Two-way coupled multiscale modelling and comparison with field observations of fatigue cracks in bituminous pavements

Fatigue cracking in bituminous pavements has long challenged the pavement engineering community, prompting approaches ranging from phenomenological to mechanistic. This study uses a two-way coupled multiscale (TWCM) modelling approach for effectively addressing fatigue cracking by concurrently linking critical length scales within the pavement structure. For a simple, feasible and practical development, the method integrates two common, widely-used laboratory-scale experiments on asphalt concrete (AC) mixtures—dynamic modulus and semi-circular bending fracture—with finite element modelling. The complex viscoelastic fracture behavior of AC mixture within pavements is modeled by employing the nonlinear viscoelastic cohesive zone that can effectively capture rate- and mode-dependent crack initiation and propagation within heterogeneous AC mixture and their direct linkage to the degradation of structural integrity within pavements. To demonstrate the scientific rigor and predictive capability of TWCM modelling, it was applied to simulate the fatigue cracking performance of instrumented pavement sections where two AC mixtures had similar volumetric characteristics but different component properties. Comparison of modelling results with field performance demonstrates the method's capability and potential as an advanced tool for pavement engineering practice, supporting more optimized selection and evaluation of paving materials, a more mechanistic design of materials/structures, and lower-cost maintenance of pavements.