Bitumen is composed of numerous types of hydrocarbons that are grouped into four components: saturates, aromatics, resins and asphaltenes. In order to maintain the original physico-chemical structure, each of these groups must be present in very specific ratios to ensure that the bitumen performs well on the road.

In this way, the rejuvenated bitumen provides those fractions that the aged bitumen has lost and regenerates it to such an extent that its original characteristics are restored. The composition of bitumen with rejuvenators is determined by factors such as the working formula of the mix to be reconstituted, which is influenced by the recycling rate, the physical characteristics, and the components to be added to the aged binder to give it suitable characteristics.

When designing this special bitumen for recycling, we have to take these factors into account:

• Restoring the optimum composition of the aged bitumen to maintain the durability of the mixture.
• Taking the aged bitumen to an adequacy consistency (penetration).
• Giving the mixture the adequate binder content.