Energy-Based Mechanistic Approach to Characterize Crack Growth of Asphalt Mixtures

Abstract

Fatigue cracking is a common distress in asphalt pavements, but most existing models to predict its growth are generally empirical or phenomenological in nature. To fill this gap, this paper aims at developing an energy-based mechanistic approach to model the fatigue crack growth in asphalt mixtures. The core of this approach is establishing the energy balance equations between the apparent energy of the bulk specimen and the true energy of the intact material. A controlled-strain repeated direct tension (RDT) test is used to generate fatigue cracking damage in asphalt mixtures. The true stresses, true strains, and true pseudostrains are simulated through the force equilibrium and energy balance equations. The true stress in a damaged asphalt mixture is found to be the driving force for crack growth; the crack growth in turn aggravates the localization of the true stress/true strain. The ratio of the true stress and the apparent stress in a damaged asphalt mixture is used to calculate the damage density. The evolution of the damage density with repeated loading demonstrates the development of fatigue cracking in the asphalt mixture. In addition to modeling fatigue cracking in asphalt mixtures, the energy-based mechanistic approach developed in this paper can be used with a wide range of tests to predict crack growth of different types of materials because of its mechanical nature.