Bitumen emulsion is a mixture of fine Bitumen droplets and Emulsifiers dispersed in Water. Bitumen emulsifying agent is a substance that prevents bitumen particles from sticking to each other in water and causes bitumen to disperse completely in water. In this way, the emulsifying molecules surround the bitumen molecules and prevent the bitumen particles from accumulating and re-adhering to each other, and these particles are surrounded by water.
Bitumen emulsion is becoming popular in advanced countries due to its Advantages, ease of use, and better environmental compatibility, which is used in road construction and maintenance, as well as for waterproofing and sealing applications.
Types of Bitumen Emulsions
Bitumen emulsions are available in many different forms of cationic or anionic, with varying breaking or setting rates and binder types and contents.
Cationic Bitumen Emulsion
Emulsions in which the particles are positively charged are called cationic emulsions. When the emulsion is being produced the cations are adsorbed by bitumen droplets, negatively ions remain in the water.
Anionic Bitumen Emulsion
Emulsions in which the bitumen droplets are negatively charged are called anionic emulsions. Most often, fatty acid and resin acid alkaline salts are used. They are obtained by saponification of the liquid resin, called Tall-Oil. This substance is a residual, distilled substance, a by-product of the paper pulp industry from resinous wood treated using the “sulfate” process.
Advantages of Bitumen Emulsion
1- Bitumen types with high viscosity are heated before use to make them easier to use. This preparation process does not exist in emulsion bitumen, due to its low viscosity
2- The water in the bitumen emulsion causes to a decrease in viscosity. This enables bitumen emulsion to penetrate easily into cracks and small-scale pores.
3- Bitumen emulsion contain water; hence, its fire hazards are much less.
4- Bitumen emulsion is used in road construction instead of regular or refined bitumen. This type of asphalt is called cold asphalt.
5- Bitumen emulsion is used in many areas at a temperature range of 8 to 50 degrees Celsius.
6- Emulsion bitumen can be applied on wet surfaces, Unlike cutback bitumen.
7- No need for a ventilation system when using it in closed spaces. Because bitumen emulsion is made of water instead of petroleum solvents which may have a bad smell and toxicity.
8- Bitumen emulsion is cleaned easily with water just before it dries, while other types of bitumen require expensive special solvents.
Disadvantages of Bitumen Emulsion
1- Bitumen emulsion is easily washed by water and mustn’t be used on rainy days.
2- The separation of bitumen and water during storage and transportation is an important point of the bitumen emulsion.
3- It is required to protect bitumen emulsion from freezing during storage and transportation.
Type of Bituminous Emulsion Used for Road work
The type of bituminous emulsion used for road work depends on many factors including climate conditions, traffic volume and surface condition.
One of the most important factors in the different types of bitumen emulsion is the setting time. Longer setting times can cause significant disruption to traffic flow, as roads will be closed for longer. Conversely, bituminous emulsions with shorter setting times allow for minimal disruption following maintenance works.