Field-scale production validation of Warm Mix Asphalt containing Crumb Rubber for motorway porous wearing course

Warm Mix Asphalt (WMA) technology in combination with crumb rubber (CR) from end-of-life tires (ELTs) can lead to a sustainable low environmental impact solution, while enhancing mechanical and acoustic perfor-mance of asphalt pavements. As part of a broader project, including a preliminary laboratory investigation, this research aims at evaluating the technical feasibility of WMAs modified with CR by dry process for porous wearing courses. Large-scale production and field trial on motorway section were conducted to assess the per-formance of the selected mixtures according to the Technical Specifications for the Italian motorway network. The experimental investigation included volumetric and workability analyses, mechanical tests and surface characterization on both laboratory specimens and cores taken from the field trial. The results show that when the CR content is lower than a critical amount no specific precaution has to be undertaken at production plant and during lay-down activities in order to guarantee satisfying workability, mechanical and surface properties.