Orange County Branch Newsletter

December 2011


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

Related Groups/Committees