Rheological models for non-newtonian viscosity of modified asphalt binders and mastics

Abstract

This paper is aimed at providing a comprehensive experimental work on the viscosity behavior of different modified asphalt binders and mastics, as well as exploring mathematical representations of the results in attempts to predict the viscosity and flow behaviors according to Vinogradov-Malkin and Phillips-Deutsch models. The modified asphalt binders were prepared in the unaged and aged states using styrene-butadienestyrene (SBS), ethylene-vinyl acetate (EVA), and crumb rubber (CR); while the hydrated lime (HL) and fly ash (FA) were selected to produce the binder-filler mastics. To widen the study findings, the additives (polymers, rubber, and fillers) were applied at different possible levels of modification. To prepare the aged bituminous materials, the rolling thin-film oven (RTFO) was utilized for the short-term aging, while the pressure aging vessel (PAV) was further used to induce the possible long-term aging of same materials. Binders and binder-filler mastics were tested using a bob and cup geometry. The viscosity behavior was investigated under various effects of testing conditions including ranges of shear rates and temperatures. It was found that the effect of shear rate dominates and therefore the non-Newtonian shear thinning prevails at low temperatures particularly for binders containing high concentrations of additives. Even the base asphalt binder exhibits shear thinning behavior after a certain limit of shear rate. Based on the studied 38 curves, in general, Vinogradov-Malkin and Phillips-Deutsch models were found in a good agreement with the corresponding measurements especially the latter.