Revealing the dependance of mechanical properties of asphalt binder on graphene size via multi-scale methods

Abstract

Elucidating the specific interaction between graphene with various structures and asphalt is essential to promote the wide adoption of graphene modified asphalt for high-performance pavement engineering. Herein, the enhancement of modified asphalts with nano-sized graphene (NG) and micro-sized graphene (MG) were systematically investigated by using dynamic shear rheometer (DSR), atomic force microscopy (AFM) and molecular dynamics (MD) simulation at multi-scale levels. The results demonstrate that MG can significantly enhance the deformation resistance and low-temperature crack resistance of modified asphalt, compare with NG, and AFM confirm that MG can obviously affect the rearrangement of four components in asphalt to form a micellar structure with higher modulus and lower energy dissipation. MD simulation further verifies that the higher mechanical strength of large-sized graphene modified asphalt is attributed to the reduced slide movement of cavitation structures in asphalt, since the larger graphene not only has stronger π-π interaction with asphaltene and resin, but also induces one more specific interaction of hydrogen bonds (O-H···S) between these polar components. The coupling interaction facilitates the formation of more compact micelles, resulting in the improved mechanical properties of asphalt. The elucidation of graphene size effect on asphalt provides encouragement for understanding the enhancement of graphene modified asphalt.

Keywords

• Graphene
• Asphalt binder
• Mechanical properties
• Size effect