Investigating the relationship between chemical composition and mechanical properties of asphalt binders using atomic force microscopy (AFM)

• Published in: Construction & building materials Vol. 343; p. 128001
• Main Authors: Zhang, Enhao, Shan, Liyan, Qi, Xiaofei, Wang, Xin, Fan, Youjie
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 08-08-2022
• Subjects: Asphalt; Mechanical property; Microstructure; SARA (saturate, aromatic, resin, and asphaltene); SARA (saturate, aromatic, resin, and asphaltene); Asphalt; Microstructure; Mechanical property
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2022.128001

•New asphalts with different SARA content are designed, and the composition-structure-mechanics relationship is analyzed.•Bee structures are composed of asphaltene and resin.•Micro-mechanical properties of asphalt binders are affected by two fractions together rather than one single fraction.•The effect of SARA on rheological properties at both macro- and micro-scales of asphalt binder show the same trend.
As a complex mixture, the composition-structure-mechanics relationship of asphalt binders is not well-understood. Thus, it is essential to understand the relationship between chemical composition and mechanical properties. Saturate, aromatic, resin and asphaltene (SARA) fractions are crucial chemical components of asphalt binders. At present, the main challenge faced by many researchers is the relationship between the SARA fractions and the microstructure, and how the SARA fractions affect the micro-mechanical properties of asphalt binders. In this paper, the composition-structure-mechanics relationship were studied using atomic force microscopy. The asphalt samples were divided into two groups. Firstly, different kinds of asphalt binders with different SARA content were compared. Then, new asphalt binders were derived and their properties were analyzed. Results show that bee structure appears on the surface of asphalt binders with higher asphaltene and resin contents, it means that the formation of bee structures is related to the aggregate of asphaltene and resin. Moreover, the micro-mechanical properties of the asphalt binders are affected by two fractions rather than a single fraction. The adhesion force increases with the increase in saturate and aromatic contents, and decreases with the increase in asphaltene and resin contents. The Derjaguin–Müller–Toporov (DMT) modulus, storage and loss modulus increase with the increase in asphaltene and resin contents, and decreases with the increase in saturate and aromatic contents. Furthermore, SARA fractions have the same effect on both the micro- and macro-rheological properties of asphalt binders. These findings will help to improve the understanding of the composition-structure-mechanics relationship of asphalt binders, which in turn will aid in optimizing their performance.