The West Virginia Division of Highways (WVDOH) has a big toolbox when it comes to maintaining rural roads. In Mineral County, they’re using a surface treatment called fog sealing to prolong the life of Knobley Road and other roads in the county.
“This is one of the tools we use to extend the life of our roadways,” said Joe Pack, P.E., WVDOH Chief Engineer of District Operations. “It provides a new surface and sealant that will prevent water and salt from affecting the existing roadway.”
Fog sealing is just one of several types of surface sealing treatments highways departments can use to rejuvenate existing roads.
The process involves laying down a layer of stone, sand or other aggregate over a sticky sub coat. A final fog seal is then applied to seal the stone in place, a lot like sealing a driveway.
The sub coat and fog seal are basically liquid asphalt that often contains polymers to make a tough, long-wearing surface. A fresh fog seal can extend the life of the pavement by several years.
When a paved road starts to turn gray, it’s because the asphalt is starting to oxidize. Fog sealing can fill in the microscopic cracks in the oxidized asphalt and give the road extra life.
“It comes in at a fraction of the cost of paving,” Pack said. “We get a good bang for our buck with this treatment.”
But until the job is complete, fog seal on an asphalt road can look to an untrained eye like the road is being tarred and chipped.
Pack likened a tar and chip road to making a lasagna. Workers start with a gravel road, spray down a layer of sticky tack, and add another layer of stone. Then they lay another layer of tack and stone to make a relatively tough road surface.
Fog sealing can be done to either an existing tar and chip road to extend its life, or to a paved road. The sub coat and aggregate fill in any cracks or gaps in the pavement, and the final fog seal seals the entire roadway.
Once the final fog seal is down, the road can be restriped. District 5 Engineer Lee Thorne, P.E. said contractors hope to paint the new road stripes on Knobley Road within the next few weeks.
