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Microstructure of Neat and SBS Modified Asphalt Binder by Small-Angle Neutron Scattering



Liyan Shan, Ru Xie, Norman J. Wagner, Hongsen He, Yun Liu


The microstructure of asphalt binders has been believed to have a significant impact on the performance of binders used in roadway constructions. However, there are only limited studies of their nanoscale to microscale structures. Here, small angle neutron scattering (SANS) is used to study the nanoscale structure of neat asphalt binder, block copolymers (styrene-butadiene-styrene) (SBS) and SBS modified asphalt binder. The SANS pattern for asphalt binder demonstrates that it exhibits a colloidal structure comprised of asphaltenes surrounded by resins dispersed in saturates and aromatics. Fractal-core-shell model fits to these patterns indicate that the asphaltene core size decreases with increasing temperature. Both SANS and rheology confirm that SBS modified asphalt has a thermo-reversible phase transition around 110°C, where the SBS micelles swell and lose scattering contrast above this temperature. The thermo-reversibility of this phenomenon indicates that the SBS modified mechanism is mostly a physical modification of the nanoscale structure as proposed in the colloidal model of asphalt. Modeling of the SANS patterns shows that neat SBS and SBS dispersed in asphalt binder have a lamellar structure surrounded by a shell. These results are useful for understanding the relationship between the nanoscale structure of asphalt binder and pavement performance, as well as potentially developing new types of modified asphalt binders.


small angle neutron scattering, asphalt


Shan, L. , Xie, R. , Wagner, N. , He, H. and Liu, Y. (2019), Microstructure of Neat and SBS Modified Asphalt Binder by Small-Angle Neutron Scattering, Fuel, [online], (Accessed March 5, 2024)
Created September 30, 2019, Updated October 12, 2021