California Department of Transportation
 

Cold In-Place Recycling (CIPR)

Cold In-Place Recycling (CIPR) is an on-grade method of pavement rehabilitation that consists of milling the existing asphalt concrete pavement to a depth between 2 to 4 inches; mixing the cold milled material with emulsified recycling agent and other additives as needed; spreading and compacting the recycled mixture; and overlaying the recycled surface with a new layer of hot mix asphalt (HMA). Foamed asphalt can be used as a recycling agent instead of asphalt emulsion, but fine aggregates may need to be added to the recycled mixture.


Smoothing Machine

Cold In Place Recycling Train

Application

CIPR is best suited for moderate to low volume roadways that are structurally sufficient. CIPR can treat pavement distresses and surface irregularities including:
  • Raveling
  • Weathering
  • Bleeding
  • Corrugations
  • Shoving
  • Slippage
  • Poor ride quality
  • Rutting
  • Patches
  • Shallow potholes
  • Cracking

 

Limitations

CIPR should not be used on pavements with:

  • High traffic volumes (no specific AADT limit, but CIPR surfaces tend to ravel under traffic)
  • Rubberized Hot Mix Asphalt(RHMA)
  • Deep cracking : must recycle at least 70% of the existing pavement thickness
  • Geosynthetic Pavement Interlayer (GPI)
  • Moisture related problems:
    • Poor drainage
    • Pumping
    • Saturated subgrade material
  • Numerous utility access points
  • Nighttime construction work (due to the asphaltic emulsion “breaking” process)
  • Cold or wet (if rain is forecast or imminent) weather:
    • Minimum pavement temperature = 60°F (16°C)
    • Minimum ambient temperature = 50°F (10°C) and rising
  • Surrounding urban areas (noise created by the recycling train may be problematic)

Implementation

Guidelines for CIPR use are currently under development and will available soon. In the interim, for approval to use the non-standard special provision (NSSP) for CIPR on a project, contact Hamid Moussavi of Materials Engineering and Testing Services (METS) at (916) 227-7234.

Interim Report - Construction Completion for Cold-In-Place Recycling (PDF, 3.3MB)

Please forward any questions/comments/suggestions toShira Rajendra(shira_rajendra@dot.ca.gov). Last updated 06/15/2011.