Fatigue Performance of Rubberized Stone Matrix Asphalt by a Simplified Viscoelastic Continuum Damage Model

The study investigated the fatigue performance of rubberized stone matrix asphalt (SMA) in the dry process and compared its
fatigue characterization with SMAs with other typical binders. Five SMA mixtures were used with the following asphalt binders: (1) virgin
asphalt of PG 67-22, (2) crumb rubber modifier (CRM) modified in wet process, (3) CRM modified in dry process, (4) terminal-blend binder,
and (5) styrene-butadiene-styrene (SBS) modified binder. Dynamic modulus and direct-tension fatigue tests were performed using the asphalt
mixture performance tester (AMPT) system. In addition, improved linear amplitude sweep (LAS) tests were performed on the binders by a
dynamic shear rheometer (DSR). The fatigue test data were analyzed by the simplified viscoelastic continuum damage (S-VECD) theory. The
results showed that (1) dynamic modulus of the rubberized SMA in the dry process was similar to that of the wet process and higher than that
of SMAwith virgin asphalt, although a little lower than those of SMAs with terminal-blend binder or SBS binder at high temperatures; (2) the
damage resistance and fatigue life of the rubberized SMA in the dry process are higher than those of SMAwith virgin asphalt and similar or
slightly higher than with the wet process, but lower than SMAs with terminal-blend binder or SBS binder; and (3) the virgin binder had lower
damage resistance and fatigue life, followed by the CRM binder in the wet process, the terminal-blend binder and SBS binder had higher
damage resistance and fatigue life. This is consistent with the mixture results for the direct-tension fatigue tests.