چكيده به لاتين
Abstract:
Fatigue cracking, resulting from repeated traffic loading, is a primary distress in asphalt pavements. The evaluation of fatigue properties of asphalt mixtures under different traffic loads and varying environmental conditions is of great importance in designing the flexible pavements. In the case of fatigue, it is well known that the distress usually initiates at the binder phase or the aggregate-binder surfaces especially at intermediate and high temperatures. Among, the binder phase possesses the highest contribution on asphalt mixture performance. It governs the viscoelastic behavior of the entire material and is responsible for the material’s strength and integrity. The most common device to evaluate the rheological properties of binders is the Dynamic Shear Rheometer. In this research study we used of DSR to characterize fatigue behavior of asphalt binders by applying strain-controlled tests and evaluating the number of cycles to failure. The Time Sweep test was used to investigate the viscoelastic fatigue properties of asphalt binders in terms of energy dissipation.
Since in both time sweep and flexural beam fatigue tests, the dissipated energy is an appropriate index for fatigue behavior of asphalt materials, investigation of any trend of this parameter in both asphalt binders and mixtures can provide valuable information on the energy dissipated during fatigue life of asphalt binders. In this research study, time sweep and four-point beam fatigue tests were conducted and the trends between energy parameters and fatigue lives of asphalt materials were studied by statistical analysis to estimate the fatigue life of both asphalt binder and mixture. Using the concepts of energy dissipation in fatigue life of asphalt binders and mixtures, the potential correlations between energy parameters of asphalt materials are presented. This suggests that it is possible to rank and calculate the fatigue life of an asphalt mixture by only conducting the time sweep test on the associated asphalt binder up to the 50th loading cycle which usually lasts only a few seconds.
Keywords: Hot mix asphalt (HMA), Asphalt binder, fatigue, Time sweep test, load four-point bending beam fatigue test
