The use of asphalt low shear viscosity to predict permanent deformation performance of asphalt concrete

Abstract

The permanent deformation performance of asphalt concrete is strongly dependent on the rheological properties of the asphalt binder. It has been recognized that the asphalt's low shear viscosity (LSV) characterizes the mixture's rutting resistance. At the same time, the pavement temperature is one of the main factors that significantly affect the mixture performance. In this work the rutting performance of mixtures prepared with the same aggregate gradation and different binders [conventional (C), multigrade (M) and polymer modified (PM) asphalts] were evaluated by using wheel tracking tests (WTT) performed at 50, 60, 70 and 80°C; in parallel, the LSV of asphalts were measured at the same temperatures. The relationship between the asphalt's LSV and rutting, to predict asphalt mixture performance, was discussed and a criterion to consider the effect of LSV is proposed.

Advanced analytical techniques in fatigue and rutting related characterisations of modified bitumen: Literature review

“…Thus, low shear LSV viscosity is sometimes suggested to solve this problem. It was also shown that complex viscosity measured at 0.001 and 0.01 Hz give as a good correlation with mixture rutting performance as those measured at 0.0001 Hz [72].…”

“…The ZSV concept is based on the fact that the purely dissipative viscous component is solely responsible for the non-recoverable deformation [71]. Zero shear viscosity is strongly related to rutting resistance of bituminous materials and many studies showed that ZSV of binders has a strong correlation to rutting performance [72,73]. The ZSV is highly influenced by the higher molecular weight fraction and binder stiffness, and thus, it can reliably predict the rutting resistance of binders under slow-moving load [72].…”

“…The oscillation test has been considered in this paper. Utilising a cyclic oscillatory test in the low-frequency domain has been suggested by many researchers to evaluate ZSV [69,72,74,75]. In this method, a frequency sweep test within the linear viscoelastic regime at a specific high test temperature is used to determine the ZSV [76].…”

“…Also, some modified bitumens experience very high complex viscosity gradients at low frequencies, the ZSV values become unreliable from the rheological point of view [72]. Thus, low shear LSV viscosity is sometimes suggested to solve this problem.…”

“…Even though there have been many comprehensive reviews investigating those characteristics for unmodified bitumens, there have been still limited studies conducted on modified bitumens. For unmodified bitumens, a correlation between the linear viscous component of a bitumen's behaviour and pavement rutting performance, has been well established [27,68,72,73]. However, this correlation has tended to break down with modified bitumens.…”