Crack modeling of asphalt mixtures using nonlinear viscoelastic cohesive zone (NVCZ) to assess the influence of different fillers in the material's fracture resistance

Abstract

Micromechanical numerical models have become an important tool in the study of asphaltic pavements given its numerous advantages in comparison to analytical, semi-empirical and/or completely experimental approaches. Thus, this study presents a framework to predict the behavior of bituminous composites considering viscoelasticity and fracture resistance based on nonlinear viscoelastic cohesive zone (NVCZ) model. The NVCZ model is able to predict the entire fracture process, from crack nucleation, initiation, and propagation in mixture microstructure. To examine the NVCZ model, two fine aggregate matrix (FAM) mixtures containing different fillers (hydrated lime and steel slag) were evaluated experimentally and compared to the numerical results. FAM material linear-viscoelastic properties and fracture parameters required as input for the numerical modelling were experimentally obtained. Linear-viscoelastic properties were obtained by performing frequency sweep tests and the required NVCZ parameters were obtained by an experimental-numerical calibration procedure using semi-circular bending (SCB) laboratory tests coupled with finite element numerical simulations. To validate the model, microstructural numerical simulations of the indirect tensile strength test (IDT) were conducted and compared to experimental results. Numerical modeling results agree well with laboratory testing results. The results of this research imply that the NVCZ model is promising to evaluate the cohesive fracture resistance of different material constituents in bituminous composites with significant savings in experimental costs and time.