Improving the rheological properties of crumb rubber modified binder using hydrogen peroxide

To overcome the problems of segregation between the rubber particles and the asphalt binder in the crumb rubber modified asphalts (CRMAs) different solutions were tested, including the establishment of chemical bonds between the different components of CRMA and the asphalt materials. In this research, a chemical method was employed to treat variously manufactured (ambient and cryogenic grinded) crumb rubbers' surfaces in order to graft functional groups and improve bitumen-rubber compatibility and reduce segregation. In general, 400g of crumb rubber was heated to 80 +/- 2 degrees C and was continuously stirred with 100.1ml of hydrogen peroxide and 90.1ml of FeSO4 for 30min. Then the activated crumb rubber was processed into asphalt for 60min at 177 +/- 2 degrees C. Hydrogen peroxide treatment significantly reduced phase separation; it produced even more stable suspension when FeSO4 catalyst was employed. The surface differences of cryogenic and ambient grinded rubbers resulted differences in the flow properties, especially in shear elasticity.