Study on the construction of storage stability master curve and evaluation methods of high content SBS modified asphalt under thermal time coupling effect

Due to the significant differences in molecular weight and density between styrene-butadiene-styrene (SBS) and asphalt, SBS modified asphalt trends to phase segregation, particularly at high SBS content levels (≥5 %). Rapid and effective evaluation of the thermal storage stability of high content SBS modified asphalt (HSMA) has gained a lot of attention. This study established a storage stability master curve model for HSMA based on extend segregation tests, using softening point difference (D SP ) and segregation rate (Rs) as evaluation parameters. The Pearson correlation coefficient (r), Euclidean distance (d E ), and stability index (SI) were employed to investigate the phase separation behavior of HSMA under various thermal conditions. Fluorescence microscopy (FM), combined with contour fitting and logistic regression analysis, was used to characterize the microstructural evolution of HSMA. Finally, a random forest algorithm was applied to perform sensitivity analysis on several commonly used storage stability indicators for modified asphalt. The results showed that the construction of a storage stability master curve under thermal time coupling enables rapid and effective evaluation and prediction of the segregation behavior of HSMA under various thermal storage conditions. Compared with other evaluation indicators, the d E value derived from Cole-Cole plots is the most sensitive in HSMA storage stability changes, followed by SI and r. In contrast, the CV and SE values obtained from FM images showed relatively lower sensitivity and could be considered as auxiliary evaluation indicators. • The thermal stability of modified asphalt can be characterized through the construction of storage stability master curve. • D SP and Rs can be used to construct storage stability master curves of HSMA. • The d E value enables quantitative characterization of Cole-Cole plots. • The SI value obtained from the MSCR test can effectively evaluate the phase segregation degree of HSMA.