Fog seals are a pavement preservation technique utilizing a light application of diluted asphalt emulsion that helps to seal pavement before signs of distress arrive. The process involves spraying the existing pavement with 0.10 to 0.15 gal/SY of diluted asphalt emulsion from a distributor. To help improve skid resistance, a fine cover aggregate can also be applied by the distributer in a one-step process in the same pass as the spray application.
In preparation for the application, the road surface should be swept clean of any debris. Following the placement of the treatment, traffic should remain off the surface until the emulsion has fully cured (up to 2-4 hours depending on road and weather conditions).
Benefits of Fog Seals
- Seals the existing pavement preventing air and water intrusion
- Delays pavement oxidation
- Stops raveling and aggregate loss
- Enriches dry pavement
- Extends asphalt pavement life, reducing required maintenance and saving budget dollars
- Secures loose aggregate and improves stone retention when applied over chip seal
- Provides a new black finish after curing, increasing snow melt during the winter months
Where and When to Use Fog Seals
Fog seal applications should generally be applied to pavements in good overall condition and prior to the appearance of pavement distress. The underlying structure of the road should be sound, the pavement surface should be free of rutting, and all cracking should be sealed. Fog seals can also be applied over roads that have been chip sealed as a means to quickly seal loose aggregate and to prevent future aggregate loss.
When utilized at the correct time, fog seals can be applied as a mainline treatment to various types of roads from low volume town roads to high volume city streets and secondary state roads. The treatment can also be used to preserve and seal the shoulders on higher volume roadways and interstates.
In addition to applications on roads and highways, fog seals are also an effective preservation treatment for airport runways and taxiways, as well as for large parking lots. Similar to roadway applications, existing pavements should be in fair to good condition and free from major pavement distresses.