A study of the influence of the microstructure of one type of bitumen grade on the performance as a binder

• New designed micro-direct tensile test for quantitative determination of adhesive forces.
• Relationship between microstructures of 6 different bitumina and their performance as binder.
• Bitumina with developed microstructures show better adhesion.

Six different bitumina of comparable PEN grade were investigated to gain a relation between the composition and the development of microstructures and their performance as binder material e.g. for road constructions. It was shown, that especially bitumina with explicit microstructures show an intense interaction between the asphaltene nucleated crystals (peri/catana phase) and solid (aggregate and/or filler) surfaces. Consequently, the developed adhesive/cohesive interaction is also stronger in case of such bitumina than in case of bitumina with extended continuous liquid phases (perpetua phase) and such bitumina seem to be well suited for an application as binder material. This was possible by employing a new designed micro-direct tensile test for quantitative determination of adhesive forces including the possibility to study the nature of the failure upon testing.The obtained data were correlated with AFM data from surface structure analysis and verified by other data from literature and other experiments regarding the adhesive interaction of parts of the bitumen with solid surfaces.