Recovery and testing of RAP binders from recycled asphalt pavements

Extraction and recovery of asphalt cement from mixtures is a routine task in most asphalt laboratories. Characterization of extracted asphalt binder and aggregate is important for design, quality control, performance prediction and research purposes. Different methods, equipment and solvents for extraction of asphalt binders have significant effects on the properties of the extracted asphalt binder and aggregate. Under NCHRP 9-12, Incorporation of Reclaimed Asphalt Pavement in the Superpave System, a study was conducted to review the variables in extraction and recovery methods. One objective of this study was to evaluate different extraction and recovery methods and determine the best to use for the NCHRP 9-12 study. The second objective was to determine if additional aging of recovered binders is necessary when conducting mix designs in the laboratory. The experimental matrix developed included two different extraction procedures, two recovery methods and three different solvents. Properties of extracted aggregates and asphalt binders from two different Reclaimed Asphalt Pavements (RAP) were studied. The results demonstrate significant variability on properties of extracted asphalt binder with different solvents, extraction and recovery methods. However, the extracted RAP aggregate gradation was not significantly different with different methods and solvents. The aging of the recovered binders demonstrated insignificant changes for the blending of RAP binders.