Seal coat consists of a layer of sprayed-on asphalt, followed by a thin layer of aggregate. The resulting surface is durable, flexible, weather-resistant and high in friction. A seal coat can extend the life of an existing pavement structure by sealing cracks and preventing moisture intrusion into the underlying layers.

Seal coat illustration

Illustration: Seal Coat

Seal coat photo

Photograph: Seal Coat

A: The asphalt is applied at a rate appropriate for the aggregate that will follow, the anticipated traffic and other factors. The viscosity of the asphalt is carefully selected to maintain proper consistency and adhesion over the expected range of temperatures.

B: The aggregate is spread over the fresh asphalt. A roller presses it into the asphalt to firmly bind it to the surface. Any remaining unbound aggregate is swept off the roadway. The aggregate size may vary based on cost, availability, desired ride quality and other factors.