One of the most difficult things about selecting an asphalt contractor can be sorting through the cacophony of opinions presented from various contractors. How exactly does one compare apples to oranges?
An important thing to remember is that there is often no “right” answer. When we train our estimators, we teach them that finding the right solution often involves both science and art. The most important thing is that you’re getting good value and that you orient your thinking toward the greatest cost-benefit. Sometimes the “best” solution is not possible from a budget perspective and you need to do the best with what you have.
That said, the most important thing is to think in terms of preventative maintenance. With most things, and especially pavements, you will spend much less money in the long term if you’re acting to prevent damage, rather than reacting to it. A house is a useful analogy. If good weather proofing is done—like paint, caulk, and moisture seals—more expensive repairs to the wood will be much less likely. Here follows a summary of asphalt maintenance options to consider:
Asphalt Crack Filling
Crack filling is far and away the best thing for preventatively maintaining asphalt. It is cheap and effective. It is appropriate when there are only single, solitary cracks (not widespread adjacent cracks or “alligator” cracks). Hot-apply rubberized products are the best, and the process is meant to prevent water from seeping through and eroding the base layer that the asphalt sits on, which will contribute to more widespread damage. We suggest reassessing cracks every year, even after they have been filled, because pavement shifts and cracks can reopen.
Asphalt Seal Coating
Seal coating is a process of applying a coating to the entire surface of the asphalt. The oil—or binder—that holds the asphalt together slowly erodes over time from moisture and oxidation from the sun. Asphalt sealing is meant to replenish and restore that binder and protect the asphalt underneath. It’s important to know that this process is only useful for prevention. Seal coating a badly cracked parking lot will provide no structural benefit. It has the added benefit that it is visually pleasing. It will make your parking lot look brand new. Make sure to ask your contractor how many gallons they are applying and how they dilute their product. Because this material is water soluble, it is very susceptible to manipulation by an unscrupulous contractor.
Full-Depth Asphalt Repair
More commonly referred to as “asphalt patching,” a full-depth asphalt repair involves removing the asphalt all the way down to the sub-base material. This could be 2 inches up to 6 inches or more. This is the best way to repair asphalt, but can sometimes only be practical for smaller areas because of cost. The Asphalt Institute (Lexington, KY) asserts that all pavement defects start in the base or sub-base layer and slowly work their way to the surface. The greatest advantage of a full-depth repair is that the contractor can assess these layers under the asphalt and rehabilitate them through compaction or bringing in more material. Because all failures start low and work their way up,
repairs should always extend 12-18” beyond the area of visible surface damage. Many contractors overlook this important detail. Failure to extend the repairs beyond the area of visible surface damage could results in the patched area soon having new cracks forming around its perimeter.
Overlays are generally used for larger areas of pavement repair, because it can be expensive to remove tons (pun intended) of asphalt material full depth. There are many ways to perform overlays, but the three most common are addressed here: (1) straight overlay, (2) grind (or mill) and overlay, and (3) petromat overlay. A straight overlay is the least expensive (and least effective) option. It usually involves grinding the perimeter of the overlay area only, to be able to taper to the adjacent pavement, and paving a new lift. This option can be susceptible to so-called “reflection cracking,” where the overlay area will eventually start to see the same pattern of cracking as the layer underneath. A grind and overlay involves grinding some portion of the pavement that is less than full depth. For example, a 6” thick pavement could have the top 2” removed through grinding, then repaved. A petromat overlay can be combined with either of the other two methods described. This involves applying a geotextile fabric over the surface area before paving the new lift, and helps prevent moisture from moving between the layers, and thus, reduces the formation of new cracks.