Correlation investigation of fatigue indices of fine aggregate matrix (FAM) and asphalt mixture containing reclaimed asphalt pavement materials

Testing and evaluation of the Fine Aggregate Matrix (FAM) in terms of fatigue performance has gained popularity. However, the correlation of fatigue indices between FAM and asphalt mixture is unclear, especially for the asphaltic materials with Reclaimed Asphalt Pavement (RAP). Hence, this study aims to investigate the relationship of the fatigue performance between FAM and asphalt mixture incorporating with RAP and further validate the feasibility of optimizing the RAP mix design by FAM tests. The dynamic modulus test and direct tension cyclic test were employed to identify the viscoelastic and fatigue property of the RAP mixtures. The frequency sweep test and linear amplified sweep (LAS) test were conducted on the corresponding FAM samples. The fatigue index of the Superpave fatigue index (G*sinδ), pseudo stiffness at failure point (CF), and the LAS-based A parameter were obtained to quantify the fatigue performance of the FAM sample. Two fatigue indexes of the average reduction in pseudo stiffness up to failure (DR) and apparent damage capacity (Sapp) were used to describe the fatigue performance of the RAP mixtures. According to statistical analyses, the FAM indices exhibited relatively high discrimination. Analysis of correlation showed that strong correspondences were observed between DR or Sapp (mixture scale) and the A parameter (FAM scale). CF of the FAM showed a good agreement with the DR of the RAP mixture as well, but a fair agreement with Sapp due to different sensitivity to binder type and RAP content. The G*sinδ of the FAM presents a weak correlation with the fatigue indices of the RAP mixtures. Overall, both the CF and A parameter of FAM from the LAS test demonstrate a high potential to the prediction of the fatigue performance of asphalt mixture containing RAP at intermediate temperatures.