How It's Made: Milling & Paving

Milling and paving is the process of removing the worn top layer of asphalt with a cold planer, then placing new hot asphalt in its place. The milled surface is cleaned and any needed repairs are made, and then the new mix is spread, compacted, and finished. For work on existing pavement, see asphalt milling.

What is cold milling?

Cold milling uses a machine called a cold planer, which has a rotating drum fitted with cutting teeth. The drum grinds the asphalt to a set depth as the machine moves forward. It is called cold milling because the existing pavement is not heated first. The removed material, often called millings or reclaimed asphalt, is loaded into trucks and can be reused in new asphalt mixes or as base material, depending on the project.

Why mill instead of paving over the old surface?

Milling removes deteriorated material, restores the correct grade, and keeps curbs, drains, and door thresholds at the right height. Paving directly over an old surface can raise the pavement and create a lip at curbs and edges. In some cases paving over is a reasonable choice, so the estimate should explain which approach is recommended and why.

How is the milled surface prepared?

After milling, the surface is swept clean so loose material does not end up under the new asphalt. Any base failures found during milling are repaired, and deep damage is patched. The drainage is checked so the new surface will still slope toward the outlets. A tack coat, which is a thin layer of liquid asphalt, is then applied to the old surface. It helps the new asphalt bond to the old one.

How is new asphalt placed?

Hot mix is delivered by truck and placed by a paver that spreads it to a consistent depth. The paver keeps the mix moving evenly, and crews work the edges and tight spots by hand where the machine cannot reach. Rollers then compact the mix while it is warm. Compaction is what gives the surface its density and helps it resist water.

How is the new surface finished?

Rolling continues until the asphalt reaches the required density, and the joints between passes are tightly compacted. Joints and edges are finished so water cannot easily get underneath. Traffic is kept off the new surface until it has cooled enough to hold its shape. Weather matters at every stage, because asphalt that is placed too cold will not compact properly.

How does milling help Ohio pavement?

Ohio's freeze-thaw cycles open small cracks in asphalt, and water entering those cracks expands when it freezes. Milling removes the weakened top layer before it fails completely, and the new surface can be built to drain properly. Milling is one tool among several, and whether it fits a given pavement depends on its condition.

Frequently asked questions

Does milling remove the entire driveway or parking lot?

Usually not. Milling removes a set depth of the top layer and leaves the base in place. The depth depends on the condition of the pavement and the plan for the new surface.

What happens to the milled material?

It is often reused, either blended into new asphalt or used as base material. How it is handled depends on the project and should be described in the estimate.

Is milling the same as resurfacing?

No. Resurfacing generally means placing a new layer over existing pavement. Milling is usually the removal step that comes before paving, and both can be part of the same job.

Bruck Construction offers a 1-year guarantee on all asphalt work and provides free estimates. Request a free estimate to find out whether milling fits your pavement.