The effect of different aging conditions and strain levels on relationship between fatigue life of asphalt binders and mixtures

Abstract

Hardening, the most important cause of aging, can lead to different pavement failures. The first goal of the present research was to appraise the impact of different aging conditions and strain levels on fatigue behavior of asphalt binders and mixtures using frequency sweep, linear amplitude sweep (LAS), and four-point bending (4PB) fatigue tests. The second aim of this study was to assess the impact of aging on the correlation between fatigue life of asphalt binders and mixtures. The outcomes of the LAS test demonstrated that increasing the aging severity at low strain levels improved the asphalt binder fatigue life. However, aging reduced binders fatigue life when subjected under higher strain levels. The rheological master curves showed that aging had a remarkable influence on the viscoelastic characteristics of the binders at low-frequency ranges, and the aging influence on rheological characteristics of the binders decreased at high-frequency ranges. The polymer modified binders (PMB) performed better in terms of fatigue performance under higher loading frequencies and lower strain. However, by reducing the loading frequency and increasing the strain level, the degradation of the polymeric network led to a reduction in the fatigue performance of the PMB. The outcomes of the 4PB fatigue test indicated that aging reduced the fatigue life of neat and modified mixtures at high strain levels, while it had not any remarkable impact on the fatigue behavior of modified mixtures at low strains. The ANOVA analysis showed that aging and strain levels had a substantial influence on the fatigue life of asphalt mixtures with a significance level of 0.05. The correlation between the fatigue life of binders and mixtures demonstrated that applying aging on mixtures increases the accuracy and correlation coefficient between the fatigue life of binders and mixtures.