Relation of chemical composition to asphalt microstructure - Details and properties of micro-structures in bitumen as seen by thermal and friction force microscopy and by scanning near-filed optical microscopy

Bitumen and bituminous binders are a mixture of a wide variety of molecules with different size and nature; a-polar as well as polar, aromatic as well as aliphatic, chain-like as well as two-dimensional in nature. However, most of the bitumina display at ambient temperatures a spontaneous formation of micro-phases displaying different mechanical properties such as stiffness or adhesive behaviour. The actual chemical composition of the individual phases is still a matter/subject of discussion. The application of different scanning probe microscopy modes such as FFM, SThM and SNOM enabled the investigation of the relationships between asphalt microstructure and material characteristics such as friction coefficient, thermal conductivity and chemical composition and polarity. It was possible to collect data providing more and detailed information's on a nano-scale and in detail with respect to the different micro-phases present in bituminous binders. All data collected fit into the present picture of structuring of bitumen and the characteristics of the present phases