Assessment of Aging Impact on Wax Crystallization in Selected Asphalt Binders

Wenqi Wang; Ali Rahman; Haibo Ding; Yanjun Qiu

doi:10.3390/ma15228248

Assessment of Aging Impact on Wax Crystallization in Selected Asphalt Binders

Materials (Basel). 2022 Nov 21;15(22):8248. doi: 10.3390/ma15228248.

Authors

Wenqi Wang¹, Ali Rahman^{2

3}, Haibo Ding^{2

3}, Yanjun Qiu^{2

3}

Affiliations

¹ School of Architecture and Civil Engineering, Xihua University, Chengdu 610039, China.
² School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China.
³ Highway Engineering Key Laboratory of Sichuan Province, Southwest Jiaotong University, Chengdu 610031, China.

Abstract

For a better understanding of the changing trend in crystalline components of asphalt binders, asphalt binders originating from the SHRP Materials Reference Library with different oxidation degrees (unaged, 20 h PAV, and 60 h PAV) were prepared. The native asphalt binders and their oxidized residues were characterized by liquid-state nuclear magnetic resonance (NMR) spectroscopy and high-temperature gas chromatography (HTGC). The results showed that, compared with other carbon types, the content of internal methylene carbons of long paraffinic chains between different SHRP binders was quite different. The NMR average length of a long paraffinic internal methylene chain showed a good correlation with the wax content obtained at -20 °C using the methyl ethyl ketone (MEK) precipitation method and also the recently developed variable-temperature Fourier-transform infrared spectroscopy (VT-FTIR) method. In most cases, the average length of straight internal methylene carbons of a long paraffinic chain terminated by a methyl group increased with the oxidation of the asphalt binder. However, the difference caused by oxidation was significantly smaller than the difference caused by the source of the asphalt binder. In general, oxidation will make the n-alkanes distributed in asphalt binder fall within a narrower range. The carbon number of n-alkanes in the asphalt binder generally grew with oxidation.

Keywords: aging; asphalt binder; gas chromatography; nuclear magnetic resonance; oxidation; wax.

Grants and funding

This research was funded by 1. Talent Introduction Project of Xihua University (School Key Project) (Z202111); 2. Scientific research project of Sichuan Provincial Department of Education (16ZB0164); 3. Open Research Fund of Sichuan Provincial Key Laboratory of Road Engineering (15206569); 4. Open project of Sichuan Key Laboratory of Green Building and Energy Saving (szjj2015-074).