Definition of emulsion can be either detailed and general, or short and concise, but it must contain two common positions:
- emulsions are dispersion systems;
- the imperative condition for existence of such systems is mutual indissolubility of components.
This research does not look into such bound dispersed systems as foamed bitumen (a G1/L2foam system). Bitumen emulsions used in road construction are dispersion systems of type L1/L2.
Emulsion is a coarse dispersion system consisting of two mutually indissoluble liquids, one of which (DP) is dispersed in the form of small droplets in the other (DM).
Road construction mostly uses bitumen emulsion of bitumen binder in a water medium.
Emulsions, just as any other coarse dispersion system, is not very stable, which can be helped by addition of special surfactants, also known as emulsifiers or stabilizers, or finely ground solid powders. IN this latter case, bitumen emulsion based on solid emulsifiers is called bitumen paste, regardless of the amount of powder emulsifier used.
Selection of surfactant and method of emulsion production also depend on bitumen structure. It should be considered also when choosing the type of modifying additive for production of modified bitumen based emulsions.