Hot In Place Recycling Pre-Construction Material

·      RAP From Existing Roadway: HIR is different from conventional asphalt overlays or mill and fill procedures in that it uses the materials in the top layers of the existing asphalt pavement, not new aggregate produced to a tight specification band. Most times, this is sufficient but with remixing new aggregates or additional asphalt mix can be added to improve mix properties or provide additional materials for increased smoothness.

Rejuvenating Agents: Rejuvenating agents consist of rejuvenating oil, rejuvenating emulsion or soft asphalt binder. Soft asphalt binders are usually less expensive than rejuvenating oil or rejuvenating emulsion but they are not as efficient at rejuvenation. Polymers can be added to the soft binder and rejuvenating agents to help with specific properties. In order to achieve their intended purpose, rejuvenating agents must be:

• Easy to disperse
• Compatible with the aged asphalt binder
• Capable of altering the properties of the aged asphalt binder to the desired level
• Resistant to excessive hardening during hot mixing to ensure long-term durability
• Uniform/consistent from batch to batch
• Low in volatile organic compounds or contaminants to minimize smoking and volatile loss during construction

New HMA: In the Remixing process, up to 20-30% new HMA can be added to the HIR mixture to improve mixture properties or provide additional materials for increased smoothness. In the Repave process, a new HMA mix is placed and compacted at the same time as the recycled layer. With Surface Recycling, a surface course is placed as a separate operation.

New Aggregates: In the Remixing process, up to 20-30% new aggregate can be added to the HIR mixture to improve mixture properties or provide additional materials for increased smoothness.