A liquid made by milling hot binder into microscopic droplets dispersed in water, held apart by an emulsifying agent. Most emulsions carry about 55 to 70 percent asphalt residue and are labeled by charge (anionic, or cationic as in the C of CRS-2) and by how fast they set: rapid (RS), medium (MS) or slow (SS). They are used for tack coats, chip seals, slurry and micro-surfacing, and cold patch because they go down without heating binder to mixing temperature.
Distributor's loaded with CSS-1h, give the emulsion twenty minutes to turn black before you run trucks on it.
Also heard as
- emulsion
- emulsified asphalt
Do not mix it up with
- Cutback asphalt: A cutback is thinned with a petroleum solvent that evaporates; an emulsion is thinned with water.
Related terms
Break
The point when an emulsion's water separates and the asphalt droplets fuse, turning the film from brown to black.
Tack coat
A thin spray of asphalt between layers that bonds the new lift to the surface underneath.
Cutback asphalt
Binder thinned with a petroleum solvent so it flows at low temperature, then hardens as the solvent evaporates.
Asphalt binder
The black, sticky petroleum cement that glues the aggregate together in an asphalt mix.