Characterizing SBS modified asphalt with sulfur using multiple stress creep recovery test

The effect of cross-linking agent and SBS content on SBS modified asphalt were investigated using multiple stress creep recovery (MSCR) test. Nonlinear viscoelastic characterization of MSCR curve was also performed to derive nonlinear viscoelastic parameters. Cross-linking agent can prominently improve high temperature properties of SBS modified asphalt, especially at lower polymer content. The effect of increasing SBS content is more prominent for binders at lower SBS content. MSCR test failed to distinguish 5.0% and 5.5% SBS modified asphalt in this limited study. All binders modified from 3.0% to 5.5% SBS with sulfur have sufficient delayed elastic response according to AASHTO TP 70. When cross-linking agent was not used, only high dosage SBS modified binders are considered to be modified with an acceptable elastomeric polymer in this study. In addition, there is strong linear relationship between percent recovery and Jnr and such relationship is not dependent on stress level, but is concerned with test temperature. The nonlinear parameter G2 derived from MSCR curve can be used to identify the existence of cross-linking agent and characterize the elastic response of SBS modified binder. The parameter PS% shows potentiality in evaluating modified binder's ability to resist permanent deformation. However, PS% used in this study should be further investigated to confirm the applicability for highly modified asphalt.