Rotomilling-Cold Planing
Rotomilling
Also called planing, cold milling, or grinding, this process involves the controlled removal of asphalt or concrete to a specified depth with a carbide tooth-equipped cutting drum. The milled material - called grindings — can be left in place and used as base material or can be loaded into trucks to be used elsewhere on the project, returned to the asphalt plant for recycling, or used off the project on private gravel driveways or as fill material. The three types of rotomilling operations include:
Planing
During asphalt or concrete planning, only a portion of the surface is removed. Surface damage or irregularities (ruts, bumps, etc.) are removed, leaving a uniform, textured surface in preparation for an asphalt overlay. The existing roadway slope can be maintained, or it can be changed as required. Curb reveal milling involves tilting the Rotomill's cutting drum so that the asphalt overlay will maintain proper distances to curbs and gutters.
Micromilling
While asphalt planing and curb reveal milling are performed before an asphalt overlay, micromilling is performed either as a final surfacing operation following an overlay or as a bump-removal operation on roads that are not receiving an overlay. Micromilling produces a smooth, ready-for-traffic surface using a specialty cutting drum with many more teeth than a conventional drum.
Removal
Asphalt removal is the removal of the full depth of the existing asphalt. 1 1/2"-minus base material can also be removed. Asphalt removal by Rotomilling often saves money over other removal methods. Because Rotomilling produces a clean, sharp edge, eliminating the need for saw-cutting. Additionally, Rotomilling provides useable material - 95% passes a two-inch sieve, depending on the condition of the existing asphalt. Instead of paying for the disposal of asphalt slabs, the contractor can use the grindings as base material elsewhere on the project, return it to the plant for recycling, or sell it or give it away locally. We've found that anyone with a gravel road or parking lot will be willing to buy/take asphalt grindings.
Pulverization
Asphalt pulverization, like removal, involves cutting the full depth of the asphalt. Existing road surfaces can be pulverized and blended with the base materials on-site. The reuse and reclamation of the existing ACP are greener and carry less environmental impact than removing and disposing of existing bases.
Related terms included:
- Roadway obliteration
- In place grinding
CRABS - FDR - Road Recycling
Full Depth Reclamation, also known as FDR, or CRABS (Cement Recycled Base Stabilization), is a greener alternative to the standard "mill and fill" methods used. FDR also allows remedying the underlying base issues that may have initially caused the pavement problems.
By utilizing FDR, you are not only reusing existing ACP material, but you incorporate a stabilizing agent (cement, lime, or fly ash) to strengthen the base. You are effectively reducing the chances of future failure areas.
This process provides a fast construction cycle with minimal impact on local traffic.
PWY's portfolio of FDR and CRABs projects is extensive throughout Oregon, Montana, Washington, and Idaho.
Read more about the process and see detailed illustrations at cement.org
