Base course with hard paving grade and wearing course with multigrade bitumen: an innovative couple to fight the rutting and reduce costs of road maintenance on the long-term. Experiments in France and Belgium.

Finalized in the 1980's, the new multigrade bituminous binders became widespread in the 1990's to most of the European producers of bitumen and were the subject of many papers. A lot of road trials of technical demonstration were realised with multigrade bitumen, showing the evidence of the major interest of these products with regard to the normal paving grades, namely a decrease by two of the rut globally registered on courses for the same formulation of bituminous mix, including same aggregates. These bitumens, generally 35/50 graded, sometimes 20/30 even 50/70 became of a common use within the European Union. All these innovations allow to significantly reduce the quantities of materials to be used in the construction and especially to decrease the costs of maintenance, due to an increase of the longevity of both the base and the wearing courses, generally some years. Preliminary results of an experiment realised in the LCPC in France and practical examples of construction sites realised in Belgium on trials with high mechanical constraints such as service stations, and using the innovative couple "base course with hard paving grade and wearing course with multigrade bitumen", are described in this paper. For the covering abstract see ITRD E135448.