Improvements on the use of GPC to measure large-size microstructures in aged asphalt binders

Kecheng Zhao, Yuhong Wang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

Gel permeation chromatography (GPC) is commonly used to study the aging and rejuvenation behaviours of asphalt binders, as the sizes of molecules and microstructures in asphalt binders change in such processes. The filtration procedure in preparing GPC specimens, however, may filter out some large-size microstructures in asphalt, making the measured molecular size distribution biased. To investigate this issue, two laboratory-aged asphalt binders and seven recovered ones were studied. Substances filtered from asphalt binders were analysed gravimetrically, followed by examinations using scanning electron microscope (SEM) and scanning transmission electron microscope (STEM). Relationships between binders’ rheological properties and the proportion of large molecular size (LMS) content based on the GPC chromatogram were investigated before and after counting the filtered substances. Results show that microstructures in the recovered asphalt binders differ from those in laboratory-aged ones in both size and morphology. While about 1% of laboratory-aged asphalt binders is obstructed by the GPC filter, 6–10% of recovered ones are blocked. Adding the filtered substances results in better correlations between the rheological properties and the proportion of LMS content. Therefore, in using GPC to analyze aged asphalt binders, it is recommended to count the filtered substances as part of LMS content.

Original languageEnglish
JournalInternational Journal of Pavement Engineering
DOIs
Publication statusAccepted/In press - 2020

Keywords

  • asphalt aging
  • filtration
  • GPC
  • large molecular size
  • microstructures

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Mechanics of Materials

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