Prediction of the scalar modulus for asphalt concrete based on micromechanics

The scalar modulus (SM) is temperature-dependent and can isolate temperature effects from time/frequency effects. A micromechanics-based model is developed to predict SM directly from component characteristics by combining a binder aging law with a binder rheology–to–modulus mapping and a composite-integrity (CIS) homogenization. Air-void and aggregate mechanical properties are considered constant; binder behavior is temperature- and aging-dependent. The binder input to CIS is the magnitude of dynamic modulus at 10 Hz, and two calibrated integrity exponents map this frequency-specific input to the relaxed (frequency-independent) mixture level. The resulting SM is identified with the relaxed modulus of the mixture, enabling direct use in pavement response calculations and reducing testing time and cost. Model parameters are calibrated and verified against comprehensive datasets spanning multiple aggregate types, gradations, binders, aging states, temperatures, and test conditions. The model predicts SM with high accuracy and yields strong empirical relations between SM and key performance indicators—creep-compliance rate, dissipated creep strain energy, and fracture energy—with distinct trends for modified versus unmodified binders. Because SM is formulated explicitly in the relaxed state, it serves as a temperature-dependent reference modulus consistent with a relaxed correspondence framework and can replace Schapery-type correspondence choices in subsequent viscoelastic analyses.