In last decades the use of Reclaimed Asphalt Pavement (RAP) materials in asphalt mixtures has seen a significant expansion for economical and environmental reasons. Nevertheless, there are still two important issues which have not been effectively solved: the first regards the characterization of the aged binder contained in RAP; the second concerns the ability to predict the performance of asphalt mixture composed with high RAP content. Regarding the first problem, the current methods are based on extraction and recovery of the RAP binder using solvents; however, these methods are not fully accurate since they can alter the rheological properties of the binder. For this reason, in the present work, a new procedure to back-calculate the rheological properties of the aged binder contained in RAP materials and of the blends composed with fresh and RAP binder, was developed. This is based on DSR tests performed on mortars, composed by mixing the fine fraction of the RAP aggregate with virgin binder. Using the Nielsen model, specifically adapted to asphalt mortars’ case and the Voigt model, the rheological properties of RAP binder can be back-calculated from mortars tests. The present procedure has two advantages: the aged binder contained in RAP is tested as it is after the milling process, avoiding any further treatments, while the testing campaign is centered on the mortar phase, which is one of the most important phases governing the properties of the mixtures and, therefore, the performance of asphalt pavements. Regarding the second problem, a multi-scale approach based on rheological model (2 Spring, 2 Parabolic Elements, 1 Dashpot, 2S2P1D model) and on empirical models (Hirsh e Witczak models) was developed to predict the rheological properties of asphalt mixture containing RAP materials, starting from tests on asphalt mortars and taking into account the grading of the aggregates and the volumetric composition of the mixtures. This methodology allows to make reliable previsions for both the problems addressed, as demonstrated by the results of the validation tests carried out in this doctoral thesis. In addition, the present research provides innovative solutions to address some of the issues which are currently of particular importance for the purposes of extending the use of RAP material in the production of asphalt mixture.