Modeling of the viscoelastic behavior of polymer-modified asphalts

An analysis and modelling of the linear viscoelastic behavior of maltenes (M) blended with styrene-butadiene-styrene block copolymer (SBS) are presented in this study. M were mixed with different amounts of SBS (Elastomer, E) (0.25 to 80 wt.%) to investigate the effect of polymer concentration on linear viscoelastic response of the blends; storage and loss moduli were obtained from small amplitude oscillatory shear tests (SAOS). Time-temperature superposition master curves were analyzed by a Maxwell multimodal model with up to nine relaxation times. Han, Cole-Cole and Van Gurp-Palmen diagrams were prepared from the rheological data. Two different responses were observed: At low E contents, a dispersed system rheological response was observed and verified by microscopy with elastomer as the dispersed phase and maltenes as the matrix, while at high E content the response was that of a co-continuous system. Mixtures with E > 2 wt % exhibited change in their thermomechanical properties with a phase inversion at E > 50 wt. %. Furthermore, at low E concentration resins stabilize the dispersed phase by diminishing the magnitude of the viscoelastic moduli, conversely, at high E concentration a swelled polymer-rich phase creates a network that significantly influences of the viscoelastic properties.