What Is Asphalt Milling?

What Is Asphalt Milling?

In road construction, there's more than one way to fix a bad street. Weather and general wear can create uneven road textures that gradually worsen to the point of requiring a new surface. Asphalt milling is a cost-effective and efficient way to fix a road without destroying the existing base layer. 

Asphalt Milling Explained

Asphalt milling also goes by the name cold milling or cold planing. These terms all refer to a method used to tear up the surface of existing pavement. This process creates a smooth base for road construction professionals to repave and create a better driving surface. Milling equipment might remove a single layer or the whole asphalt surface, depending on the project.

When to Use Asphalt Milling

Asphalt milling works well for applications where you want to repair or replace the top layer of asphalt without destroying and rebuilding the entire structure. Asphalt milling also creates a valuable side product, as discarded asphalt — called millings — can be recycled to resurface the pavement. Asphalt milling works on various surfaces, including roads, sidewalks, parking lots and driveways. 

Here are a few issues asphalt milling can fix:

  • Cracking: Surface flaws like cracks sometimes allow water or debris to enter and damage asphalt. Asphalt milling can restore an affected surface.
  • Bleeding: When oil-based asphalt binders cause oily films to appear on a road's surface, cold planing can remove the parts prone to bleeding to create a better street.
  • Raveling: As an asphalt road begins to disintegrate, the aggregate materials left behind result in a rougher, more dangerous surface. Cold milling collects these materials so they can be used in a new application. 

How the Process Works

Here are the steps involved in asphalt milling:

  1. Assess: Consider the current asphalt and decide whether you could remove the top layer and create a better road surface. If so, cold planing is a good choice.
  2. Prepare: Once you determine the road's condition, you can use a milling machine to grind the top layer of asphalt. Machine operators adjust the depth of the material removed depending on the extent of the surface damage.
  3. Collect: Put the asphalt millings in a dump truck and save them for use in the new asphalt. This material works just like concrete or gravel aggregates. 
  4. Clean: Once you remove the road's top layer, sweep away any dust or loose milling. This step leaves a better surface for the new layer to stick to.
  5. Pave: Lay a new asphalt surface over the bottom layer of the road using the recycled aggregate material. 

Equipment Types Used in Asphalt Milling

Asphalt milling uses tools similar to those involved in other road construction processes. Here are the most common machines used in asphalt milling:

  • Milling machines: This equipment, known as a cold planer, uses a rotating drum and cutters to tear up the pavement's top surface. Once torn up, the material is milled into smaller pieces for reuse. 
  • Haul trucks: These dump trucks collect the milled road material from the milling machines to reuse later in the repaving process.
  • Water trucks: During the cleaning phase, water trucks allow workers to clear dust from the road, creating a clean surface for the new layer to stick.
  • Sweepers: These machines work well for clearing debris off the road after milling machines have torn up the surface. They work well for catching larger aggregate pieces a water truck can't wash away. 

After preparing the road surface for repaving, workers can use typical road paving equipment. Machines like asphalt pavers and compactors lay down new road layers and smooth them to create a surface that's ready to drive on again. 

Benefits of Asphalt Milling

In the road construction industry, you have several options for fixing roads, from patching potholes and cracks to ripping up and replacing the entire surface. Asphalt milling provides a middle ground, offering convenience while maintaining high-quality road surfaces. Here are a few reasons to choose this method:

  • Safety: By removing bumps, cracks or ruts, milling creates a safer paved surface for driving or walking.
  • Cost-effectiveness: Resurfacing the pavement can be significantly cheaper than replacing the entire asphalt surface and base materials.
  • Convenience: During the milling process, traffic can drive on the milled road while you pave the other lane. Milling also reduces total construction time. 
  • Eco-friendliness: Milling allows you to create a reusable aggregate material. Plus, it requires less processing, meaning lower energy and resource requirements. 

Get Rental Equipment for Asphalt Milling

Rent whatever you need from people who do whatever it takes. The Cat® Rental Store dealer network can provide a variety of road construction tools, including cold planers, sweepers and haul trucks for asphalt milling. Explore our equipment display online to learn more about our rental options. Once you find what you need, get a quick quote to discover your costs or find your nearest Cat dealer to get started.