Creep characteristics of asphalt modified by radial styrene–butadiene–styrene copolymer

The aim of this work was the comparison of estimated zero-shear viscosity (ZSV) from both parts of the creep and recovery curve with directly measured ZSV, for asphalt modified with different amounts of radial styrene–butadiene–styrene (SBS) copolymer. Various time durations of creep and recovery were examined. The impact of waiting time between tests on creep compliance and the zero-shear viscosity was investigated; and, the influence of the stresses (between 25 Pa and 5 kPa) was also studied. Both the steady state and viscous compliances of the studied materials were calculated and the resulting viscosities were compared with the ones measured with the ARES rheometer. The structure time dependency of the polymer-modified asphalt, observed in interrupted shear flow, is also briefly discussed.It has been shown that the studied polymer-modified asphalt has a time-dependent microstructure. This effect is manifested clearly at higher deformations or stress levels. At these higher distress modes, the polymer-modified asphalt exhibited behaviour that is outside of the linear viscoelastic domain. Thus, the criteria developed for the linear viscoelastic behaviour should not be applied to the tested asphalt.