A micromechanics-based computational model and testing protocols to characterize damage-dependent mechanical responses of asphalt mixtures in flexible pavements

This paper presents a micromechanics-based computational model and testing protocols to characterize damage-associated mechanical responses (such as evolution of microcracks, structural degradation, and fracture failure) of asphalt concrete mixtures in flexible pavements. Based on micromechanics concepts, this approach employs directly-measured material and fracture properties of mixture constituents to predict damage-dependent behaviour of global scale asphalt concrete mixtures. The presented methodology is expected to provide an increase in predictive power and a significant savings in experimental costs and time over traditional phe-nomenological approaches due to its innovative features including: (1) nonlinear inelastic material behavior, (2) rate-dependent microscale fracture-damage, (3) small-scale material characterization that reduces experimental effort and complexity, and (4) non-destructive image techniques to provide real heterogeneity of asphalt concrete mixtures. Experimental protocols to measure fundamental material properties and fracture-damage characteristics of mixture constituents are introduced, and testing results are presented. Measured mixture constituent properties are then incorporated into constitutive models and micromechanical finite element analyses to ensure that the measured fundamental properties of mixture constituents are key factors controlling overall damage-induced performance of asphaltic composites. The outcomes of this study lead to establishing the linkage between the properties of the mixture constituents, microstructure distribution such as mixture heterogeneity, damage localization, and global structural performance.