Observation of polymer modified asphalt microstructure by ESEM

The observation of asphalt binder microstructure with the Environmental Scanning Electron Microscope (ESEM) has yielded promising results. There have been findings that show the microstructure evolving with aging and certain loading applications. The goal of this study was to observe the PMA microstructure using ESEM analysis. Four PMA binders of varying PG grades were observed in ESEM, comparing them to a straight run binder. The binders were compared in terms of the fibril diameter and shape observed visually, along with the fibril structure. The initial 'bee' structures before the appearance of the fibrils were also compared. It was found that the PMA binders had a denser fibril structure, corresponding to their higher PG grades indicating stiffer binders, although this varied with different PMAs. The images were also analyzed by calculating the area and length of the fibrils through an image analysis protocol. This study is a step towards the further understanding of the microstructure of PMAs.