Multiple emulsions were first applied in pharmaceutical, food and cosmetological industries. Road engineers also became interested in the new material.
Multiple emulsions can be produced in the process of preparation of inverted or highly concentrated emulsions, if the technology process is not correct or inital component measurements are off. This material is also obtained by application of “salty” bitumen, made of oil using desalting method, if the production process is incorrect.
For a long time, multiple emulsions were considered waste, but in time people came to understand that multiple emulsions can be the solution to many practical tasks.
A multiple emulsion is a substance where the dispersion phase is also an emulsion, containing droplets of another phase. Multiple emulsions are usually more viscous and flexible compared with traditional bitumen emulsions. They are very cost effective. Besides, they do not flow freely when applied.
So what is the main feature of multiple emulsions? First of all, they are both the material and its delivery system to the proper, often hard-to-reach, place.
If the multiple emulsion is selected properly. the same section can be treated with two emulsions at the same time: oil-in-water and water-in-oil. The material contains everything: active components, membrane systems and delivery systems. It is clear that to achieve the maximum effect from application of bitumen emulsion, it is necessary to solve the most difficult task i.e. to learn how to design the composition of the emulsion and develop technology of its mass production.
Scientists believe that development of such emulsions is important for two reasons. First of all, this emulsion doesn’t require additional water to be added. Addition of only the required amount of water increases bitumen concentration, so more viscous emulsions can be manufactured. Also it is possible to be more flexible with the quality of the initial raw materials to obtain a stable product.
In terms of road construction, multiple emulsions have other advantages as well: moisturizing effect, flexibility and adhesion to significantly sloped surfaces.
Five or six components are usually sufficient for preparation of a multiple bitumen emulsion, although in cosmetology 15 and more may be used. Nevertheless, the requirements for the production process are the same, whatever the emulsion is made fo:
- development and testing of emulsion spread on a surface;
- research of emulsion formation;
- learning how the emulsion and subgrade layers work together.
Application of multiple bitumen emulsions can eliminates the need to moisturize the treated surface, as they already have moistening effect.