On the investigation of the bulk microstructure of bitumen - Introducing two new techniques

Bitumen, the residue of oil distillation and applied e. g. as binder in asphalt pavements displays a rich microstructure at the bitumen surface-to-air surface with several clearly distinguishable phases. However, uncertainty still remains whether this micro-structure is just present at free surfaces or a similar structure exists in the bulk of the material. Two new experimental techniques in bitumen research (i) one based on Atomic Force Microscopy (AFM) on a freeze-fracture surface and (ii) one technique employing a Scanning Acoustic Microscope (SAM) offer the required spatial resolution and show the presence of two phases in the bulk showing similarities with the known surface structures in bitumen. (C) 2013 Elsevier Ltd. All rights reserved.