Reclaimed Asphalt Pavement Binder Extraction and Recovery Evaluation and Their Effects on the Recycling Agent Assessment

Abstract

The use of reclaimed asphalt pavement (RAP) has proved to be an advantageous alternative for the restoration and construction of new roads, with regard to the economical and environmental performance of the recycled material. However, one of the concerns about the use of RAP in the production of new asphalt mixtures is related to its inherent variability, manifested mainly in the asphalt binder. Some procedures to recover the aged binder are commonly used, such as extraction with solvents and recovery applying distillation techniques. These methods might change the intrinsic properties of the asphalt binder (e.g., rheological and chemical characteristics), which may lead to flaws in the dose of the recycling agent. The present study evaluated the variability of the techniques of asphalt binder extraction-recovery from a RAP source, and its effects on the final assessment of binder blend between RAP binder and a softer binder for recycled hot mix asphalt. The results show that automated extraction provided statistically satisfactory values for determination of the RAP binder content. The recovery method conditions, however, were not efficient with regard to solvent removal for 40% of the analyzed RAP samples. Pearson’s coefficients indicated a weak correlation between RAP binder aging indices and its rheological behavior, probably because of the presence of solvent. Tetrachlorethylene (TCE) spectrum band at wavelengths of 903 to 915 cm⁻¹ tends to affect binder stiffness more than wavelengths of 771 to 783 cm⁻¹, underestimating high temperature continuous performance grade ( $T_c$ ) and consequently the binder blend results.