Viscoelastic Behaviour Characterization of a Gap-graded Asphalt Mixture with SBS Polymer Modified Bitumen

Abstract

A characterization of the linear thermo-viscoelastic behaviour of a gap-graded bituminous mixture with SBS-polymer modified bitumen and RAP aggregates is presented in this paper. A comparison was made, in terms of their viscoelastic behaviour, between this innovative mixture and two commonly used well-graded base-course French mixtures made with pure bitumen. The materials were also compared in terms of viscous dissipated energy. Complex modulus tests on cylindrical samples were performed for each mixture. The viscoelastic behaviour of the materials was modelled using the 2S2P1D (2 springs, 2 parabolic elements, 1 dashpot) constitutive model which was developed in the Laboratory of Civil Engineering and Construction (LGCB) of the ENTPE, University of Lyon. The tests results allowed validating the time-temperature superposition principle for the studied mixtures. Experimental and modelled complex modulus (|E*|) master curves were built for each material. The gap-graded mixture was found to present higher stiffness values at low frequency/high temperature conditions, lower viscous behaviour and lower values of viscous dissipated energy compared to the conventional mixtures. Complex modulus tests were also carried out on the polymer modified bitumen of the gap-graded mixture. A link between the viscoelastic behaviour of both binder and mixture could be established thanks to the SHStS transformation developed by the ENTPE team.