Bitumen emulsions consist of particles with max size of 1 micron. Mostly they are light to dark brown color. The specific cast is determined by bitumen dispersion degree.
This material doesn’t have aggressive odor. Bitumen concentration can be different, but bitumen emulsions containing 50-55% of bitumen are the most common.
One of the key features of bitumen emulsions is their high viscosity and long storage life without significant loss of service properties.
Thanks to its corrosion protective performance, bitumen emulsions make good waterproof materials. Bitumen film ensures reliable water protection and, moreover, it is sufficiently resistant to acids and alkali.
The main difference of bitumen emulsion from suspension is the smaller particle size. In suspensions, the size of the particles is larger than 10 micron. The difference, which allows us to determine if the product is, in fact, an emulsion, is the suspension state and precipitation of bitumen particles under external influence.
It is impossible to make emulsion of bitumen and water without adjusting interfacial tension. This can be achieved either by reduction of surface area of all particles or by reducing interfacial tension.
To maintain the required degree of dispersion and stability of bitumen emulsion, one needs to create such conditions, where energy is reduced due to the decrease of interfacial tension on the boundary between water and bitumen. This can be done by adding a surfactant, i.e. emulsifier into the emulsion. The surfactant attaches itself to the surface of bitumen particles and reduces the interfacial tensions. Due to the presence of the surfactant, bitumen particles in the emulsion do not come into direct contact with each other.
The emulsifier and the method of emulsion production is selected based on initial bitumen properties, in particular on its melting point.
Adsorption effects are well apparent even at small concentration of the emulsifier, sufficient for surface layer saturation. That is why emulsion stability limit is achieved already with low surfactant concentrations.
Various mineral and organic materials can be used as emulsifiers in production of bitumen emulsions: all types of soaps, fats, fatty acids, starch, sulfate cellulose, compound ethers, oleinic acids, etc.