Structure-activity Relationship Between Molecular Structure Change and Its Rheological Properties and Chemical Composition of UV Aged Asphalt

In order to study the molecular weight and molecular structure changes of asphalt under ultraviolet(UV)aging and their effects on rheological properties and chemical compositions,gel permeation chromatography and nuclear magnetic resonance tests were carried out on four kinds of asphalt commonly used in engineering. The changes of molecular weight index,such as molecular weight,molecular relative mass distribution,and molecular structure,and the molecular structure index including hydrogen spectrum,carbon spectrum,hydrogen atom content and molecular structure parameters were studied before and after ultraviolet aging. On the basis of rheological properties tests,the molecular composition of asphalt rheological properties was analyzed by correlation analysis method,and the change mechanism of asphalt rheological properties during ultraviolet aging was explained from the molecular level. The results show that ultraviolet aging causes the agglomeration of molecules in asphalt, agglomerate,and small molecules decrease to into large molecules,and the molecular weight distribution boundary becomes narrower. From the changes of hydrogen atoms and molecular structure parameters,it can be seen that the alkyl substituents on the aromatic ring in the asphalt increase after ultraviolet aging,which leads to the increase of the volume of the aromatic ring and the increase of the internal molecular stability of the asphalt,and the decrease of the rheological property of the asphalt at the macro level. The macro and micro evaluation indexes of asphalt were determined by the rheological properties and chemical composition of asphalt. From correlation analysis,it was found that the rheological properties of asphalt were most affected by the condensation degree parameter of aromatic ring,hydrogen substitution rate around aromatic ring, number average molecular weight,aromatic carbon rate,alkyl and naphthenic branched chains,and aromatic structure. © 2025 Cailiao Daobaoshe/ Materials Review. All rights reserved.