Durability of thin surfacing systems, Part 4 Final report after nine years monitoring

Thin surfacing systems, as the term is currently understood, were introduced into the UK in 1991. Many sites with thin surfacing systems have reached or are approaching the end of their assumed lives so that a review of the service that can be expected from such surfacings can now be made with some confidence. The information collected from a selection of sites with thin surfacing systems has been evaluated in order to establish this understanding of their serviceable life. In this TRL Report, the results from visual condition, SCRIMtex and recovered binder properties are given for sites monitored over the last three years of this nine-year review (begun in 2001) together with analysis of these data and the results from preceding years on a total of 137 sites. The findings, now extended by a further three years’ monitoring since the last published report, indicate that, if a thin surfacing system is in a good condition after its first year in service, it will be serviceable for at least five years and the typical life of a thin surfacing system is about ten years, depending on the type of thin surfacing system and the condition of the substrate. The estimated life of the most commonly used systems (10 mm and 14 mm thin asphalt concrete and thin stone mastic asphalt systems), however, are all over 12 years.