Low Temperature Cracking Prediction with Consideration of Temperature Dependent Bulk and Fracture Properties

ABSTRACT Thermally induced cracking due to low temperature is a prominent pavement failure mechanism in colder regions. In recent years significant advances have been made in laboratory characterization and computer simulation of asphalt pavements in the context of low temperature cracking. With the advent of fracture energy test protocols that provide fundamental material separation characteristics, it is now possible to accurately simulate crack initiation and propagation in asphaltic materials through use of fundamental fracture mechanics tools in a practical manner. A cohesive zone fracture model allows for accurate representation of the quasi-brittle nature of asphalt concrete by modelling the highly nonlinear fracture process-zone ahead of the macro crack. Several authors have previously demonstrated that the asphalt material bulk and fracture properties vary significantly with temperature. While improvements in cracking prediction accuracy has been obtained through the use of temperature dependent bulk properties, the effect of temperature dependence on fracture properties also needs to be considered to achieve even more realistic simulation results. In the current study, computer simulation models have been proposed with temperature dependent bulk and fracture properties. These include: viscoelastic relaxation moduli, coefficient of thermal expansion and contraction, and fracture energy. A series of verification cases are presented to demonstrate the veracity of the numerical models developed and implemented. Five pavement sections from the MnROAD test site are simulated using the proposed model. The results are compared with previously reported simulation results as well as field data. The proposed model yields a better match between the simulated results and the field observations.