What is the difference between tack coat and prime coat

This site uses Akismet to reduce spam. Learn how your comment data is processed. Toggle navigation. The application of bituminous material over an existing impervious pavement surface which has already been treated by a prime coat.

Seal coat is mainly applied on impervious surface of bituminous pavements as a top coat. A pre mixed sand bitumen hot mix seal coat is commonly used over the premixed carpet. However, asphalt prime materials and the gradation of aggregate bases have changed over the years and applications of prime are no longer necessary for most asphalt pavements.

In fact, their use can be detrimental to pavement performance. The following is a brief explanation of what prime coats are, what materials are typically used, and why its use has been discontinued by the Virginia Department Of Transportation and other specifiers. A prime coat is an application of a low viscosity asphalt to a granular base in preparation for an initial layer or surface course layer of asphalt.

There are four primary purposes for the application of a prime coat on an aggregate base course;. For a prime coat to be effective it must be able to penetrate into the base course. Tack coats are key in ensuring a long life for pavement by forming a strong bond between the old and new pavement. This bond prevents slippage and serves as protection from outside moisture and bacteria.

Without a tack coat, the layers in the road would separate, threatening the structural soundness of the road and leaving the surface vulnerable to water damage. Prime coats offer a temporary waterproofing top layer to further prevent water damage as well.

Tack and prime coats offer several additional perks including: asphalt cracking prevention, reduced dust during construction, and stronger material bonding, meaning future repairs are more manageable and less cumbersome.

Prior to the application of a tack coat, the surface should be completely clean, dry, and free from debris. The coat needs to be applied uniformly and in a thin layer to cover the entire surface.

Beware of too much tack coat ; this can cause slipping, while too little tack coat can cause debonding. Traffic should be kept off the pavement during this process, and tack should only be applied to existing HMA surfaces, the technical definition of asphalt.

Prime coats are a bit more complex than tack coats.