A study on fatigue modeling of hot mix asphalt mixtures based on the viscoelastic continuum damage properties of asphalt binder

• Asphalt binders’ integrity is well correlated to fatigue of asphalt mixture.
• The contribution of damage rate of binder to mixture fatigue is investigated.
• A fatigue model for mixture is suggested in terms of VECD analysis of binder.

Asphalt mixtures are time, temperature and stress dependent and categorized as viscoelastic materials. A wide range of models have been proposed to characterize the fatigue behavior of asphalt mixtures. In this study continuum damage theory is used to characterize fatigue properties of asphalt binders and their effects on mixture’s fatigue resistance. Neat, polymer modified and nanoclay modified bitumens were tested using linear amplitude sweep test. Four point bending beam fatigue tests were conducted on mixtures made with these binders at different loading rates namely 400, 600, 800 and 1000 micro-strain. Results showed that a strong correlation exists between the viscoelastic parameter of binder’s integrity and the fatigue resistance of asphalt mixtures. Furthermore, a phenomenological fatigue relationship was introduced which is a function of the strain loading of the mixture as well as the viscoelastic continuum damage properties of the binder phase in the mixture. The proposed model can be used as a surrogate to time consuming beam fatigue tests.