Characterization of the shear-thinning behavior of asphalt binders with consideration of yield stress

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ORIGINAL ARTICLE

Characterization of the shear-thinning behavior of asphalt binders with consideration of yield stress Hanqi Liu . Waleed Zeiada . Ghazi G. Al-Khateeb . Abdallah Shanableh . Mufid Samarai

Received: 21 February 2020 / Accepted: 23 July 2020 Ó RILEM 2020

Abstract This study focused on characterizing the shear-thinning behavior of asphalt binders. The first objective was to identify the existence of yield stress behavior and to employ a rheological model to describe the flow curve of asphalt binders. The second objective was to verify the applicability of the Cox– Merz rule to asphalt binders with consideration of yield stress. A Dynamic Shear Rheometer (DSR) was employed to perform the frequency sweep test and the shear rate sweep test on three types of neat asphalt

H. Liu (&)  M. Samarai Sharjah Research Academy, Sharjah, UAE e-mail: [email protected] M. Samarai e-mail: [email protected] W. Zeiada  G. G. Al-Khateeb  A. Shanableh Department of Civil and Environmental Engineering, University of Sharjah, Sharjah, UAE e-mail: [email protected] G. G. Al-Khateeb e-mail: [email protected]

binders at 50, 60 and 70 °C. The test results of both tests confirmed the yield stress behavior of selected asphalt binders. The asphalt binders were then classified as the shear-thinning liquids with yield stress. As a result, the zero shear viscosity (ZSV), which was utilized as a rutting indicator, was not an indicator of the shear viscosity at zero shear rate but corresponded to the shear viscosity of a Newtonian plateau at low shear rates. A modified Carreau model was employed to characterize the shear-thinning behavior of asphalt binders, which demonstrated the ability to account for the yield stress behavior. The applicability of the Cox– Merz rule was examined by establishing the flow curve and the log–log plot of complex viscosity versus angular frequency in the same graph with respect to each replicate at each temperature. It was demonstrated that the Cox–Merz rule was followed in part of the ZSV region and part of the shear-thinning region but not followed in the yield stress region. Keywords Asphalt binder  Shear thinning  Zero shear viscosity  Yield stress  Modified Carreau model  Cox–Merz rule

A. Shanableh e-mail: [email protected] W. Zeiada Department of Public Works Engineering, College of Engineering, Mansoura University, Mansoura, Egypt

1 Introduction

G. G. Al-Khateeb Jordan University of Science and Technology, Irbid, Jordan

An asphalt binder can exhibit non-Newtonian behavior at a certain temperature range. It has been identified that liquids exhibiting non-Newtonian behavior can be

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divided into three types, which are shear-thinning liquids, shear-thickening liquids and Bingham plastics [1]. As a non-Newtonian liquid, an asphalt binder is of the shear-thinning type [1–3]. The shear-thinning or pseudo-plastic behavior of an asphalt binder is characterized by the dependence of shear viscosity on the she