2 RAP characteristics

The characteristics of the RAP, such as the binder content, viscosity, aging, and gradation, affect the choice and dosage of the recycling agent. The recycling agent should be compatible with the RAP binder, and should restore its original properties or improve them. For example, if the RAP binder is too hard and brittle, a softer and more fluid recycling agent is needed to reduce the stiffness and increase the workability. If the RAP binder is too soft and sticky, a harder and more stable recycling agent is needed to increase the strength and resistance to rutting.

3 Performance requirements

The performance requirements of the recycled HMA depend on the traffic volume, climate, and design specifications of the project. The recycling agent should meet the performance criteria for the intended application, such as rutting resistance, fatigue resistance, moisture susceptibility, and low-temperature cracking. The recycling agent should also be compatible with the existing pavement structure, and should not cause any adverse effects on the underlying layers or the adjacent sections.

4 Environmental and economic factors

The environmental and economic factors also influence the selection of the recycling agent. The recycling agent should be environmentally friendly, and should not emit harmful emissions or leach contaminants into the soil or water. The recycling agent should also be cost-effective, and should not increase the overall cost of the project significantly. The availability, transportation, storage, and handling of the recycling agent should also be considered.

5 Testing and evaluation

The final step in selecting the best recycling agent for hot mix asphalt recycling is testing and evaluation. The recycling agent should be tested in the laboratory and in the field, using appropriate methods and standards, to verify its suitability and performance. The test results should be compared with the design specifications and the performance requirements, and any adjustments or modifications should be made accordingly. The evaluation should also include monitoring and feedback, to assess the long-term performance and durability of the recycled HMA.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?