Recycling of asphalt pavements

Hot in-place asphalt recycling has gained wider usage in Queensland since its introduction in March 1990. An area of approximately 2,000,000m2 has been recycled so far. The hot in-place process in Queensland involves a recycling unit which is known as the Wirtgen remixer. This machine can remove, modify and relay damaged asphalt surface in a single operation. Many reasons have been put forward for insitu asphalt recycling. These include increasing costs of new pavement materials, shortage of good quality aggregates, haulage costs to and from quarries, conservation of natural resources, energy conservation and geometric limitations of existing urban roads. The Department of Main Roads, Queensland has been extensively involved in the design, construction and performance monitoring of hot in-place asphalt recycling treatment. Design and construction methods are being constantly reviewed in order to obtain a quality end product. Performance test results to date have given us the insight into the advantages and disadvantages of this technique. This paper highlights the Departments experience in the areas of design, construction and performance of the hot in-place asphalt recycling rehabilitation technique.