Relationships between 3D linear viscoelastic properties of bitumen, asphalt mastics and asphalt mixtures using micromechanical models

In this paper, micromechanical models are used to predict the 3D viscoelastic behaviour of asphalt mixtures (with volume fraction of aggregate particles up to 87%) from the mechanical properties of their constituents. To fulfil the objective of study, complex modulus tests are conducted on bituminous materials at three different scales: bitumen, asphalt mastics and asphalt mixtures. The volume fraction of particles varies from 0% (bitumen) to 15%, 25%, 35% (asphalt mastic) and up to 87% (asphalt mixture). In the experimental program, complex modulus of bitumen, asphalt mastic and asphalt mixtures at different temperatures, frequencies are measured. For asphalt mixtures, measurements of complex Poisson's ratio are also performed. The rheological model 2S2P1D is used to simulate the 3D viscoelastic behaviour of tested bituminous materials. From the experimental results and simulations, two micromechanical models (self-consistent and generalized self-consistent model) are used to predict the complex modulus and complex Poisson's ratio of asphalt mixtures. The obtained results show that both micromechanical models give the good prediction of complex modulus for asphalt mastic where the volume fraction of aggregate particles is lower than 35%. At asphalt mixture scale where the volume fraction of particles is up to 87%, only simulation using the generalized self-consistent model can show good results. The prediction using the generalized self-consistent model at the mixture scale can be applied for both complex modulus and complex Poisson's ratio. In addition, the prediction of complex modulus and complex Poisson's ratio of asphalt mixtures becomes better when the asphalt mastic instead of bitumen is considered as viscous matrix.