Comparative Evaluation of Methods for Removing Residual Mineral Fillers during Bitumen Extraction and Recovery Based on FTIR

Asphalt extraction and recovery are essential steps before characterizing components and properties of aged asphalt binders for recycling the reclaimed asphalt pavement (RAP). To accurately analyze the aged asphalt, it is essential to evaluate removal efficiency of residual mineral fillers during bitumen extraction and recovery. This study investigated three methods (filtration, gravitational sedimentation, and centrifugal sedimentation) to separate base asphalt and styrene-butadiene-styrene (SBS)-modified asphalt from the mineral fillers using trichloroethylene (TCE) solvent. The removal efficiency was quantitatively evaluated by the index of silicon–oxygen bond based on Fourier transform infrared spectroscopy (FTIR). Furthermore, comparative evaluation and consumption analysis were carried out to assess removal efficiency and energy consumption of the three methods. The results demonstrated that centrifugal sedimentation was the best way to get the cleanest asphalt binder, while gravitational sedimentation was superior in terms of removal efficiency, and thus it can be used to obtain larger amounts of the “pure” aged asphalt for macrotest. The removal efficiencies of the three methods were affected by the types of asphalt and concentrations of the asphalt-trichloroethylene solutions.