What is emulsion bitumen
Emulsion bitumen is literally a mixture of two immiscible liquids, one of which is dispersed in the other and inseparable from each other.
Emulsion bitumen is a mixture of bitumen and water with an emulsifying substance. 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.
Since the provision of bitumen heating facilities and devices in remote areas is neither possible nor cost-effective, asphalt specialists tried to implement a kind of use of cold bitumen in road construction.
With the advent of bitumen emulsion, not only was it practically possible to use bitumen in the cold, but there was no defect in the use of mixed bitumen in this case.
History of making emulsion bitumen
This type was first patented by Hugh Allen Mackey in 1922. At a time when the automotive industry was booming and many roads were being built, this product caused a great revolution in the road construction industry.
Emulsion bitumen production in France, known as the birthplace of this technology, increased from 10,000 tons in 1923 to 300,000 tons during World War II and to 1.2 million tons in 1970.
Today, 30% of French roads are made of emulsion bitumen and are still under construction around the world. Most of the bitumens used in road construction are cool and are at normal temperature and in a paste state.
Therefore, in paved asphalt operations, they must first be liquefied with the help of heat and then a thin layer of them must be spread on the road surface.
Types of bitumen emulsifiers
Emulsifying agents include colloidal mineral emulsifiers such as bentonite soil “emulsion fire” and chemical emulsifiers such as soap.
Mineral emulsifiers such as “Emulsion Fire” bentonite are more resistant to chemical conditions than chemical emulsifiers.
In addition, the bentonite mineral emulsifier is more resistant to ultraviolet radiation than the chemical emulsifier.
Emulsion bitumen production method
To prepare emulsion bitumen, devices are known as fast rotating devices.
Water, molten bitumen and emulsifying agent in these devices are placed between the plates that rotate at high speed and the bitumen is dispersed due to dispersion in water due to the centrifugal force produced by the rotating plates.
The speed of the rotating plates is usually 3000 rpm, but this type can also be produced by low speed mixers, but in these cases a strong emulsifier must be used as well as bitumen that has a low melting point. Usually the amount of bitumen in the emulsion bitumen is about 50% and the amount of emulsifier used in this type varies from one hundred percent to five percent.
Reasons to use emulsion
Bitumen has applications such as adhesion between layers, sealing, protection against weather conditions and corrosion, and maintenance and repair of concrete, asphalt and metal surfaces.
For this purpose, the quality characteristics of bitumen should be improved and liquefied for use, which increased the benefits of bitumen by producing this type of bitumen. The advantages of bitumen emulsion are:
More reasonable price compared to soluble bitumen due to the use of water instead of oil, no need to heat during unloading, loading and distribution
Adhesion properties of rock material and its
Increased application speed due to the evaporation rate of water in bitumen compared to petroleum solvent
Climatic conditions during work (choice of bitumen type, equipment, working method and mixing plan depends on weather conditions during work)
Available tools and equipment
Reduce environmental pollution due to evaporation of oil in soluble bitumen or when heating it
Possibility to increase the quality of bitumen such as adhesion and viscosity according to the production process, which allows improving the properties of bitumen.
Ability to produce different types of emulsions with different percentages of bitumen for storage purposes such as cold ready mix and cold sealant
Type of stone material used
At present, the desired gluing is used in all hot and cold asphalt works, soil stabilization, types of protective asphalt and surface coating. Other applications are as follows:
Mixed asphalt in place
Sealing with stone material
Filling the cracks
One-layer surface asphalt
Hot asphalt mixtures
Protective and sealing asphalts
Cold asphalt mixtures
Multilayer surface asphalt
Penetration coating for permeable surfaces
Sealing with sand
Repairs and staining
Stone-free surface coating
Reasons for choosing and using emulsion bitumen
The scope of application of this bitumen is more than ordinary bitumen because in all places of application of soluble bitumen, this type can also be used. There are also other cases where only emulsion bitumen can be used, so cases There are certain cases where it is not possible to use soluble bitumen.
Of course, this does not mean that they can be used without checking and randomly, but their useful, effective and acceptable use requires the selection of emulsion bitumen appropriate to the working conditions.
In selecting, first of all, the type of execution operation used for this emulsion bitumen should be considered and after determining the type of execution operation, other project variables should also be considered.