Time–temperature superposition in rheology and ductile failure of asphalt binders

Abstract

This paper documents and discusses an investigation into the time–temperature superposition principle as it relates to ductile failure in asphalt. Seven binders of approximately the same low and intermediate temperature and varying high temperature Superpave® grades were tested in a dynamic shear rheometer (DSR) and double-edge-notched tension test to determine their rheological and failure energy master curves. Master curves typically permit the prediction of rheological properties at very long or short timescales from measurements at higher or lower test temperatures over more accessible testing timescales. It has been suggested in the Strategic Highway Research Program final report A-369 that rheological shift factors obtained from a DSR experiment can be used to predict failure master curves from experimentally accessible data at various temperatures. The findings of this study suggest that this substitution is not generally accurate. For straight asphalt binders the difference can be relatively small but for more highly modified materials serious errors would be introduced.