In normal atmospheric conditions, Bitumen and water can't mix and will separate instantly. Emulsifiers are speciality chemicals used to stabilize the fine dispersion of bitumen droplets in water.
Depending on their chemical properties, emulsifiers are of two major types: Cationic and Anionic. Cationic emulsifiers provide a fine emulsion under strong acidic conditions, where normally concentrated hydrochloric acid is used for adjustment of final pH.
On the other hand Anionic emulsifiers provide a stable bitumen emulsion under strong alkaline condition, where normally Sodium Hydroxide is used for adjustment of final pH.
The emulsifiers can be base product which require neutralization/Acidification/Alkalisation at the time of emulsion production or can be a pre-neutralized and pH fixed (Ready), requiring no acid / alkali at the time of bitumen emulsion production.