Micromechanics Modeling of Viscoelastic Asphalt-filler Composite System with and without Fatigue Cracks

Fatigue cracking of viscoelastic asphalt composite materials is one of the major distresses in asphalt pavements. To quantify the weakening effect of the fatigue cracks on the mechanical properties of the viscoelastic asphalt composite materials, this study takes an asphalt-filler composite system as an example, and micromechanics models are proposed by combining Eshbely's equivalent inclusion theory and Mori-Tanaka approach. Dynamic shear rheometer (DSR) tests are performed on the viscoelastic asphalt-filler composite systems with two volumetric contents of inclusion (10% and 27%) at different frequencies (0.1–100 Hz), temperatures (15℃, 20℃, 25℃) and strain levels (0.01%-0.1% for nondestructive DSR tests; 5%, 6%, 7% for destructive DSR tests). Results show that the predicted shear modulus results by a modified viscoelastic strengthening coefficient (VSC) model match with the test results at both low and high filler contents. Then a viscoelastic strengthening coefficient with fatigue cracks (VSC-f) model is proved being capable of accurately predicting the shear modulus for the viscoelastic asphalt-filler composite systems at different strain levels, temperatures, filler contents and damage levels. Both the VSC and the VSC-f model are derived to be dependent of loading frequency, temperature and filler content, but independent of strain level.