Development of a fatigue index parameter, S_app, for asphalt mixes using viscoelastic continuum damage theory

ABSTRACT

Fatigue cracking is one of the major distresses in asphalt pavements. Engineers have used many methods, from sophisticated numerical simulations to experience-based knowledge, to address fatigue cracking and deliver pavements that perform well. One strategy that has become increasingly widespread is the use of a fatigue index parameter that identifies the cracking potential of asphalt mixtures independent of the pavement structure. The use of such indices allows pavement engineers to make quick and targeted decisions with regard to mix design, mix acceptance, and mix quality assurance. This paper proposes a new fatigue index parameter, S_app, which represents the damage capacity of a mixture and is based on the viscoelastic continuum damage theory. Unlike other indices, this new index considers the effects of both material toughness and stiffness. S_app was employed in this study to evaluate 105 different asphalt mixtures with varied design factors. The results indicate that S_app is able to distinguish the fatigue resistance of asphalt mixtures with varied properties, including different binder contents, binder performance grades, reclaimed asphalt pavement contents, types of binder modifier, air void contents, aggregate gradations, and aging levels. This paper also presents a set of recommended S_app threshold values for different expected traffic volumes.

KEYWORDS:

• Asphalt mixture
• fatigue
• index parameter
• viscoelastic continuum damage (VECD) theory
• traffic level
• S_app

Acknowledgements

This work was supported by the Federal Highway Administration (FHWA) under Grant DTFH61-08-H-00005.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Federal Highway Administration (FHWA) [grant number DTFH61-08-H-00005].