Helps retain flexibility. Asphalt pavement is considered a flexible pavement because of the binder that holds the aggregate together. The oils in the asphalt help keep the pavement flexible, and as the oils dry out the pavement becomes more brittle and loses its flexibility. "Sealer locks in the oils in asphalt and helps retain the properties of the asphalt itself over a period of time," Bushell says.
Replaces eroded surface. As pavement ages, fines on the surface are worn away by rain, traffic, wind, and other factors. The Asphalt Sealcoat Manufacturers Association (ASMA) says application of asphalt emulsion sealer replaces these fine particles.
Eases pavement cleaning. ASMA says that application of a sealcoat results in a smoother surface, which makes it easier to keep the pavement clean by sweeping.
Extends pavement life. Generally, sealer prevents the pavement from breaking down. "Sealcoating increases the longevity of the asphalt when compared to not maintaining it," Bushell says. "Costs are more prohibitive in terms of asphalt maintenance vs. replacement. It protects more cost effectively in the long run."
Saves client money. As the "Economics of Sealcoating" chart shows, use of sealcoating and other pavement maintenance techniques helps extend the life of the existing pavement, making use of sealer a cost-effective approach to pavement maintenance.
"Sealcoat functions as a Saran Wrap over the pavement," Lowis says. "Property managers often have a misconception about that and it's important for contractors to make sure they understand what it does."
Correcting Sealcoating Misconceptions
One of the problems with sealcoating is that while it has been around for more than 50 years some of the available information is inaccurate. Here are some of the things sealcoating doesn't do to an asphalt pavement:
- Sealcoating doesn't rejuvenate pavement. Sealer is merely a protective coating applied to the surface of the pavement. It does not enhance or bring back to life any pavement characteristics.
- Sealer doesn't provide structural improvements. Unlike a patch or an infrared repair, sealcoating does not alter the soundness of the pavement structure in any way.
- Sealcoating is not a pavement repair. Sealcoating is a pavement maintenance approach. It is used on essentially sound pavements to enhance their appearance and slow deterioration.
- Sealcoating doesn't repairs cracks. Cracks in asphalt pavement need to be repaired properly with hot or cold crack repair material. Sealcoating can fill hairline cracks but is not designed for larger cracking.
- Sealcoating doesn't make pavement more pliable. Asphalt is considered a flexible pavement because of the nature of asphalt itself. As it ages it becomes more brittle and subject to cracking. Sealcoating helps the asphalt mat resist this aging process so it retains its flexibility longer.
- All sealers are not alike. There are two primary types of sealer: asphalt emulsion-based sealer and refined coal tar sealer. Both are acceptable products for asphalt pavement (much as latex and oil are acceptable types of paint). Beyond that, manufacturers produce their own specific product that includes a special mix of additives and fillers designed to achieve a desired end result. Some manufacturers also offer two or three lines of sealer themselves, a "good-better-best" option.
- More sealer on the pavement is not necessarily better. Sealer needs to be applied according to manufacturer's recommendations and often that means two (or three) thin coats applied by spray or squeegee. Rich Kish, SealMaster regional manager, says contractors should not try to accomplish in one thick coat what they can accomplish in two thin coats. "Thicker application rates take longer to cure, which may lead to failure," Kish says.