Rheology and storage stability of modified binders with waste polymers composites

Abstract

The purpose of this study was to characterise the potential effectiveness of utilising three melt-compounding combinations of recycled polyethylene terephthalate (PET) and crumb rubber to improve rutting and fatigue damage resistance of two base asphalt binders. The rheological and stability properties of two unmodified and six modified asphalts were evaluated using rotational viscosity, dynamic shear rheometer, accelerated damage tests (multiple stress creep and recovery and linear amplitude sweep tests) and storage stability tests. Findings of the viscosity test proved an increase in binder stiffness at construction temperature by application of these combined polymers. The suggested polymers improved binder elasticity and recovery properties implying greater resistance against thermal rutting damage and the enhancement increases by incorporating higher PET; however, the PET increase would create a stress sensitive binder at unexpected loading and temperature conditions. Furthermore, the modified binders experienced higher resistance to fatigue cracking at intermediate temperatures compared with the neat asphalt binders while not following the definite increasing trend with changing crumb rubber/PET ratio and the most improvement occurring for modified binders with 70/30 crumb rubber/PET ratio. Regarding storage stability, the high percentage of modifiers increases polymer separation potential at high temperatures of asphalt mixture construction, and there is no consistent trend between increasing PET and hot storage stability according to two methodologies.