An experience of rational mix design of recycled asphalt concretes on the basis of international guidelines

Within the pavements maintenance and construction, the increasing use of techniques for asphalt recycling in situ/plant needs a correct mix design process by which the regenerated asphalt can be raised to the required quality. In this paper the Authors performed an ex-perimental analysis on RAP (Reclaimed Asphalt Pavement), aimed to assess the reliability of the most recent mix design guidelines, which use a rational approach. The mix design of asphalt concrete with RAP was performed according to the procedures suggested by the SuPerPave® Mixtures Expert Task Group. Three different percentages of RAP (25, 35 and 50%) were adopted. The quantity of new bitumen to be added was established taking into account the old asphalt content and the required properties of final product. The critical temperatures of the binders (that added and the bitumen included in the RAP) were obtained by Rheological tests, using DSR and BBR devices. The performance of the recycled asphalt mixtures was assessed by laboratory procedures provided by the European Specifications.