Composite Asphalt Binders: Effect of Modified RPE on Asphalt

Abstract

Recycled polyethylene (RPE) modified asphalts were prepared and characterized. The RPE was modified with different copolymers before incorporating into the asphalt. A special morphology was found for this system. The RPE particles are highly swollen by asphalt. This morphology is attributed to physical interactions. The presence of copolymers in RPE was found to change the RPE's affinity toward asphalt constituents. Aging of asphalt, oil absorption by polymer particles, and interactions of polymer particles with asphaltenes affect the overall rheological properties of polyethylene modified asphalts. Attempts to approach the rheological behavior of polymer modified asphalt with rheological models for filled polymers were not found to be conclusive. Other specific features of asphalt must be taken into account. These include, for example, changes in the structure that were evidenced by their relaxation time spectra and molecular weight distributions. The polymer modification of asphalt affected the asphalt properties. Well controlled thermomechanical history experienced by the asphalt is needed to differentiate between the chemical changes of the binder due to the mixing process and the beneficial effect of the polymer for high-performance asphalts.