Predicting Viscoelastic Response and Crack Growth in Asphalt Mixtures with the Boundary Element Method

It has long been accepted that cracking of hot-mix asphalt pavements is a major mode of premature failure. Many state agencies have verified that pavement cracking occurred not only in fatigue cracking, in which a crack initiates from the bottom of the asphalt layer, but also in other modes such as low-temperature cracking and the more recently identified top-down cracking. To improve current pavement designs and the cracking resistance of mixtures, it is necessary to understand the mechanisms associated with crack initiation and crack growth in hot-mix asphalt mixtures. However, the complexity of the problem and the lack of simple-to-use analysis tools have been obstacles to a better understanding of hot-mix asphalt fracture mechanics and the development of better hot-mix asphalt fracture models. Until today, the well-known finite element method has been the primary tool used for modeling cracks and their effects in mixtures and pavements. Unfortunately, it is both complex and numerically intensive for fracture mechanics applications. The displacement discontinuity boundary element method is presented, which is a numerical method that has been very successful in many other engineering fields, as a potential method for modeling cracking in hot-mix asphalt mixtures and pavements. A series of examples are provided to illustrate the effectiveness of the method in dealing with cracks, crack propagation, and visco-elasticity in hot-mix asphalt. It was concluded that the method was easy to use, resulted in accurate solutions, required minimal computation time, and significantly simplified the modeling of crack-related problems.