The Effect of Aging on the Molecular Distribution of Crumb Rubber Modified Asphalt Based on the Gel Permeation Chromatography Test

Abstract

Asphalt aging is one of the main causes of asphalt pavement cracking, loosening and other issues. On a macro level, the asphalt hardens and becomes more brittle, while on a micro level, the chemical composition and molecular weight distribution change. This is a very complicated physicochemical process. Gel permeation chromatography (GPC) is a powerful technical tool for understanding the mechanism of asphalt aging and expressing the asphalt aging process. GPC can be used to measure the distribution and content of each component in the asphalt aging process. The mechanism of action of crumb rubber modified asphalt has not been fully elucidated due to its complex composition. This study investigated the molecular weight of crumb rubber modified asphalt before and after aging, and filtered asphalt based on gel permeation chromatography. The results indicated that crumb rubber itself experiences severe degradation following PAV aging and that a significant number of macromolecular materials are incorporated into the asphalt phase, causing changes in key parameters. The average molecular weight (Mw) and dispersion (D) of crumb rubber modified asphalt are directly related. At the same time, the Mw of crumb rubber modified asphalt has a positive correlation with LMS content, while SMS content has a negative correlation with Mw. The increase in crumb rubber content has a positive impact on the material interaction, and the molecular weight distribution of crumb rubber modified asphalt is affected by the reaction degree of the crumb rubber in asphalt. The complex physical and chemical reaction of crumb rubber in asphalt has a direct impact on the external macro rheological properties of asphalt.