Highlighting of the viscoelastic behaviour of interfaces in asphalt pavements – a possible origin to top-down cracking

Abstract

Top-down cracking (TDC) is known to initiate and remain near the surface of bituminous pavements. The aim of this paper is twofold: (i) show experimental evidence of the viscoelastic behaviour of interface in asphalt pavements under some temperature conditions and (ii) show that taking into account such a behaviour could provide an explanation to the mechanism involved in the initiation of TDC. This paper documents the methodology used to investigate the behaviour of the upper interface from experimental tests. The mechanical response of the experimental pavement is evaluated using three models: (1) the elastic model, (2) the Huet–Sayegh viscoelastic model to account for the behaviour of asphalt layers and (3) same as 2, but with additional very thin viscoelastic layers to represent interfaces between the asphalt layers. The software ViscoRoute 2.0© is used to evaluate the stresses and the strains at different depths of the pavement. The comparison between the experimental results and the models clearly shows that model 3 is that yields the best fit. This model shows that significant tensile stresses and strains occur near the surface and at the interface between two asphalt layers. The transposition of the viscoelastic behaviour of interfaces to real traffic conditions could explain TDC as one of the damaging modes of asphalt pavements.