PRESENT SITUATION OF THE TECHNIQUE USED IN DRYING AND MIXING PLANTS IN FRANCE

This article presents observations made on two types of drying and mixing plant (tsm ermont and drum mixer barber greene) in France, which show that it is possible to produce mixtures conforming to French standards and of equivalent quality to those produced in standard plants. The first experiments on a tsm ermont plant were carried out in 1976. Since then the French highways and Road Traffic Directorate has granted two permits of use to ermont tsm plants (February 1977) and to barber greene plants (February 1979), following in-situ test results studied by the LPC. Details are given of bitumen evolution, characteristics of the bituminous mixtures manufactured, mixing temperature and fulfilment of environmental requirements. Attention is drawn to critical areas of plant design. There exist some differences in operation according to the design of the plants, in particular the self-dedusting operation of the dryer-mixer. (TRRL)