Evaluation of Rheological and Moisture Damage Properties of Crumb Rubber-Modified Asphalt Binder

This study investigates the influence of crumb rubber (CR) particles on the rheological and moisture damage properties of asphalt binder. A control neat asphalt binder (AC-10) and 30# CR are chosen for the preparation of CR-modified asphalt (CRMA) binder. A total of four different CR dosages (0, 5,10, and 15 % by weight of binder) was selected for the preparation of four combinations of CRMA binder. The rheological performance of CRMA binders was investigated based on Superpave rutting parameter, multiple stress creep recovery, Superpave fatigue parameter, and linear amplitude sweep (LAS) test using dynamic shear rheometer. Moisture damage response of CRMA binder was evaluated using surface free energy and bitumen bond strength test. CR particles significantly enhanced rut resistance of neat asphalt binder at high temperatures with improved stiffness properties and elastic response. Superpave fatigue factor and LAS test results showed that CRMA binder containing a CR dosage up to 10 % has improved fatigue life and is less susceptible to strain amplitude at an intermediate temperature. CRMA binder with 5 % CR predominantly shows better resistance to moisture damage with good interfacial energy and compatibility ratio at the aggregate interface. However, BBS test results imply that the contribution of high dosages of CR (5 to 15 %) is significant in improving the bond strength and moisture damage resistance of CRMA binder.