Thermo-rheological behaviour of styrene-butadiene-styrene, hard plastics with or without graphene oxide modified bitumens

With the increase in traffic volume and heavy vehicles, as the changes in climatic conditions, in recent years the design of the road surface has completely changed because it has to guarantee the suitable performance of the pavement. To this end, in recent decades, modifiers have been introduced into the bitumen and, currently, the most performing modifier is SBS (styrene-butadiene-styrene) polymer, but in recent years the investigation on the so-called green additives, obtained from recycled materials or of natural origin is growing. The study intends to investigate, from a rheological point of view, the possibility of using waste hard plastics also in combination with graphene oxide because considered a promising material for new binder generation. For this purpose, the influence that hard plastics, with or without graphene oxide addition, have on the bitumen performance compared to standard SBS-modified bitumens has been studied. The comparison has shown that the plastomeric additive can improve the rheological properties, in the intermediate and high in-service temperature region, while the graphene oxide addition acts on the transitions from viscoelastic to viscous material at high temperature; nevertheless, the aging reduces the effect. In addition, it was found that 4%w/w of hard plastics improve the performance of bitumen and the rheological properties are not affected by the influence of aging.