A primerseal is a single stage sprayed seal treatment.
To create a primerseal, a primerbinder is sprayed onto a prepared but unprimed granular pavement surface. The primerbinder is then covered with a layer of size 7mm or 10mm aggregate, rolled and opened to controlled traffic. The primerbinder must be fluid enough to penetrate and adhere to the pavement surface as well as hold the aggregate. If not fluid enough, it can leave pinholes or “ball”; i.e. it may not form a continuous uniform and waterproof layer and/or may not bond to the underlying pavement surface. Cutback bitumen, usually containing about 15 to 20 parts cutter oil per 100 parts of bitumen (13 – 16%), and some adhesion agent, is the most common primerbinder used.
Primerseals are not designed to be a long lasting wearing surface and are typically covered by a final seal or an asphalt overlay 12 months to three years after they are laid down.
Primerseals can be used immediately after they are laid down.