Orange County Branch Newsletter
December 2011
Sustainability
CIR Quick, Cost-Effective and Environmentally Friendly
By Sam Ali
Cold In-Place Recycling (CIR) uses a train of equipment that mills, screens, and crushes the existing asphalt pavement. Typically 3 to 5 inches of asphalt concrete pavement (AC) is milled. An asphalt rejuvenating material is then blended with the reclaimed material and the recycled mix is laid back down to form a new pavement structure.
Additional aggregate or other additives may be blended in the recycled mix to correct the gradation or improve the mix. The recycled mix may be placed with a paving machine or bladed into place. After placing the material, the recycled mix is then compacted. After a 3 to 5 day curing period, a new surface (typically hot-mix asphalt (HMA) or a seal coat) may be applied. The recycled asphalt may be emulsified, cutback or a soft asphalt cement; it may have rejuvenator oils, polymers or other additives; or it may be unmodified asphalt. The process moves quickly with minimal traffic delay. The old pavement milled at the beginning of the train is rejuvenated and then re-laid at the back of the train.
Benefits of Cold In-Place Recycling consist of the following:
- Aged, distressed pavements are replaced with recycled asphalt mix.
- In-place recycling reuses the existing aggregate and asphalt, reducing new raw material and hauling costs.
- Cracked pavement is removed, preventing future reflective cracking.
- Deformations such as potholes, ruts, bumps and shoved pavement are removed.
- Crowns can be re-established.
- Clearances under bridges and curb height can be restored.
- With the proper choice of materials, aged asphalt can be rejuvenated, and poor aggregate gradations can be corrected with added aggregate material.
- In-place recycling minimizes the time a lane is closed for re-construction.
- The recycled pavement can, itself, be recycled when its time has come.
The picture shows Cold In-Place Recycling project at the intersection of Weir Canyon Road and Santa Ana Canyon Road in Anaheim