Different Forms of Asphaltene Microstructures Discovered in Transmission Electron Microscopy

Recent advances in characterizing the “bee” structures and asphaltene particles in asphalt binders

“…Firstly, the samples have to be very thin to enable electrons to pass, usually in the range of hundreds of nanometers or even less. In early attempts, the authors used solvent casting to create thin films for the observation of asphalt binders and asphaltenes in STEM [17]. In later experiments, the authors developed a new method to create thin films without solvent casting.…”

“…Thirdly, it is difficult to create a threedimensional view of an object based on TEM images. In previous studies by the authors [17], STEM has been successfully used in characterizing asphaltene particles in asphalt binders. This paper will only briefly introduce some major findings from STEM studies.…”

“…For example, more noticeable microstructure agglomeration can be found in some regions of binder AAM-1. Based on the analysis of asphalt binders from different sources, one existing paper attributes those microstructures to asphaltenes [17].…”

“…The separately asphaltene microstructures have been examined and discussed in detail in an existing paper [17]. For the interest of completeness, one of such microstructures in a larger size and the details of a needle-shaped microstructure are shown in Fig.…”

“…In addition, it is still arguable whether the surface features are exclusive to the surface of the asphalt binder specimens or also present inside the specimens. In addition to AFM, other techniques have also been used to investigate microstructures in asphalt binders, including transmission electron microscopy (TEM) and scanning electron microscopy (SEM) [17].…”