ZERO SHEAR VISCOSITY OF MODIFIED AND UNMODIFIED BINDERS

Zero shear viscosity (ZSV) has received considerable attention in the past several years as a predictor of the rutting potential of bituminous binders, particurlarly modified binders. In this study, 13 plain and modified binders were tested by a number of different procedures to estimate their ZSV. Procedures included the European project of norm with the creep method, repeated creep, several empirical curve-fitting techniques, simple creep, and procedures based on frequency sweeps obtained with the dynamic shear rheometer. While the methods show some degree of agreement, distinct anomalies were observed caused by either structural changes in the binder or long-term relaxation. Recommendations are given with respect to specification use. For the covering abstract see ITRD E121480.