Extend Pavement Life With Thin Asphalt Overlays

Road owners are constantly investigating methods of ensuring that their existing roads have the longest possible lives. One of the most effective ways to accomplish this is through the application of thin asphalt overlays. In fact, according to a 1999 AASHTO survey, thin asphalt overlays were the most popular preventative maintenance treatments for asphalt and composite pavements.

Well-constructed pavements benefit from thin overlays, providing functional improvements to increase safety and smoothness. Additionally, thin asphalt overlays offer several other advantages that HMA industry professionals should be educated about when evaluating paving options:

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  • Long service life in conjunction with low life cycle costs
  • The ability to maintain grade and slope with minimal drainage impact, particularly with small nominal maximum aggregate size mixtures
  • Capable of withstanding heavy traffic and high shear stresses
  • No loose stones after initial construction
  • Very little or no dust generation during construction
  • No curing time required
  • Low tire-pavement noise generation
  • No binder runoff
  • The ability to recycle

While thin asphalt overlays have many benefits, it’s important to understand that they are not appropriate for all existing pavement surfaces. Careful examination of the existing pavement is important, in order to determine the structural, functional and drainage conditions of the pavement. In general, distresses that originate at the pavement surface are suitable for correction using thin overlays. For example, the following deficiencies are often good candidates for thin overlays:

  • Raveling
  • Longitudinal cracking that is not in the wheelpath
  • Transverse cracking

For a more detailed guide to understanding what needs to be done to various pavement surfaces prior to constructing a thin overlay, the following table can be used:

(Source: NAPA publication, Thin Overlays for Pavement Preservation)(Source: NAPA publication, Thin Overlays for Pavement Preservation)

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