Air blowing is an important method used in the asphalt industry to change the properties of bitumen. In this process, air is passed through hot bitumen for a certain time. This method makes the bitumen harder, stronger, and more resistant to heat.
First, the bitumen is heated to a high temperature. After that, air is injected into the hot material from the bottom of the tank. When the air moves through the bitumen, a chemical reaction happens. Oxygen in the air reacts with the bitumen and changes its structure.
This reaction makes the bitumen thicker and less soft. At the same time, the softening point of the bitumen becomes higher. This means the bitumen can resist high temperatures better and does not become too soft in hot weather.
Air blowing also reduces the penetration of bitumen. Penetration is a measure of how soft the bitumen is. After the air blowing process, the penetration number becomes lower, which means the bitumen becomes harder and more stable.
Another important result of this process is better durability. Air-blown bitumen can resist weather changes more effectively. It is especially useful in places where the temperature is very high or where the asphalt needs to carry heavy traffic.
This method is often used to produce special types of bitumen for roofing, insulation, and industrial uses. It is also used when engineers need bitumen with specific properties that cannot be achieved with normal refining.
In conclusion, air blowing is a simple but very effective method to improve the quality of bitumen. By passing air through hot bitumen, its structure changes and its performance becomes better. This helps engineers produce stronger and more durable asphalt materials.