Bitumen Seal -> 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.
Construction
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.
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Related Pages
- Primerseal
- Prime and Seal
- Sealed Road
- Surface Treatment
- Wearing Surface
- Asphalt Overlay
- Sprayed Seal Useful Life Discussion
- Sprayed Seal Rejuvenation
External Links & References
- Google Search (Sprayed Seal)
- Google Search (Chip Seal)
- Sprayed Sealing Practice in Australia
- Latrobe City Council Reseal Info Sheet
- Wikipedia
- USQ Picture Galllery
- RTA Sprayed Sealing Guide
- Oxidation of Bitumen Seals
- IPWEA Sprayed Seal Renewal Discussion
- Inspections of Sprayed Seal Trials (Austroads)