...A Stitch in Time Saves Nine
A fog seal is a very inexpensive way to add a little asphalt and a lot of protection to pavement surfaces. A light application of a diluted asphalt emulsion is sprayed on the pavement surface to protect against traffic and the environment. A timely fog seal in about the 6th or 7th year of service (or other time interval, depending upon the state of the original surface and local conditions) can effectively stop raveling for an additional 1 to 4 years, when it will be time to reapply another fog seal or other surface treatment. Fog seals can also be used as a color coating to blacken a pavement, or differentiate pavement lanes. Fog seals are used on both low and high volume roads to:
- Renew and protect old oxidized asphalt surfaces
- Seal small cracks and surface voids
- Prevent damage to pavements placed in cold weather
- Prevent raveling of chip seals
- Prevent snow plow damage to chip seals
- Blacken new chip seals
- Prevent raveling of open-graded surfaces
- Maintain and delineate shoulders in high-volume roads
Fog seals are generally applied to pavements displaying low-to-moderate-severity weathering or raveling, and used only where the existing surface is sufficiently porous to absorb the emulsion.
Some agencies have had a lot success with fog sealing new chip seals. In some cases a lower shot rate is used for the initial emulsion application, and then a fog seal is sprayed over the chip seal up to a few weeks later. The fog seal serves two purposes: to tie down the chips, giving further protection, and to give a nice, black surface. The fog seal reduces the likelihood of shelling and also protects the seal against snow plow damage. The protected, black surface pleases the public, especially in residential areas.
There is a renewed interest in open-graded friction courses to improve safety by reducing back-spray and hydroplaning. Fog seals have been found to be an effective solution to the raveling problems traditionally associated with open-graded mixes.
Don’t Fog Seal If . . .
Fog seals are not effective for long-term crack sealing. And fog seals are not the answer when a pavement has low surrface texture, large cracks, rutting, shoving, or other structural deficiency. Your SemMaterials representative can help you determine better methods of solving those problems.
We Can Help
We formulate asphalt emulsions specifically for local conditions. Consult your local SemMaterials Representative for more information on the emulsion fog seal products available in your area, and for information on shot rates, preparation, use, handling, dilution, and getting the best value from the products used.