The aim of this article is the comparison of flow properties of base and polymer-modified asphalts in different experimental modes. Various concentrations of polymers were added to base asphalt. Effect of the modification was observed and peculiar behaviour (noticed especially in steady state measurements) was modeled. When polymer-modified asphalts are studied in small amplitude oscillations, the obtained dynamic material functions are not very different qualitatively from those of

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... asphalts. The situation is changed when the same materials are studied in the strong steady shear regime (with a broad range of shear rates). In the blends of soft (conventional) asphalt with styrene-butadiene-styrene (SBS) and ethylene-vinyl-acetate (EVA) copolymers, the shear viscosity function exhibits a typical non-Newtonian behaviour at some temperatures. Then, at other temperatures (depending on the polymer and its concentration), the viscosity function has a double-step shear-thinning behaviour and, in some cases, even a small shear-thickening region can be observed. This unusual behaviour is caused by rearrangement of a polydomain structure and detachment of flexible chains in polymer-modified asphalt. The resulting network is responsible for the nonlinear behaviour of polymer-modified asphalts. It is shown that the generalized rubber-like liquid model can describe this nonlinear behaviour of polymer-modified asphalts well.