Investigating the influence of fine RAP on bituminous mixtures at the mastic scale: viscoelastic analyses and micromechanical modelling

This paper studies the potential effects of Reclaimed Asphalt Pavement (RAP) fine particles on bituminous mixtures by means of a laboratory investigation performed at the mastic scale. Bituminous mastics, characterised by a constant filler to bitumen volume ratio, were prepared by combining virgin filler and virgin bitumen with several dosages of RAP fine particles. The influence of RAP type was evaluated by employing two RAP products supplied by different sources. The rheological behaviour of the mastics was investigated by means of oscillatory tests carried out with a dynamic shear rheometer. The time-temperature superposition principle and the generalised self-consistent scheme (GSCS) micromechanical model were used to explore the role played by RAP at the mastic scale. Results indicate that the adopted experimental and modelling approach allows a proper assessment of the effects of RAP on the linear viscoelastic properties of mastics and of the degree of blending occurring between virgin and RAP binder.