Asphalt milling, also known as cold planing, is the process of using a dedicated asphalt milling machine to grind down the an asphalt surface to a base that can then be repaved over. Milling machines can remove a small layer of asphalt to make the surface of the asphalt even and remove minor imperfections, or they can be set to go full depth milling – this depends on the condition of the asphalt and the desired results for the specific project.

Asphalt milling is a great and cost effective way to resurface asphalt. A full removal and reconstruction of an asphalt parking lot or roadway would be more cost intensive and would increase down time of the parking lot or roadway. Asphalt milling allows you to remove the top layer of asphalt and repave with new asphalt in a timely manner.

In this post we will go through some of the common reasons for asphalt milling, some of the equipment that is needed when asphalt milling, other than the milling machine itself, and why it is important to use an experienced operator for your asphalt milling projects.

 

Common reasons for asphalt milling

Asphalt milling is typically performed when there is damage to the asphalt that cannot be fixed by patching and / or crack sealing. Or when the problem areas are so large, it would make virtually no sense to try and repair just sections. So the best, most cost effective option is to remove a layer of the top portion of asphalt and repave over the existing base, with new asphalt.

Below is a list of some common damage that usually requires asphalt milling and repaving to remedy:

• Raveling: Raveling is when the aggregate within the asphalt starts to detach, creating a rough, gravel-like surface, instead of smooth asphalt.Asphalt milling can mill down this damaged layer to be re-paved with new asphalt.

 

• Shoving: Shoving is when the asphalt begins to have a wave-like surface. This is typically in high traffic areas that have a lot of stopping traffic. This is common at intersections where there is high traffic of vehicles braking. Larger commercial vehicles can increase this effect.Asphalt milling can level out areas that having asphalt shoving, helping create a smooth, even surface that can be re-paved over.

• Slippage Cracking & Pushing
  While slippage cracks and pushing can happen separately, at times they can happen together. Slippage cracks and pushing can occur in high traffic areas where braking and wheel turning is common. This type of damage can happen sooner and be accelerated when the surface asphalt mix is low strength and can also be caused by a poor bond between the top layer of asphalt and the base or asphalt below.

 

• Rutting: If you’ve ever driven on a busy road or roadway, you may notice that sometimes the asphalt begins to have long “ruts” in it, following the direction of the tire contact areas of traffic.

 

• Uneven Surfaces: Overtime, especially with heavy usage of the roadway or parking lot, the surface of the asphalt can begin to become uneven. The asphalt can begin to sag, swell up, and have impressions in the asphalt. Asphalt milling and then repaving can help solve this issue and bring the asphalt back to an even level.

 

• Damage from Vehicle Fluids: Fluid that leaks onto the asphalt from a vehicle or piece of equipment can damage the asphalt. Asphalt milling and repaving is a great way to renew the surface of your asphalt and remove any damage caused by vehicles to your parking lot or the roadway.

 

 

What Happens After Asphalt Milling?

After the asphalt milling process is complete, everything is cleaned up and the milled surface is prepared and ready to be repaved over. An asphalt contractor will then repave the roadway or parking lot with new asphalt, while keeping the existing asphalt base (saving money and time)

 

Benefits of Asphalt Milling

There are many benefits when it comes to asphalt milling to revive your parking lot of a roadway. Some of the benefits include, the cost, time, and there is also a benefit of less disturbance to the parking lot or roadway function of traffic.

Cost: The cost of milling an asphalt parking lot or roadway compared to a full demolition and repave can be substantially cheaper. When asphalt is milled, the base and foundation of the asphalt is maintained, making the final product require less work, resources, and materials.

Time: Asphalt milling can be quick in comparison to a full demolition and repaving project. An asphalt milling company can mill upwards of 50,000 square feet in a single day. Once milled, the surface can then be driven over before repaving.

Less Disturbance: When a parking lot or roadway is fully demolished to be repaved, this can create an extended period of time that affects the flow of traffic or parking lot usage. The section of a parking lot or roadway that has been milled can then be driven over, while another portion of the road or parking lot is being milled. The road or parking lot can then be used still, even before paving has begun and is completed.

Recycling: Asphalt millings can be recycled. The asphalt millings can be used in their milled form for roads or driveways or they can be sent back to the asphalt plant to be used in new asphalt, reducing waste material.

Specific Problematic Areas: If you own or manage a large roadway or parking lot, sometimes only a portion of the asphalt needs to be restored. With asphalt milling, it’s not necessary to mill the entire parking lot or roadway, sections of the lot or roadway can be milled and repaved. As long as the problematic area is large enough to warrant a partial milling project, it’s a great way to save some money if the rest of your parking lot is still in great condition.

 

Common Equipment Used When Milling

 

There are multiple pieces of construction equipment that is used when milling asphalt. There is the cold planer or what’s commonly referred to as the milling machine, then there are smaller milling attachments for skid steers (for tight corners and areas where the full size machine is too large to fit), there are dump trucks involved to collect and remove the millings, and there are sweepers and other tools to not only clean the area, but to prepare it to be paved after being milled.

Below we will further break down the details on the equipment that is commonly used on asphalt milling projects.

Cold Planer or Milling Machine (both names are common): When asphalt milling is being performed, the main piece of construction equipment that is utilized is the cold planer or whats commonly referred to as an asphalt milling machine. This is the machine that actually strips away the layer or layers of asphalt. It does so by using a large drum that has carbide teeth on it, and that drum grinds and rips down, to a specified depth, the layer or layers of asphalt. The ground down asphalt chunks (called asphalt millings) are then fed through a conveyor system that is built into the cold planer and using that conveyor system, the asphalt millings are then fed directly into the back of a dump truck or to a pile.

When an asphalt milling contractor is milling a parking lot or roadway, there are other pieces of equipment that are required to complete the job properly and efficiently. This equipment includes:

Dump Trucks: Dump trucks, more specifically tri-axle dump trucks are an essential part of any asphalt milling project. The milling machine grinds the asphalt down and then the asphalt millings are sent through a conveyor system out of the machine and through a chute. The dump truck needs to be positioned in front of the milling machine for the chute to send the millings into the bed of the truck. They can then be easily transported away from the project site. This method makes the process efficient where there are multiple dump trucks. As one dump truck is filled and goes to unload, another one takes it’s place, keeping the milling process going.

Sweeper Truck: A sweeper truck is not always a necessity, but definitely something you’d want on a milling project to keep the project clean and keep the milled surface clean and prepped for the new asphalt to be paved.
Whenever an asphalt milling project is underway, there are pieces of asphalt, asphalt millings, and other debris form the milling process that will make its way onto and around the project area.  A sweeper truck can be used to quickly and efficiently remove any debris from the project area as well as remove debris from the milled surface. This is not only important for just keeping the parking lot or roadway clean, it’s also necessary to remove any loose debris from the base, to help the new asphalt bond better to the existing base.

Broom Machine: A broom machine has a similar purpose to a sweeper truck, to keep the milled surface clean and ready for paving, as well as keep the general project area clean from debris as well. The key factor to the broom machine is it’s ability to fit and maneuver in smaller areas within the project where the sweeper truck is unable to fit. The broom machine is a great tool for milling projects as it increases efficiency, saves time, and ultimately can lead to a better overall finished project.

Skid Steer: Skid steers are another great tool to have on a milling project for multiple reasons. They can be used to remove large piles of millings that have been collected in an area by a broom machine or to collect millings that haven’t made it into the dump truck from the cold planer itself. While a sweeper truck can collect a lot of the debris that is not piled, sweeper trucks are not designed to collect and remove large piles of debris, this is where a skid steer becomes a key tool during an asphalt milling project.

Skid Steer With Milling Attachment: Skid steers with milling attachments are a great tool for areas where a full sized cold planer would never be able to fit. On many milling projects there are tight corners or very narrow areas where a full sized cold planer is unable to fit. With a skid steers size and maneuverability, a milling contractor is able to get into those tight or hard to reach places and mill areas that would otherwise be impossible to reach, providing a cleaner, uniformed and more precise milled area.

 

 

 

Why Perform Asphalt Milling for Repaving instead of a Complete Removal?

 

When comparing asphalt milling to a complete demolition and removal of the asphalt parking lot or roadway, asphalt milling is a lot more efficient, cheaper, and time effective. Almost all of the damage to asphalt happens at or near the surface and any issues that make their way below the surface, are typically caused by issues at or near the surface of the asphalt. Typically the bases of roadways, highways, or parking lots are still excellent for a new asphalt layer. After a specified depth of asphalt is removed, any other issues below can be address, then a fresh layer or fresh layers of asphalt, will be paved over and the result can last up to 25 years (depending on traffic, weather, and maintenance). 

Asphalt milling and repaving is a great way to revive an asphalt roadway or parking lot without having to completely demolish and repave. Asphalt milling can save you a lot of time and money, while reducing disturbance to drivers or to your customers. This guide may help you identify points on when it might be time to consult, but ultimately the best route to take to see if your asphalt is in need of a mill and repave is to contact a local asphalt contractor or milling contractor.