Asphalt pavements are easy to recycle. The carriageway can be excavated or scarified, the material crushed and re-used either hot or cold. The most environmental method is cold recycling since there is no need for the material to be heated. Hot recycled material is mainly used as wearing course/roadbase on roads carrying medium to high traffic loads, while cold and warm material is used on low to medium traffic load roads. In cold and warm recycling, the character of the material is partly altered depending on the new binder used. The intention at present is that almost all asphalt pavement material will be recycled in the future. The following are unique or different for recycling: (1) variation in recycled material; (2) interaction between new and old binder and water content; (3) consistency is very significant; (4) binder and aggregate are not so well defined; (5) material has flexible and self-healing properties; (6) variable and sometimes unexpected results; (7) lack of specifications and test methods; and (8) the technique is resource economic and environmental. R&D is in progress, chiefly regarding cold recycling and test methods for characterisation of cold asphalt material, mechanical properties and durability. Work is also in progress on mix specifications. Most failures are due to use of too little or too much binder.
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