Ageing characteristics of polyethylene-modified asphalt binders blended with different compatibilisers

In this study, virgin low-density polyethylene (LDPE) and recycled polyethylene (RPE) were blended with an asphalt binder in combination with compatibilizers such as styrene-butadiene-styrene (SBS), Elvaloy, sulfur, and polyphosphoric acid (PPA): LDPE, LDPE + SBS + Sulfur, LDPE + Elvaloy, LDPE + Elvaloy + PPA, LDPE + sulfur, RPE, RPE + sulfur, and RPE + PPA. This study aimed to investigate (1) the distribution of PE in asphalt binder, (2) chemical changes in the binder due to the addition of compatibilizers, and (3) the ageing characteristics and their effects on the rheological and performance properties. Micrographs revealed that the LDPE dispersity improved with the addition of Elvaloy. The PE blends with sulfur met the target performance grade of PG76V-10. The PE blends with sulfur exhibited the highest fatigue life at low strain levels and degraded rapidly with an increase in strain level. The LDPE blends with Elvaloy experienced the least degradation in fatigue life with an increased strain level; this low ageing susceptibility was due to the lowest carbonyl (Ic=o) and sulfoxide (Is=o) index values.