Asphalt Grinding, Milling and Patching

Asphalt Grinding and Removal

Asphalt Grinding, Milling and Black Top Patching

Full depth asphalt mill patching is a high production process designed to achieve maximum efficiency in the removal and replacement of the entire cross section of asphalt pavement in the span of less than a day.  This process is ideal when there are time constraints. In certain circumstances where traffic flow requires continual access to properties, it is necessary to remove one traffic lane of failed pavement while the other traffic lane provides vehicle access to and from the site.

Full depth mill patching eliminates the need to jackhammer the pavement perimeter, excavate pavement by rudimentary means (backhoe or Excavator), and disturb the soil’s subgrade. A milling machine can quickly remove pavement to desired depth allowing Statewide to proof roll soil’s subgrade to ensure adequacy of compactibility of subgrade before replacement of repaired area with asphalt. It’s fast, less disruptive, minimizes jackhammer noise, and provides you with a cost savings.

The byproduct, asphalt rubble that was disposed of at landfills, is now processed on site by a milling machine into particle sizes that allow asphalt, millings to be reused in hot mix pavement or can be used on your job site in areas where the soils subgrade is unstable and needs to be undercut. Just remove poor subgrade material, place Typar soil stabilization fabric before installing the asphalt millings, and compact. You’ll have a compacted subgrade using the waste materials from your old asphalt and you’ll save money.

The Process:

• Identify areas of pavement failure and mark out with spray paint at corners.
• Use a tracked asphalt milling machine to remove the entire thickness of asphalt pavement down to soil’s subgrade.
• Conveyor milling materials into waiting dump trucks and haul off site.
• Proof roll with weighted dump truck to confirm minimal deflection/movement of subgrade.
• Undercut and stabilize deficient areas with asphalt millings available from site repairs.
• Trim edges of patched areas and apply tack coat to sides of patches.
• Install a specific thickness of bituminous base and surface course hot asphalt mix.
• Use sufficiently heavy compaction equipment to obtain desired density of pavement repair. Make sure asphalt roller cross rolls each patch to ensure proper compaction.
• Apply a bead of sealant around the edge of each patch to help minimize water penetration.

Partial Depth Mill Patching

Partial depth asphalt mill patching is a relatively new process that uses milling machine technology to save our customers a lot of money on repairs of certain types of deteriorated asphalt.  If a site visit determines that pavement deterioration is not linked to failure originating from the sub base, then mill patching is a viable option. In many instances, pavement deterioration occurs in only the top 1 inch or 2 inches of the asphalt.

The following list provides examples of surface deterioration that can be corrected using partial depth mill patching.

1. An old asphalt overlay was not put down properly and is peeling away in sections causing 1″ – 2″ potholes around the parking lot (overlay has delaminated from existing base pavement).
2. The top layer of asphalt is shoving in an area where traffic slows down abruptly (bus lane traffic).
3. Surface cracking (possibly due to drying out of the asphalt over a long period of time) has allowed water to penetrate into the pavement and cause deterioration from the top down.
4. Pavement has started to “ravel” from the top down. (Usually occurs due to poor compaction on asphalt overlay in cooler working conditions.)
5. The asphalt pavement is in a critical drainage area and drainage swales need to be cut into the pavement so the surface can be reshaped allowing water to drain properly.
6. Pavement shows signs of low and moderate severity alligator failures. Since pavement hasn’t fully failed to subgrade, use of milling machine to cut off surface course overlay into binder course pavement can reduce cost of repair by 50% without impacting performance of completed repair over time.

The Process:

• Lay out and mark each area to be mill patched. Make all patches square or rectangular and extend 2′ beyond visual edges of distress area.
• Grind the top 1″ – 3″ of asphalt with a milling machine and scrape it away leaving the bottom layers or “base course” of asphalt intact.
• Conveyor milled material is into waiting dump trucks and haul off site.
• Sweep the base pavement to a broom-clean condition.
• Apply a tack coat to the exposed asphalt base course and sides of each patch.
• Install bituminous surface course asphalt mix to the proper line and grade using an asphalt paver (material can be placed by hand for smaller patches).
• Compact the asphalt thoroughly using a steel drum vibratory roller.
• Apply a bead of sealant around the edge of each patch to help minimize water penetration.

What Causes Asphalt Pavement to Fail?

Assuming that the initial asphalt pavement was designed and constructed properly, the primary cause of failure is the penetration of water into the asphalt base. Oxidation of the pavement surface begins this process which caused the asphalt to dry and become brittle. This oxidation leads to the erosion of the top layer of fine particles and the appearance of larger stones and small cracks on the surface. If left untreated, these cracks grow over time and eventually allow water to penetrate to the base of the pavement. When water enters the base of the pavement, the base material moves and settles leading to further cracking and an “alligator appearance.” When the pavement reaches this stage the only option is removal and replacement of the old asphalt, which costs the most.

In short, your Asphalt Pavement will fail because of AIR & WATER, unless you are proactive to maintain the surface & extend the life of the asphalt. Like Death & Taxes, Air & Water are unavoidable to your asphalt pavement. Whatever the condition of your Asphalt Pavement is, if you want to keep your overall costs down, you will need to implement a plan to maintain your asphalt pavement before it has to be replaced!