The mixture of binder, aggregates, and filler is known as Asphalt. It is also known as bitumen. It is also defined as A mixture of sand, gravel, a bituminous pitch which is used for the roofing, flooring and for the roads is called Asphalt.
It is one of the oldest materials in engineering in the world. It is a sticky, highly viscous and black or semi-solid form of petroleum.
For its mixture, the aggregates are sand, gravel, and crushed rocks. The binder is used to bind aggregates to the cohesive mixture, the binder is used as the most common bitumen.
On roads, the asphalt gives the ability to distribute the load of traffic. There are normally the different layers in the pavement, the bottom layer is known as subgrade and the top layer of the road is called asphalt layer.
It is produced by the distillation of petroleum or from natural deposits. The use of asphalt or bitumen is very old. If it is heated it becomes soft. It is also used for the dam facing, waterproofing canals and sea works which reduces the weathering and mechanical damages.
Production Of Asphalt
Through the distillation process, at an oil refinery, crude petroleum is separated into various fractions. The asphalt is produced by these fractions. During the distillation process, it does not boil or evaporate.
1: Distilling The Crude:
The process is started by piping the crude petroleum from the storage tank to the heat exchanger where the temperature is raised rapidly for distillation. Then it is separated for refining into gasoline, diesel, kerosene and many other petroleum products. By the distillation process, the heavy deposit leftover.
2: Cutting Back:
Asphalt may be blended called cutting back with a volatile substance that produces a product. The volatile element evaporates leaving the solid asphalt when used for paving or for the construction. The evaporating speed of cutting agent determines the curing rate of it.
To create a product that is easy to mix with aggregates, asphalt may also be emulsified, which is pumped through the pipes. To reduce the capacity of it and to separate the water the emulsifying agent is added.
Sometimes the harder asphalt is crushed to form a powder. For the construction of pavement powdered, it is usually mixed with the oil and aggregates for the construction of pavement. Heat and pressure work is done to amalgamate powder, aggregate, and oil.
5: Air Blowing:
If it is used for the coating purpose, it may have air injected into it. During the air blowing process, asphalt is heated at 500 Fahrenheit. Than air bubbles forced into a liquid for several hours. it remaining in a liquid state when cooled in the result.
Quality Control During Manufacturing
Properties of petroleum affect the properties of asphalt due to the fact that different oil fields and refining methods can result in crude oils with very diverse characteristics. When it is used for construction purposes three factors must be considered;
It is based on the viscosity at a given temperature. Careless mixing and temperature control can cause more damage to pave asphalt during the hardening phase. When determining paving it consistency a standardized penetration test is specified.
The purity test is easy to test it. It is made completely of carbon disulfide soluble bitumen. Refined asphalt is 99.5% soluble in carbon disulfide.
After the production of it, it must be free of moisture. Above heating 212 Fahrenheit the moisture may cause asphalt to foam because the foam will release fumes that can flash.
Types Of Asphalt
There are 5 mainly types
1: Hot Asphalt:
This type which we usually see while driving. This type is easiest to work with when the temperature of its high. The permanent solution of the problem is hot asphalt but must be used immediately because when it completely cools it becomes like a hard rock.
2: Porous Asphalt:
To enable water to drain through the pavement this type of asphalt is used in parking lots. This pavement can last for more than twenty years.
3: Perpetual Pavement:
The combination of it and the multi-layer paving design process is called perpetual pavement. Perpetual pavements are long-lasting and durable.
4: Warm Mix Asphalt:
it is produced as same as hot asphalt but the temperature is 50-100 degrees lower. There are few benefits of reducing the temperature of it such as reducing the fuel consumption and production of greenhouses gases.
It is generally used in combination with other materials so there are following uses of asphalts
1: Electrical Uses:
In electrical industries on mixing with wood tar, pitch, rubber, and resin high-grade it is used. The battery container is the best example of this.
2: Roadway Construction:
Asphalt bitumen is characterized by useful properties like waterproofness, resistance to weather, binding capacity and ability to provide a flexible surface. They are used in highway construction in both as surface materials and road foundations.
3: Asphaltic Paints:
It is also used in the paints. These paints are used for the damp walls and over concrete structures.