In-place recycling and retreatment of pavement materials

Recycling road materials is an absolute necessity in terms of environmental protection: saving natural resources (aggregates), natural spaces (landfills) and energy, and reducing greenhouse gases.

All road materials are recyclable. They can be reused either at the plant or in situ. In-place recycling brings additional transport savings.

There is a whole range of recycling techniques, the choice of which will depend on the nature of the material to be reused, its processing method and the final destination of the resulting product.

The degree of penetration of recycling operations varies widely from country to country, and even from region to region. In Northern Europe, recycling is virtually systematic. In the United States, the situation varies greatly from state to state. Whatever the country, recycling developed earlier and faster in highly urbanized areas, faced with the increasing remoteness of quarries and the scarcity of landfill sites.

In France, recycling and reprocessing began in the late 1970s, following the first oil crisis. Development was then rather slow, due to the abundance of quarries and asphalt plants. However, the situation began to change significantly in the 1990s, with the introduction of stricter legislation, in particular prohibiting the landfilling of materials other than "ultimate" (non-reusable) waste, and requiring the recovery of existing materials in pavements (law of July 13, 1992). Since then, rising energy and bitumen prices have done the rest, so that today, recycling road materials is almost systematic. On the other hand, as we'll see below, their recovery is not yet at its maximum.

In-place recycling is generally less "industrial" than in-plant recycling: a certain heterogeneity of materials may persist, and mixing quality is generally lower. On the other hand, it is particularly beneficial in terms of sustainable development. Finally, as we shall see, the range of in-place processing machines is very broad, from rustic machines to highly sophisticated multi-purpose machines.

This dossier completes [C 5 620] , which deals with recycling in power plants.