Improving Asphalt Binder's Elasticity through Controlling the Interaction Parameters between CRM and Asphalt Binder

Crumb rubber modifier (CRM) is considered one of the most commonly used modifiers that enhances the rheological properties of asphalt binders. Optimizing the interaction process between CRM and asphalt binder to enhance the asphalt binder's elasticity without additional additives is the main purpose of the article. Rheological properties were measured in this article for neat asphalt and crumb rubber modified asphalt (CRMA) binders. Two sets of interactions were selected. In the first interaction set, one interaction temperature (190 degrees C), one interaction speed (3,000 rpm), and different interaction times (0.5, 1, 2, 4, and 8 h) were used. The used CRM percentage was 10 % by weight of the neat asphalt binder. Two sources of asphalt binder, one source and different percentages of CRM, one interaction temperature (190 degrees C), one interaction speed (3,000 rpm), and different interaction times were selected for the second interaction set. This set was designated to confirm the rheological properties obtained for the first set. Thermogravimetric analysis (TGA) was performed on CRM particles before and after their interaction with asphalt binder after different interaction times. The CRMA binders that interacted for the entire 8-h interaction times had significantly enhanced properties, especially the elasticity, as compared to the neat asphalt binder. The 8-h interaction time showed the highest CRM dissolution percentage by dissolution and TGA testing. At this interaction time, more CRM components were released into the asphalt binder liquid phase, which was detected by observing Fourier-transform infrared peaks at 966 cm-1 for polypropylene and 699 cm-1 for polystyrene.