This chapter describes some of the possible modelling approaches for both predicting and controlling the key mechanical properties of Recycled Aggregate Concretes. The chapter is organised in three sections in which the different models applied during the research are described. Particularly, in the last section an innovative modelling methodology is proposed for the case of RAC. The proposed formulations should be considered as a novel conceptual approach capable of considering the key physical and mechanical features characterising the structural behaviour of resulting concrete made out with Recycled Concrete Aggregates