Zero-Shear Viscosity of Bituminous Binder and Its Relation to Bituminous Mixture's Rutting Resistance

Abstract

When testing viscosity of polymer-bitumen systems a question arises about interpretation of results as those systems behave as non-Newtonian liquids. A simple equation modeling non-Newtonian behavior of polymer-bitumens was proposed (which is a simplified version of the CROSS model). The equation used enables the calculation of zero-shear viscosity η₀ from viscosity measurements conducted under various shear conditions, that is, with rotational viscometer at different shear rates (stresses). Test results are presented of several polymer-modified bituminous binders before and after Thin film oven test aging and discussion of non-Newtonian behavior. The wheel tracking test (Laboratoric Central des Ponts et Chaussées) was conducted for asphalt concrete with several bituminous binders, either plain bitumens or polymer modified. To estimate bituminous mixture's rutting resistance, a new relationship has been proposed to calculate N₁₀ (wheel passes number to rut depth 10 mm). Close correlation was found between N₁₀ and zero-shear (or absolute) viscosity of binders at 60°C, both conventional and polymer modified.