Laboratory and ALT-Evaluation of high stiffness underlayers with high percentage of re-use as developed in the NR2C- project

New Road Construction Concepts (NR2C) is a project of FEHRL supported by the European Commission under the Sixth Framework Programme. This project aims at developing perspectives and specific innovations in different transport areas. One of the ideas concerns the development of high performance underlayers with high percentage of reclaimed asphalt. Three different mixes were designed, optimized and compared, namely with 0 %, 25 % and 40 % reclaimed asphalt. After an extensive laboratory study in BRRC, the selected mixes have been further studied in a full-scale ALT facility in LAVOC. During these tests, resistance to fatigue at 15 °C and also low temperature behavior with cycles between 2 °C and -7 °C have been investigated by applying 12 tons axle loads. In addition to the ALT, wheel tracking tests, tests on cores as well as on big slabs with a controlled temperature gradient have been performed on material taken from the ALT tracks. Moreover, a specific binder analysis has been carried out in order to analyse the evolution of the binder and mix properties. The most important conclusion from this work is that no negative effect, due to the use of a high percentage of reclaimed asphalt, has been observed in this study. However, key parameters such as the RA properties and mix design as function of the RA properties require special attention.