Fatigue and Stiffness Evaluations of Reclaimed Asphalt Pavement in Hot Mix Asphalt Mixtures

The recycling of existing asphalt pavement materials produces new pavements with considerable savings in material, money, and energy. Understanding the ability of an asphalt pavement containing reclaimed asphalt pavement (RAP) to resist fracture from repeated loads is essential for the design of hot mix asphalt (HMA) mixtures. However, reaching a better understanding of fatigue behaviors of these pavements continues to challenge researchers all over the world, particularly, as recycled materials with more complex properties are being used in HMA pavements. This study explores the utilization of the conventional fatigue analysis approach in investigating the fatigue life of asphalt mixtures containing RAP. The fatigue beams were made with two asphalt binders, two aggregate sources, four RAP contents (0 %, 15 %, 25 %, and 30 %), and tested at 5 and 20°C. A total of eight mixtures was evaluated and 64 fatigue beams were tested in this study. The test results indicated that the addition of RAP, as expected, increased the viscosity, G^∗sinδ, and creep stiffness values while reducing the m-values. However, no obvious trends were found for stiffness and fatigue life of mixtures as the RAP content increased. Statistical analysis results indicated that for binders and mixtures containing 30 % RAP, the utilization of softer binder significantly decreased the viscosity, G^∗sinδ, and creep stiffness values; however, there were no significant differences in the stiffness and fatigue life values of these mixtures.