Quantification of activated aged binders in recycled asphalt mixture: a nanoscale indicator approach without binder extraction

Various methods exist to quantify the degree of blending (DOB) in recycled asphalt mixtures, but most rely on chemical extraction that may alter the true blending state. A recent atomic force microscopy (AFM)-based method enables direct, non-destructive characterization of nanoscale properties without binder extraction. This study validates the feasibility of using nanoscale indicators to represent DOB. Nanoscale morphological, mechanical, and chemical properties of reclaimed binder were measured and correlated with macroscopic properties. The Pearson correlation and entropy weight method identified the nanoscale Derjaguin-Muller-Toropov (DMT) modulus as the most suitable indicator. An estimation model linking nanoscale properties to mobilised aged binder content was developed and verified. Based on these findings, a solvent-free approach for quantitative DOB evaluation is proposed, offering a reference for non-destructive assessment and mixture design optimization.