Abstract
Zero shear viscosity (ZSV) is a widely accepted rheological parameter. Whereas previous work has mainly focused on unmodified bitumen, this paper discusses how to adopt ZSV for evaluating the rheological properties of polymer modified bitumen (PMB). We found that PMB was unable to reach the steady ZSV condition in a limited time even at a very low frequency level of 0.001rad/s, and the longer the recovery time, the more sufficiently the impact of viscosity could be eliminated. Our results also show that the multiple experimental recovery time test method is more reliable than the common creep test and recovery test for determining the ZSV of PMB. However, the impact of the delayed elastic strain and the delayed elastic recovery strain cannot be eliminated entirely. The ZSV obtained by the Cross model is between 10^2 and 10^3 times higher than those obtained by the other methods, the rest of which lead to similar results. Therefore, not only is accurate measurement critical when adopting ZSV to evaluate PMB, but a scientifically defined division between the viscous and elastic component is also important.
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