Asphalt Paving Longevity
by Frank Brewer (Excerpted, in part with permission, from http://mpw.nashville.gov/ims/Paving/ProjectTypes.aspx#5)
Asphalt Paving is not cheap. The longer the life we get from any paving application, the less expensive it becomes so let us look at a few of the various means to extend pavement life.
Asphalt resurfacing is a method that has a couple of alternatives. One is a direct overlay; another is a milling and resurfacing process.
- The direct overlay is effective but raises the height of the pavement which can cause drainage problems as well as access problems, as you continually bring the street level up by the thickness of the asphalt mat laid down. Maintaining bridge approach clearance is also a problem.
- The milling and resurfacing process allows for the removal of the existing surface, to a specific height. When the resurface mat is placed, it will meet the existing height of the previous roadway. The material milled, known as reclaimed asphalt pavement (RAP) may be recycled as base material or reground and mixed with new hot-mix asphalt (HMA). Deformities such as rutting and potholes are easily corrected in the process.
- Both operations will have to involve readjustment of utilities so these costs are the same regardless of the operation chosen.
Another countermeasure is Crack Sealing. As pavement weathers and settles surface cracks form. Cracks should be treated promptly because they create openings for moisture to penetrate the pavement layers. Moisture or water can cause severe damage when trapped in the crack. Neglecting pavement cracking usually leads to accelerated deterioration of the pavement, resulting in significant problems such as potholes or base failures, which cause the serviceability of the pavement to decline. By using a hot polymer sealant, you are able to fill the crack to prevent the water intrusion and the service life of the roadway is extended.
Rejuvenation is also available. Rejuvenation is a surface treatment that replaces the lighter or volatile oils in the asphalt mix. These oils essentially evaporate over time. This process can be used on road surfaces that are in good condition but have been in place for a period of several years. It is less expensive than most processes; however, it will not correct surface deformities. A thorough sweeping prepares the roadway, the Surface Treatment is applied, and that is followed with a Curing treatment. The application of the volatile oils will add years of service life to the roadway.
Once the pavement is renewed there will be re-stripping and other activities involved. There are also additional methods to extend the service life to your roadways. Although there are expenses with these processes, the extended life of the roadway justifies the expenditures.
For more information on these and the additional methods, please contact TTAP (865-974-5255, 800-252-7623, ttap@utk.edu)
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