COLD MILLING

Pavement milling (cold planing, asphalt milling, or profiling) is the process of removing at least part of the surface of a paved area such as a road, bridge, or parking lot. Milling removes anywhere from just enough thickness to level and smooth the surface to a full depth removal. There are a number of different reasons for milling a paved area instead of simply repaving over the existing surface.

 

The Asphalt Recycling and Reclaiming Association has defined five classes of cold planing that the Federal Highway Administration has recognized. The classes are:

  • Class I - milling to remove surface irregularities

  • Class II - milling to uniform depth as shown on plans and specifications

  • Class III - same as class II with the addition of cross slope

  • Class IV - milling to the base or subgrade (full depth)

  • Class V - milling to different depths at different locations

MILL & OVERLAY

A “mill & overlay” is a street maintenance technique that requires the removal of the top layer (2") of a street by the grinding action of a large milling machine. After the top layer is removed, a new layer of bituminous pavement is put in its place.

The “milling” portion of the project typically takes one-to-two days. After the milling is completed, the “overlay” is placed in one-to-two days depending on the width of the roadway and traffic conditions. Before the new pavement is placed, the surface of the newly milled pavement is covered with a liquid asphalt tack coat to bond the old and new pavements.