Experimental evidence of the viscoelastic behavior of interfaces in bituminous pavements-An explanation to top-down cracking?

Abstract

Top-down cracking is known to be initiated near the surface of the asphalt layers. The aim of this paper is twofold: (i) to show experimental evidence of the viscoelastic behavior of interface in asphalt pavements under some temperature conditions, (ii) to show that the integration of such a behavior could provide an explanation of the mechanism involved in the initiation of bottom-up and top-down cracking. This paper documents the methodology used to investigate the behavior of the upper interface from experimental tests carried out at the IFSTTAR’s track facility. The mechanical behavior of the experimental pavement is evaluated using three different models: (1) elastic model, (2) Huet-Sayegh viscoelastic model to account for the behavior of asphalt layers, and (3) same as 2, but with additional very thin viscoelastic layers to represent interfaces between the asphalt layers. Computations are performed for two load configurations using software ViscoRoute 2.0© to evaluate the stresses and strains at different depths of the pavement for the 3 models. The comparison between the test track results and the models clearly show that model 3 is that yielding 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 behavior of interfaces to real traffic conditions could explain top-down cracking as one of the modes of failure of asphalt pavements.