Sprayed Seal

A sprayed seal is a thin layer of binder sprayed onto a pavement surface with a layer of aggregate incorporated and which is impervious to water. A Sprayed Seal is sometimes referred to as a "Spray Seal", a "Bitumen Seal" or a "Chip Seal".

Image: Queensland Department of Transport & Main Roads

The are a number of types of sprayed seals, including primerseals, two coat seals, final seals & reseals. A sprayed seal is constructed by pouring aggregate over a layer of liquid bitumen.


A hot mixture of bitumen and kerosene (binder) is sprayed on the road surface by a tanker to form a thin waterproof membrane. The bitumen is then covered with a thin layer of aggregate with tip trucks. The aggregate is then embedded into the bitumen by rolling with a multi wheeled roller to form a skid resistant surface. The sealing aggregate is typically of blue metal (basalt) gravel with a nominal diameter of 7mm, 10mm or 14mm. Crumb rubber or polymer can be added to the bitumen to provide greater flexibility and strength.

Useful Life

The life of a sprayed seal will depend on a number of environmental factors. Many Councils use an estimated useful life of somewhere between 8 and 25 years.

The table below shows the useful life adopted by a number of Councils. Please feel free to add your Councils information.

Council Adopted Life
Bundaberg Regional Council 15 years
Infrastructure Asset Useful Lives Report 13-30 years
Whittlesea City Council 12 Years

Related Pages

External Links & References

  1. Google Search (Sprayed Seal)
  2. Google Search (Chip Seal)
  3. Sprayed Sealing Practice in Australia
  4. Latrobe City Council Reseal Info Sheet
  5. Wikipedia
  6. USQ Picture Galllery
  7. RTA Sprayed Sealing Guide
  8. Oxidation of Bitumen Seals
  9. IPWEA Sprayed Seal Renewal Discussion
  10. Inspections of Sprayed Seal Trials (Austroads)
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