Chip sealing extends life of roadways

In an effort to maximize available resources and to extend the life of roadways, the Missouri Department of Transportation uses a pavement repair process called chip sealing to maintain some of the state’s lower volume roads. Chip seal operations are in full swing and MoDOT has prepared a series of videos titled “All About Chip Seals” to help drivers better understand this maintenance technique. These may be found on MoDOT Central District’s YouTube channel: Chip seals are about one third the cost of a conventional asphalt overlay averaging $15,000 per mile, as compared to an estimated $55,000 per mile for an asphalt overlay. Benefits of using chip seals include keeping water from penetrating paved surfaces causing damage and extending the life of the pavement for an additional five to seven years. Chip sealing also provides crack sealing and improved traction.After years of traffic and winter freeze-thaw cycles, small cracks develop in roadway pavement. If left untreated, moisture seeps into these cracks and forms potholes when the water freezes and expands. As the name implies, a chip-seal treatment seals cracks and helps prevent potholes from developing by applying a mix of materials to the road to extend the pavement life. The work includes spraying a heated film of asphalt liquid on the road, followed by placing fine rocks or chips on top. The chips are then compacted to make them adhere to the roadway. Finally, the excess loose chips are swept from the surface, leaving an improved roadway that will hold up longer than it would have without the treatment. A surface may be chip-sealed several times, as long as the road is structurally sound. The process gets its name from the “chips” or small crushed rock placed on the surface.  Chip seals differ from a pavement overlay as that type of road resurfacing involves laying down one layer of asphalt. The chip seal process is typically used on roads carrying lower traffic volumes which make up more than half of MoDOT’s roadway network. Motorists should lower their speeds on oiled and graveled surfaces. Delays are possible due to traffic buildup. Consider alternate routes, if available. Road and highway information is available 24/7 on the Traveler Information Map at or through MoDOT’s Smartphone app which you can download free for iPhone and Android phones.

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