The recycling of asphalt road-making materials conserves natural resources and reduces the energy used in production. In countries where there is a shortage of road-building aggregate, or no indigenous bitumen, recycling is widely used in both construction and maintenance. The United Kingdom enjoys a plentiful supply of good quality aggregate and a comprehensive infrastructure to transport materials the relatively short distances between quarry, mixing plant and site but, nevertheless, the interest in recycling materials, which can be used in road building, has been growing rapidly in recent years. Conservation of resources has become an extremely important issue and the road construction industry is one of many that is being strongly encouraged by the government to take into account sustainable development. In this report, on a Highways Agency funded project, the performance of three full-scale road trials of recycled asphalt roadbase, produced in off-site mixing plants, is assessed. The test sections on the A20 were built in 1986 and contain up to 60 percent reclaimed material in the roadbase and basecourse. Those on the A500 and A23 were built in 1992 and 1993, respectively, and contain up to 30 percent reclaimed material. This report presents the data collected from annual monitoring of the sites including measurements of longitudinal profile, transient deflection, depth of rutting and observation of the visual condition of the road surface. Performance-related laboratory tests have also been carried out on the materials. Conclusions are drawn on the performance of the recycled asphalt up to 1997. (A)

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