Hot asphalt recycling in cold climate: performance-based mixture design and a test section in the Swiss Alps

The use of high reclaimed asphalt pavement (RAP) content in the production of hot asphalt mixtures increases the risk of pavement cracking, especially in locations with cold climate and high temperature fluctuations. Here we used a performance-based mixture design approach to prepare three plant-produced hot asphalt mixtures for base, binder and foundation courses containing between 60% and 85% RAP and paved them at 1900 m altitude in the Swiss Alps. The mixture performance-based test and road core test results demonstrated that it is possible to ensure the required mixture performance even when using high RAP content so long as the homogeneity of RAP is ensured. The conventional mixture quality control requirements were fulfilled as well. As a result of the research, recommendations for designing mixtures containing high RAP content for high altitude roads are proposed.