Compared with traditional asphalt, emulsified asphalt occurs to be a better low-temperature usability and environmental adaptability, which can reduce environmental pollution and energy consuming during road construction. The low-temperature ductility is a very important indicator to evaluate the environmental adaptability of emulsified asphalt. However, the relevance between microstructure and low-temperature ductility of modified asphalt is still rarely reported. Herein, we reported the first successful unfolding of the microscopic mechanism of ductility attenuation of the modified emulsified asphalt by combining experiments and characterization: Emulsifiers and additives had greater influence on the low-temperature ductility. Anionic and cationic emulsifiers had the similar ductility loss. Adding a non-ionic emulsifier OP-10 could be a solution to improve the ductility. The effect of the temperature change occurred less significant compared to the pH evolution of surfactant solution. The grey relation entropy (GRE) analysis revealed that the emulsifier structure (C/H ratio) would be the most important factor to affect the low-temperature ductility. The macro, micro and nano scales of modified emulsified asphalt were correlated, revealing in-depth that the aggregation and inter-chains interaction of styrene-butadiene-styrene (SBS) were the internal mechanism leading to the ductility loss. The change of glass transition temperature (Tg) was proposed to correlate the microstructural factor with the
ductility. Moreover, the combination of ductility test and bending beam rheometer (BBR) test could be an effective way to evaluate the low-temperature performance of asphalt.@en