Managing Your RAP

Publish date: 2024-05-05

Mill it Up

Cold milling is an integral part of the construction cycle of any road. Asphalt milling is used to remove an old and worn wearing course or the entire asphalt pavement. It can also be used to improve the surface friction or remove ruts on a wearing course that is otherwise in good condition.

Once those asphalt millings are off the roadway, they become a recycled material that can be put back into future roads. However, best practices for milling should always be considered in order to produce a consistent, quality product.

The speed of the milling machine can make or break both the quantity and the quality of the material milled. In order to achieve a quality milled material, start and stop slowly. Starting too fast will make a dip right off the gate. When starting, move forward at a slow pace so the rear tracks can walk into the cut which allows the hydraulics for all legs to adjust accordingly. When stopping, slow down before coming to a complete stop.

Also be sure to maintain a consistent speed when milling. Milling at high speeds puts unneeded wear on the machine and will create a coarse pattern. This also makes for larger RAP material, which means producers may have to run the material through a crusher before it’s used.

New machines have different drum speeds, which, of course, is different than machine speed. Running a machine in the highest drum speed at a lower machine speed will help achieve a fine texture quality, without the line spacing of a fine textured drum. This also makes for better sizing of RAP material.

Be sure to also mill surface and intermediate layers separately to help control quality.

Once asphalt millings are removed from the road surface, the contractor needs to find a place to store them until they can be reused.

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