Composition of bitumen and tar emulsion depends on the type of emulsifier used and the surface on globules will form. Direct emulsions are characterized by adsorption of emulsifier particles on the outer surface of the globules, and the reverse – on the inside.
Small emulsifier concentration leads to a disperse phase, but at the same time it also promotes destabilization of the emulsion over time. Increase in emulsifier concentration can achieve lower surface tension, which leads to the formation of an adsorption layer on the globules.
In addition, reduction in the emulsifier concentration leads to a reduction in the price of bitumen emulsion.
In order to achieve a strong bond between bitumen film and mineral material, its concentration in the emulsion should range from 55-70%. When working with stone materials the surface is pre-treated with hydrated lime, which promotes better adhesion of extracted bitumen from the emulsion.
Tar-bitumen emulsion is composed of bitumen and tar at 80:20 ratio and 2% kerosene. The ratio of binder to alkali solution is 70:30.
Bitumen composition also depends on the manufacturer. For example, bituminous emulsions manufactured by Kharkov plant consists of 48-52% of bitumen type BN-II and 52-48% aqueous emulsifier. Latter consisted from lie treated wood pine resin. This recipe provides a fast-disintegrating emulsion.
Groznenskiy oil plant proposed this emulsion composition 49% petroleum tar, 49% sodium hydroxide solution and 2% emulsifier. As the latter consisted of fat that formed soap.
Typical emulsion ingredients are bitumen or bitumen mixture with a solvent like diesel fuel.
New type of bitumen emulsion was developed to simplify the treatment of stone surfaces like reverse type: 60 % tar brand D-2, 40 % of bitumen brand BN-II, 2% kerosene. Tar-bitumen emulsion contains 70-75% of binder mix and 30-25% of aqueous sodium hydroxide.
Emulsion formation is significantly influenced by the brand and method of bitumen production. The ingredients used in the preparation process can affect the dispersion property of the emulsion from high to low. Some bitumen brands tend not to emulsify.