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The purpose of this research was to isolate and identify the reasons why some reseals have very long lives, and to identify which of these factors could economically be applied to reseals in future contracts, thus leading to a reduction in whole-of-life costs of chipsealing and pavement maintenance.

The life of a seal can be influenced by the seal design, quality of workmanship at time of construction, and material properties such as bitumen, aggregate and the pavement. 

This study of the New Zealand road asset maintenance management database has found a long-life seal is most likely to be:

• a single-coat seal
• a large chip size
• a 180/200 pen bitumen
• under less than 2,000 ADT
• on a good quality, strong, durable, well-drained pavement
• in a lower skid resistance demand category.

The aggregate mosaic is also usually flat and tightly packed, suggesting good quality of workmanship at the time of laying.

It was interesting to find long-life seals can be applied in any temperature extreme, in any rainfall category and in any degree of sunshine hours.

Keywords: chipseal, long-life seal, RAMM, road maintenance, seal life, seal performance, spray seal