new pavement layer will be placed adjacent, such as curbs, gutters, utilities, and construction joints.