Influence of Chemical Constituents of Asphalt Binders on Their Rheological Properties

The goal of this study is to investigate the chemical constituents and rheological properties of three different binders used in the State of Qatar. Binders were designated as WL (source 1, low density), WH (source 1, high density) and AH (source 2, high density). Binder composition analysis was carried out using the saturates, aromatics, resins and asphaltene determinator (SAR-AD) technique. The percentages of saturates, aromatics, resins and asphaltenes were measured, and from those, the total pericondensed aromatics (TPA), absorbance aging index (AAI), and colloidal instability index (CII) were obtained and their relationship to rheological test results was investigated. In the rheological investigation, the linear viscoelastic properties of these binders were evaluated using a frequency sweep test. The rutting characteristics were evaluated using the percentage of recovery and non-recoverable creep compliance values from the multiple stress creep and recovery (MSCR) test, while the fatigue resistance was assessed using the linear amplitude sweep (LAS) test. The WL binder was found to have the highest stiffness, which is associated with the highest TPA content. From the MSCR test, the AH binder had the lowest rut resistance. This binder also had the lowest CII value, which represents the balanced chemical composition of this material. Out of the three binders, WH had the highest AAI value which is related to the least fatigue life as measured in the LAS test.