One interesting part of the asphalt process that you might not be aware of happens before any asphalt is laid. It’s called asphalt milling.
What is asphalt milling?
Milling is the process of removing the top layer of asphalt to a specified and even depth without disturbing the underlying subbase. This allows new asphalt to be laid down without increasing the height of the road and saves you time if the subbase doesn't need to be fixed. Thanks to the milling process curbs, drainage and other existing structures remain undisturbed.
How is asphalt milling done?
Asphalt milling is done using a milling machine. The first production milling machines were called Galions because Galion Iron Works manufactured them. They now come in various sizes to handle small or big jobs. Some of the larger machines, depending on the depth of the cut, can cut close to 15,000 square yards (13,000 square meters) a day, at 75 feet per minute.
The three basic components of a milling machine are:
- Cutting drum
- Conveyance system
The cutting drum rotates cutting heads across the surface, chewing up the existing asphalt to the depth of the cutting heads. The vacuum sucks up the milled material and deposits it where the conveyance system can then move it to a dump truck. The dump truck and the milling machine move together so the material is collected as it is removed from the surface, saving a lot of the time and effort that would be needed to collected later. The milled asphalt is recycled and reused in future paving projects.
Once the milling machine has removed the asphalt to the desired width and depth, the surface is swept and cleaned. This removes dust and debris that might cause problems with the new asphalt bonding to the surface. Once clean, the bond between the old and new asphalt should be very good, particularly as the old asphalt has a rough surface from the milling that will bond to the new better.
Proper milling allows new layers of asphalt to be laid evenly and at the same depth as the old surface, ensuring other structures like curbs and drainage ditches are not negatively affected. It also allows for the easy collection of old asphalt to be recycled for new applications.
Contact Wolf Paving to learn more about asphalt paving or to have your parking lot, road or driveway paved.
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