Investigation of Diffusion-Controlled Oxidative Aging in Asphalt Mixture

摘要

Aging of asphalt mixtures is an irreversible process, which may negatively affect the durability of flexible pavements and eventually increases the maintenance cost. Aging depends not only on binder physicochemical properties but also on the mixture morphology, which is a combination of aggregate packing, porosity, air void distribution, and their interconnectivity. Prediction of the impact of binder's aging on the behaviour of asphalt mixtures without considering the influence of mixture morphology may lead to erroneous conclusions on the potential performance of the mix. This paper investigates the long-term field aging of asphalt mixtures by incorporating mixture morphology. A computational analysis of diffusion-reaction process has been conducted by implementing fundamental mechanism of aging and conducting a parametric sweep of the morphology. To investigate the aging gradient along the depth of asphalt mixture, diffusion-controlled oxidative aging on one dense-graded and one open-graded field asphalt concrete core were investigated. To validate the model, a non-linear regression analysis was performed using a large field data set. The proposed model based on the mixture morphology information was able to predict the aged viscosity better than the existing model. As mixture morphology is controllable, having an insight into how the morphology parameter would influence the mixture's aging susceptibility can be of great value to its design.