The Current Method is Slow, Costly and Dirty.
Current 2-D asphalt paving machines, with their flat screeds, are only adequate when used on a flat surface. They have NO ability to adjust the amount of asphalt that is delivered across the width of the surface to be paved.
For example, when used to overlay an existing road surface that has typical road deformities such as depressions or ruts, and without any preparation work, they don't deliver enough material over the depressions. So when the heavy roller comes along the material around the depression compacts first, causing the roller with its flat compacting surface to bridge over the depression and the asphalt material doesn't fully compact. When this happens, either the material continues to compact over time and the original depression re-appears, or it starts to crack.
After cracks form, water seeps in, which further breaks down the asphalt.
And the dreaded pothole appears.
When this happens they must return to patch the potholes, which is only a temporary solution. When the road gets bad enough the entire surface must be rehabilitated.
The current method is to mill down the surface flat so current 2-D asphalt paving machines, with their flat screeds, can be effective.
The milled material is then hauled away, remixed and hauled back to repave the original surface. Unfortunately, this method re-processes 100% of the road surface to address a much smaller percentage of problem areas. Structurally, nothing is wrong with the majority of all asphalt that is reprocessed in this manner. This method is very time consuming and costly, as well as greatly contributing to the carbon output of the project. It also causes more and longer lane closures, which costs you time and money and causes even more carbon output.
In the U.S. alone, more than 70 Million Tons of asphalt is reprocessed this way every year. You see, they can't just mill out the damaged areas because they must provide a uniform flat surface for current 2-D asphalt paving machines to be effective. So they mill down every square inch of road surface and reprocess it in this way. The industry touts this as a recycling effort, however it is anything but a green process!
This inefficient cycle continually restarts all because current 2-D asphalt paving machines deliver asphalt with a single flat surface, which provides no ability to compensate for localized variations such as depressions, dips, bumps or ruts. They are a 2-Dimensional tool being used to address a 3-Dimensional problem.