Investigation into the impact of the use of 2D/3D digital models on the numerical calculation of the bituminous composites’ complex modulus

Abstract

The aim of this article is to study the impact of two- or three-dimensional modeling on the prediction of the complex modulus of bituminous materials using a finite element method through a biphasic approach. The bituminous composites considered are mastic and mortar. These materials are treated as biphasic materials composed of a bituminous matrix and a granular skeleton which forms the network of inclusions.The viscoelastic properties of the matrix and the elastic properties of the aggregates are the input parameters for the heterogeneous numerical models. A general form of Maxwell’s model is used to describe the viscoelastic behavior of the matrix. Random inclusions of varying size and shape are generated in order to construct the granular skeleton. The two- and three-dimensional digital models are submitted to different sequential loadings with the aim of constructing the numerical complex modulus curve of the bituminous composite under study. The two-dimensional (2D) numerical results are lower than those obtained using a three-dimensional (3D) calculation, and the overall numerical results are situated under those obtained by an experimental approach. The resulting gap shows the weakness of the 2D model used to describe the mechanical behavior of this type of material, which is largely influenced by the heterogeneity of the mechanical properties of the two phases present and by the interlocking of aggregates. Finally, a correlation is established between the spatial dimension of the digital model as well as the individual mechanical properties of each phase and the dynamic modulus of the composite under study.