Numerical Simulation of the Cracking Behavior of Asphalt Mixtures

An understanding of the cracking behavior of hot mix asphalt mixtures provides an important basis for the development of mixtures with improved cracking resistance and pavement cracking performance models. This paper describes the use of random assemblies of displacement discontinuity boundary elements to model the behavior of asphalt mixtures. These random assemblies of boundary elements form particles of varying sizes, which are arranged to simulate the discrete nature of mixtures. To account for the aggregate and mastic properties, each particle is connected to other particles by specifying the cohesion, friction, and tensile properties of the material between particles. The crack initiation and crack growth are simulated using two distinct crack growth laws, based on sequential and parallel crack growth rules. Cracks are allowed to grow along particle boundaries. A series of simulations were performed of the load-deformation and cracking behavior of a typical 19.0-mm nominal maximum aggregate size mixture commonly used by the Florida Department of Transportation. The effects of crack growth rules, particle size, and localization to geometric effects were studied. In summary, the method presented appears to provide a valuable tool for studying the mechanistic behavior of asphalt mixtures.