Performance assessment of warm open-graded mixtures containing 25% reclaimed asphalt for wearing course of heavy-duty pavements

In recent years, the growing attention of public opinion towards environmental issues has prompted researchers to find valid and performing alternatives to traditional hot-mix asphalt (HMA) and related production process. In this regard, warm-mix asphalt (WMA) technology combined with the use of reclaimed asphalt (RA) seems to be a promising and eco-friendly solution, due to its eco-sustainability and well-proven economic benefits in addition to better working conditions. On the other hand, the combination of WMA and RA technologies could lead to drawbacks in service performance on roads with high volume of heavy traffic, especially in case of open-graded mixtures for wearing course which, in turn, increase road safety and promote traffic noise absorption. In this framework, the present research describes first, a laboratory investigation on WMAs with 25% RA for open-graded wearing course to verify their use on the Italian motorway network, and then the validation of the selected mixture produced at the asphalt plant. The results of experimental investigation have highlighted satisfactory volumetric and mechanical properties according to the current Italian motorway technical Specifications. In addition, the analysis of the in-plant produced mixtures also has proved the technical feasibility of large-scale production of WMAs with RA for open-graded wearing course.