Extruded Tire Crumb-Rubber Recycled Polyethylene Melt Blend as Asphalt Composite Additive for Enhancing the Performance of Binder

Abstract

Concerning environmental problems caused by ever-increasing waste polymers, this paper developed tire crumb rubber (TCR) combined with recycled polyethylene (RPE) extruded melt blend as a composite additive for asphalt modification, aiming to enhance the performance of binder and reutilize extensively waste polymers. The influences of ratio of constituent, extrusion, and devulcanized crumb rubber (CR) on performance of the modified binder were evaluated by rheological methods. Moreover, the phase characteristics and modification mechanism were investigated by optical microscopy and scanning electron microscope (SEM). The results indicated that extrusion for TCR combined with RPE composite additive leads to a decrease in complex modulus and viscosity of the resulting binder. RPE in the composite additive plays a key role in improving the resistance to permanent deformation and reducing viscoplastic behavior. Microscopy showed the coarse RPE phase enveloping CR particles is favorable for improving rutting resistance of binder, whereas smaller particles and an unobvious polymer phase account for the reduced resistance to permanent deformation of binder with devulcanized CR. Extrusion for composite additive improves storage stability of the resulting binder, and devulcanized CR further facilitates stability. The loosened and porous surface of devulcanized CR in SEM sheds a brilliant light on improved storage stability.