Evaluating Fatigue-Cracking Resistance of Asphalt Binders in a Standardized Composite Using Continuum Damage Theory

Abstract

Several different modifiers are increasingly being used to improve the performance of asphalt binders (e.g., polymers) or to promote environmentally friendly technologies (e.g., warm-mix asphalt, ground tire rubber, and organic waste). In such cases, it is important to evaluate the inherent improvement in engineering properties and damage resistance of the asphalt binders while being subjected to a state of stress that is similar to full asphalt mixtures. The first part of the paper presents a review of the literature that investigates the state of stress of the asphalt binder in an asphalt mixture as well as the test methods that have been used to achieve this state of stress experimentally. The second part of the paper presents a test method by which the fatigue-cracking characteristics of four different asphalt binders with similar true temperature grades were evaluated. Composite test specimens were fabricated using asphalt binders and glass beads with a specified gradation. The viscoelastic and fatigue-cracking characteristics of the binders were measured using the glass bead-binder composite specimens in a dynamic shear rheometer at an intermediate temperature. Results were analyzed using viscoelastic continuum damage theory. Damage evolution in the glass bead-binder test specimens used in this study was qualitatively very similar to the damage evolution in full asphalt mixtures using the same binders.