As a St Louis asphalt contractor we wanted to talk about tack coat and its extreme importance in delivering a quality job. Tack coat is just as important as the asphalt itself for many reasons and is used in any projects that include asphalt maintenance or overlays. It is not necessary on new construction projects.
What is tack coat?
Tack coat is an asphalt emulsion that is applied between a new and existing asphalt surface to “bond” the two surfaces together. Its sole purpose is to bond the two layers together. It is applied on an existing asphalt surface just prior to a new asphalt surface overlay or patch. It is also applied on the edges of asphalt during a remove and replace patch.
Why Use Tack Coat?
Tack coat is simply a bonding agent. Without it asphalt layers or edges of a patch may separate which reduces the structural integrity of the asphalt road or asphalt parking lot. This separation may also allow water to penetrate the structure which is detrimental to asphalts deterioration.
How Should Tack Coat Be Applied?
There are two common ways for tack coat to be applied. It is important to make sure during your project tack coat is applied correctly and enough of the material is applied to ensure you receive a quality job. On roadway and large scale parking lot overlays a Distributor Truck should be used to apply tack coat evenly and thoroughly. On small patches in parking lots a standard pour pot or bucket with brush can be used applying the tack coat to the edges of the existing pavement.
As a leader in the asphalt paving St. Louis Market we have 3 computerized distributor trucks that are used every day on parking lot and roadway overlays. These distributors evenly apply tack coat across the existing asphalt ensuring a quality job.
What type of emulsion should be used for tack coats?
Normal practice in the US is to use a slow-setting emulsion that is diluted with water before application. Emulsion tack coat we commonly use is called SS-1H.
For more information on asphalt pavements see this link to the National Asphalt Pavement Association for some great questions & answer they have provided.