Bitumen emulsions are bitumen dispersed in water in small pieces. The width of the particles is usually between 1 and 5 microns. Bitumen emulsions are widely used in roadworks, construction and their repairs in many places.
Distilled petroleum products (kerosene, diesel oil, naphtha, etc.) are not used in the use of emulsions. In addition, energy use is less due to the lower heat requirement in the manufacturing process compared to hot mixes. It also significantly reduces environmental pollution by not using distilled petroleum products.
A desirable emulsion is slippery and brown in color. In the bitumen emulsion, the bitumen disperses in the water and forms an emulsion with the properties of water.
Bitumen forms the P-70 part of the emulsion. Emulsions are generally produced with bitumen with a penetration value of 100 to 250. However, bitumen hardness may change due to climatic conditions.
Bitumen emulsion properties vary according to the chemicals used as emulsifiers. These substances determine whether the emulsion is anionic, cationic or nonionic. In addition, emulsifiers keep the bitumen particles stable and ensure that the bitumen adheres to the aggregate surface at the appropriate time and form.
Water increases the consistency of bitumen emulsion. The water to be used must be suitable for the emulsion to be produced.
What are the Bitumen Emulsion Types?
With the evaporation of the water in the area where it is applied, it creates a black layer that is waterproof and increases the adhesion strength. In anionic emulsions, the particles are spherical and small. These emulsions are safe against fire and pollute the environment less. However, they cannot be used with all kinds of aggregates and are sensitive to precipitation.
It is used as a bituminous binder, primer and adhesive material in road pavements. Cationic emulsions are less sensitive to precipitation. Also, more bitumen can be dispersed in the water without changing the quality of the emulsion.
What are the Usage Areas of Bitumen Emulsions?
Micro Coatings is a polymer-added cold mix superstructure material used to improve the deterioration of road and airport coatings.
Slurry seal
It consists of asphalt emulsion, fine aggregate, water and mineral filler. Slurry seal can fill small cracks in asphalt pavement. Therefore, small cracks in solid coatings can be successfully repaired.
Chip seal surface repair
It is a much more economical method. With the use of this method, the worn asphalt surfaces are renewed, the strength is increased and thus the superstructure is protected. First, the emulsion is applied by spraying it onto the application surface with an asphalt finisher. Afterwards, clean gravel is regularly laid. Third, the aggregate is compacted with a rubber tire. And finally, excess aggregates are swept away from the road.
Fog seal
It is the application of an aqueous emulsion. This method is applied to reduce aggregate loss in aged asphalt structure. This method is also used to fill small cracks on the asphalt surface.
Recycling
It is the reuse of asphalt pavement. Recycling of asphalt pavement has many advantages. These;
It is more economical.
The road structure can be improved.
It eliminates the waste problem.
In this way, existing resources are preserved.
Cold Mix Bitumen Emulsions
The use of bitumen emulsions and aggregates has been practiced in many countries for a long time. However, such mixtures were not considered as a pavement material to be used on roads with heavy traffic until the early 1980s. In these years, the reactions put forward to prevent the rapid depletion of energy resources and to reduce environmental pollution, especially in the USA. It has expanded the use of cold mix materials as a carrier layer in the road superstructure in some countries, including Turkey.
Bitumen and aggregate do not need to be heated in cold mixes. For this reason, there is no need for aggregate dryers and heating systems. Also, thinner petroleum fluids are not needed to increase the consistency of the asphalt emulsion.
These factors provide significant energy savings and make the use of such materials more economical.
Advantages of Bitumen Emulsions
It is more economical than hot mixtures.
There are no environmental pollution problems due to gas emissions during the production of hot mixtures.
Bitumen emulsion mixes are "cold mix". There is no need for the heating of the bitumen and the aggregate, hence the aggregate dryers and heating systems.
There is no need for thinner petroleum fluids. These factors save energy and make such materials more economical.
Since they are water-based, they do not pollute the environment. In the cold mixture, since the temperature is at room temperature, the harmful gases emitted by the hot mixtures are in liquid form. For this reason, significant gas diffusion does not occur.
Disadvantages of Bitumen Emulsions
Although bitumen emulsions have been used in pavement works for a long time, they are still not used as much as hot mixes due to their weak early age strength and slow development of strength. Due to some disadvantages, it is still not possible to use them in all situations.