Correlation Analysis of Chemical Components and Rheological Properties of Asphalt After Aging and Rejuvenation

To study the correlation between the chemical composition and rheological properties of neat asphalt after aging and rejuvenation, the neat asphalt with different aging time was prepared, and its rheological properties were tested by dynamic shear rheology (DSR) and bending beam rheology (BBR). The functional groups were tested by the Fourier transform infrared (FTIR). Based on the gray entropy correlation analysis (GECA), the correlation of test parameters was analyzed linearly. The results show that with the aging of asphalt, the complex modulus (${\mathrm{G}}^{*}$), phase angle ($\delta$), and creep rate ($m$) decrease, while the creep stiffness ($S$), carbonyl index (CI), and sulfoxide index (SI) increase. After the addition of regenerating agent, the rheological performance indexes and the content changes of characteristic functional groups of recycled asphalt are opposite to those of aging asphalt. The gray entropy correlation degrees among the SI/CI, $\delta$, and ${\mathrm{G}}^{*}$, and among the rutting factor (${\mathrm{G}}^{*}/\sin \delta$), creep stiffness $S$ ($-12°\mathrm{C}$, $-18°\mathrm{C}$, and $-24°\mathrm{C}$) and creep rate $m$ ($-12°\mathrm{C}$, $-18°\mathrm{C}$, and $-24°\mathrm{C}$) are more than 0.96; the rheological parameters $\delta$, ${\mathrm{G}}^{*}$, ${\mathrm{G}}^{*}/\sin \delta$, and $S$ ($-18°\mathrm{C}$ and $-24°\mathrm{C}$) of asphalt have a unary linear relationship with the SI/CI, and its rheological parameters $\delta$, ${\mathrm{G}}^{*}$, ${\mathrm{G}}^{*}/\sin \delta$, $S$ ($-18°\mathrm{C}$ and $-24°\mathrm{C}$), and $m$ ($-24°\mathrm{C}$) have a binary linear relationship with the composite index (AI) (SI+CI). These findings are of great significance to understanding the evolution law of rheological properties of neat asphalt after aging and rejuvenation.