The issue of polymer-bitumen binder production has been highly relevant for many years. First of all, the reason for such an interest is that unlike bitumen emulsion, a polymer-bitumen binder is a product that cannot sustain its performance characteristics for a long period of time. A polymer-bitumen binder has a tendency to break down and that is why it requires effective blending.
It helps to remember that a polymer bitumen binder, produced with the help of SBS polymers, is exposed to a slow destructive process if subjected to high ambient temperatures.
The material’s properties will deteriorate faster the higher the temperature is. The main difficulty when working with polymer bitumen binders therefore, is the lag time between the preparation and the application of the binder. This lag time should be reduced as much as possible.
In today’s modern production climate, a production process, based on the use of colloid mills is considered to be the most effective method of polymer bitumen binder production. It was developed from a prototype of a usual mixer that was mounted in a supply tank. First bitumen and then polymer were supplied to this tank. At the next stage, this mixture was blended until the polymer dissolved. In this case, the temperature of the bitumen and efficiency of the mixer had a significant effect on the time of production.
The key point of this process has come down to this. The polymer is dissolved in a maltene fraction of bitumen and then creates a cover with a non-dissolved nucleus of the particle under it. The main task of a colloid mill is to remove the swollen cover and outcrop of the nucleus to create conditions necessary for its dissolution in bitumen. The substance should be circulated through a disperser for the polymer to dissolve.
There are also technologies that do not provide multiple passes of a substance. In these cases, polymer gets into the mill together with a flow of bitumen that is in a solid state. Passing through a gap between the rotor and the stator, the polymer is grinded down to the desired size. Then, the resulted substance requires blending to complete the dissolution of the polymer particles.
As you can see, the production of asphalt concrete and polymer bitumen binders are two separate processes with a different cyclicity. It means that it is necessary to get the required amount of modified bitumen and only then to start pr