Influence of RAP Fractionation on the Performance of Binders Extracted from Cold Asphalt Mixes

This study assessed the influence of aged asphalt in reclaimed asphalt pavement (RAP) with asphalt emulsion in cold asphalt mix (CAM) with varying RAP fractionations and contents. The influence was assessed in terms of the physical, chemical, and rheological characteristics of binders extracted from CAM. RAP was fractionated into fine, coarse, and unfractionated types, with 25%, 50%, 75%, and 100% contents. A total of 13 mix combinations were evaluated. Binders were extracted from these mixes produced at optimal emulsion content compacted at 10%±1% air voids using a gyratory compactor. Physical properties like penetration and softening point were measured, while rheological properties were assessed using black space and Cole–Cole diagrams. Chemical analysis included saturates, aromatics, resins, and asphaltenes (SARA) and Fourier transform infrared (FTIR) for carbonyl and sulfoxide indices. The normalized euclidean distance method was employed to rank extracted binders based on their similarity to the control mix. Additionally, four selected mixes were tested with a semicircular bending test to evaluate fracture energy (FE) and cracking potential. Strong correlations exist between physical and chemical properties. Notably, the relationships between chemical parameters and the softening point are more predominant than those with penetration values. Based on the analysis of the extracted binder’s physical and chemical properties, the blending efficiency of coarse fractionation (showing a 36.3% increase in asphaltene content) was found to outperform that of fine fractionation (47.1% increase) and unfractionated RAP (87.8% increase) in cold asphalt mixes. Based on the critical strain energy release rate, the fine fractionated RAP mix was more prone (36.6% reduction from the control mix value) to fatigue cracking, whereas the coarse fractionated outperformed other fractionations.