Asphalt cement is the basic ingredient of asphalt emulsions. In most cases, it makes up from 50 to 75 percent of the emulsion. Some properties of the asphalt significantly affect the finished emulsion. But there is not an exact correlation between the properties and the ability to emulsify the asphalt. The properties of the asphalt cement do affect the performance of the residual asphalt on the road.
Water is the second ingredient in an asphalt emulsion. Minerals or other materials in water can affect the production of stable emulsions. Water that is suitable for drinking may not be suitable for asphalt emulsions.
The chemical used as an emulsifier greatly influences the properties of an asphalt emulsion. The emulsifier keeps the asphalt particles in suspension and controls the breaking time. It also determines whether the emulsion is cationic or anionic (or non-ionic). Chemical compatibility of the emulsifying agent with the asphalt cement is essential for producing a stable emulsion.
The emulsion is produced by separately metering the soap and water solution and hot liquid asphalt into a colloid mill at predetermined rates and temperatures. The colloid mill shears the asphalt into microscopic particles. The size of the particles affects the physical properties of the emulsion.
Sometimes additional ingredients, including latex, polymers, acids and other additives are fed into the emulsion to further modify its physical characteristics.
