Relation between polymer architecture and nonlinear viscoelastic behavior of modified asphalts

The use of polymer modified asphalts for waterproofing and in road pavement has been continually increasing worldwide, because a relatively small quantity of added polymer can significantly enhance performance and durability. The knowledge of the morphological structure of such materials is still incomplete and controversial, mainly because of the compositional complexity. In practice, rheology is one of the most useful tools for the study of polymer modified asphalt. Particularly, nonlinear rheology may give unique information that helps to interpret how the polymer organizes when it is blended with asphalt. In this paper, besides a brief description of linear rheological properties and modeling, particular attention is paid to the most recent studies on the structure and to material functions, such as shear viscosity and relaxation modulus in the nonlinear viscoelastic region. The correlation of nonlinear behavior with polymer characteristics and with the architecture established when polymers are blended with asphalts is then described.