Design and Performance of Hot Mix Asphalts with High Percentages of Reclaimed Asphalt: Approach followed in the Paramix Project

The use of reclaimed asphalt pavement (RA) in new asphalt pavements can provide important economical savings, while reducing the negative environmental impact. The European research project PARAMIX aims to improve the techniques for hot mix recycling in plant and cold mix in situ recycling, so as to increase the amount of reclaimed asphalt and develop competitive road pavement rehabilitation techniques. This paper deals with the design of hot mix asphalts for the project. The different phases in the design process are described: the characterization of the reclaimed asphalt and the new material components, the volumetric mix design procedure and the laboratory study. Two types of mixes were considered: stone mastic asphalt and asphalt concrete. The percentages of reclaimed asphalt in these mixes were high: up to 30 % for the SMA and 50% for the asphalt concrete. The results of the performance tests show the feasibility to design and optimize good quality hot mix asphalts with a high percentage of reclaimed asphalt. The asphalt mixes have been applied on an experimental road.