The concern about energy resources depleting every year is rising. Mankind gradually starts to recall renewable energy, but it is still not capable to satisfy all business needs. Therefore there is a need not only to find “free” resources, but also save the existing ones.
Road construction sector is very energy intensive because each year thousands of roads are repaired in the world. The old “hot” technologies consume energy, so the solution is to use innovative building materials, such as bitumen emulsion. They do not require heating, which is a positive resolution to both saving energy, and good quality repair in road construction. So what is a bitumen emulsion? Let’s try to understand.
Bitumen emulsion – is a mixture of bitumen and water. Under normal conditions these substances do not mix. Therefore, special substances are introduced for connection of these components – emulsifiers, acids and alkalis. A mixture of water with such substances is called blending. In fact, bitumen emulsion – is asphalt for road construction that does not need preheating. Hence it saves energy resources.
Bitumen emulsions are divided into positive charge, negative charge and complex. Straight – organic micro droplets of 1-5 microns (bitumen, tars, oils, etc.) in water. Inverse – the opposite, water droplets in bitumen.
Also emulsions are divided by emulsifier type on cationic and anionic. Depending on its concentration, emulsion can be fast, medium, slow – setting. There are also ultra-stable, but they require the greatest amount of emulsifier.
Every year the world produces about 8 million tonnes of bitumen emulsion. 20% are anionic and 80% – cationic emulsion. The difference is in breaking depending on evaporation of water in anionic emulsions or chemical coagulation in cationic emulsions. Cationic emulsions are usually acid and anionic emulsions are alkaline. Since the majority of mineral materials used in road construction and repair, are composed of quartz, then cationic emulsions are used more often.
In special installations UVB-1 first, bitumen is heated, then added to water and emulsifier and optional acid stabilizer additives. It is stirred to obtain a blend. The next step – bitumen is supplied to mixer. UVB-1 installation is equipped with a colloid mill, provides a breakdown of bitumen into small particles, each of which interacts with emulsifier.
Emulsifier performs several important functions. Firstly, it changes the appearance of emulsion. Secondly, it provides stability during storage. Third, it slows the disintegration. And finally, fourthly, it improves adhesive properties of emulsion.
To obtain emulsions with new properties – several combinations can be used:
- change bitumen type;
- change concentration of bitumen;
- change emulsifier type;
- change concentration of emulsifier;
- change the ratio of components.