Priming consists of introducing a bituminous binder into a previously compacted but untreated road surface. The binder is allowed to penetrate into the pavement surface to stabilize fines and turn the upper part into a hydrophobic layer several millimeters thick.
The purpose of prime coat is to:
- Stabilize the surface elements of an compacted (sub)base layer
- Reinforce the surface cohesion of the compacted (sub)base layer
- Waterproof the surface
The role of the prime coat is to:
- Protect the road base against site construction traffic and bad weather until it is further covered by subsequent layers(binder- or wearing course)
- Prepare a good bond for subsequent road layer
The bitumen emulsion used is slow-breaking with a binder content of approximately 60% or less, giving a low emulsion viscosity, allowing good distribution across the whole layer to be treated. Depending on the quality of the surface, the consistency of the sprayed binder is adapted.