New method to obtain viscoelastic properties of bitumen blends from pure and reclaimed asphalt pavement binder constituents

The main issue with asphalt pavement recycling is the assessment of the influence of aged bitumen in reclaimed asphalt pavement (RAP) material on viscoelastic properties of a blended binder in the final mixture. Blending charts or empirical laws, such as the "log-log" rule, are currently used to estimate grading parameters for material characterisation. However, a true prediction method of linear viscoelastic properties is still missing. The presented study is part of a wider ongoing research effort in the framework of a Ph.D. thesis, in collaboration between University of Lyon/Ecole Nationale des Travaux Publics de l'Etat (ENTPE), EIFFAGE Travaux Publics (ETP) and Beyond Petroleum. The paper focuses on the influence of the RAP-extracted binder content on viscoelastic properties of bitumen blends obtained from different asphalt binders. Three unaged bitumens were blended with a binder extracted from a well-known RAP material in different proportions (20%, 40% and 60%) for a total of 13 different bitumen blends. Complex modulus Dynamic Shear Rheometer tests were performed on binders at the ETP Research Center. Experimental results were modelled by using the 2S2P1D model, previously developed at ENTPE. A method to estimate viscoelastic properties of bitumen blends over the whole range of frequency and temperature is proposed.