This paper describes research carried out internationally and in New Zealand examining the potential use of different waste and recycled materials in road construction. A number of different wastes including scrap tyres, glass, blast furnace slag, steel slag and plastics, have been investigated in Europe, the US and Canada to assess their potential for use as different roading materials. The results indicate that there is a high potential for the use of these materials in road construction, road performance is not compromised when wastes are used according to specifications, and costs of road construction can be reduced. In New Zealand, research is currently underway to examine the potential for use of some locally available wastes in road construction. The results, to date, indicate that there is a wide scope for the use of such materials. However, a number of materials have not been investigated and further research on suitability, economics and availability of materials is still required (a).
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