Multiscale Modeling of Damage Evolution in Viscoelastic Bituminous Mixtures Subjected to Cyclic Loading

This study presents a multiscale computational model and its application to predict damage dependent mechanical behavior of bituminous mixtures subjected to cyclic loading. Two length scales (global and local) are two-way coupled in the model framework by linking a homogenized global scale to a heterogeneous local scale representative volume element. Based on the unique two-way coupled multiscaling and the use of the finite element technique incorporated with the material viscoelasticity and cohesive zone fracture, the model approach can successfully account for the effect of mixture heterogeneity, material viscoelasticity, and damage accumulation due to cracks in the small scale on the overall performance of larger scale mixtures or structures. This step requires only the properties of individual constituents. To demonstrate the model and its features, bending beam fatigue testing of a bituminous mixture, which is composed of elastic aggregates and viscoelastic bitumen, is simulated by altering the mixture's constituent properties. The model clearly presents progressive damage characteristics with repetitive loading cycles and the analysis clearly demonstrates the sensitivity of the approach to constituent material properties. The multiscale model presented herein is expected to drastically reduce time-consuming and expensive fatigue tests, which, when performed in the traditional manner, require many replicates and do not define the cause of microstructural fatigue, damage, and failure.