Interfacial Evolution and Long‐Term Aging Behavior of Waste Polyethylene‐Modified Bitumen Compatibilized With Ethylene‐Vinyl Acetate

ABSTRACT

The aim of this work is to determine whether ethylene‐vinyl acetate (EVA) can provide durable compatibilization between waste polyethylene (WPE) and bitumen under prolonged oxidative aging, given that poor compatibility typically limits the use of WPE in pavement applications. To investigate this, blends with 6 wt% total polymer and varying WPE/EVA ratios were subjected to pressure aging vessel treatment for up to 60 h. The optimally compatibilized B‐3/3 formulation maintained a diffuse, crack‐free interphase even after extended aging, as revealed by multi‐scale microscopy, in stark contrast to the sharp, debonded interfaces observed in the uncompatibilized system. Chemical analysis showed that this stable interface effectively suppressed oxidative degradation, achieving a 35% reduction in the carbonyl index relative to neat bitumen, while rheological testing confirmed superior fatigue life (245,000 cycles) and storage stability (a softening point difference of only 1.4°C after 60 h). These results support an anchor–scaffold mechanism, where EVA provides molecular bridges while WPE retains degraded fragments, ensuring durable compatibilization. The 3/3 WPE/EVA ratio is therefore identified as offering an optimal balance between initial compatibility and long‐term aging resistance.