Cold Planing & Micro Milling

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Primary Resource

The inspector plays a vital role on every construction project ensuring that the completed operations comply with the plans and specifications. Recognizing that many agencies were inexperienced in performing cold planing and the maintenance operations that utilize cold planing, and hesitant to add the treatment to their pavement management systems because of their lack of familiarity, the Asphalt Recycling & Reclaiming Association worked with FHWA to develop the Basic Asphalt Recycling Manual (BARM) and a series of best practice guidelines. 

Copies of the BARM can be obtained at Information on where to obtain the best practice guidelines and additional CP resources can be found in the Additional Resources section. As with any construction process, if the owner agency is concerned with any part of the process, the owner agency should have a conversation with the contractor. 

Inspection Guidelines

CP is most often used as a surface preparation or grade preparation for other maintenance/rehabilitation techniques such as Hot In-Place Recycling (HIR), Cold Recycling (CR), Full Depth Reclamation (FDR), or asphalt overlays. Detailed information when CP is used with HIR, CR and FDR can be found in their respective sections. The following inspection guidelines refer to CP alone or when used for preparation for an asphalt overlay. Inspectors can help achieve a satisfactory project by ensuring that the process is in accordance with the contract documents as follows: 

Surface Preparation: Walk or drive the entire pavement section to be milled or micro milled for the day to ensure the surface has been properly prepared and that all pre-construction repairs have been performed. 

Acceptable Weather: Check conditions for anticipated heavy rainfall and freezing weather to determine if construction can start/continue.

Traffic Control: Verify that the proper traffic control is in place to keep the traveling public safe and piloted around the work area.

Quality Equipment: 

  • Verify that cold planer is of the size and type specified. 
  • Verify that nozzles and spray bars are working properly and are not plugged.
  • Verify that cold planer has the required depth, grade and cross slope indicators. 
  • Verify that haul trucks have bed covers and are of the required number and size. 
  • Verify that power brooms are of the required number and size.

Quality Workmanship: 

  • Verify that the cold planer is removing the material to the required depth, grade or cross slope. 
  • Verify that the correct surface texture is obtained. 
  • Verify that any spilled RAP is properly removed from the milled and/or existing surface 
  • Verify that the width of milling overlaps the previous pass by the required minimum amount. 
  • Check that longitudinal and transverse joints are properly constructed. 
  • Verify that any paving fabric or crack sealer that exceeds the maximum size is removed from the RAP. 
  • Verify that the milled surface is cleaned in accordance with the project requirements and temporary traffic markings, if required, are in place before allowing traffic on the milled surface.

Additional Resources

  • ARRA CP101 Recommended Construction Guidelines For Standard Cold Planing (CP) – A best practice guide for standard cold planing operations.
  • ARRA CP102 Recommended Construction Guidelines for Micro Milling (MM) – A best practice guide for micro milling operations.