Asphalt mixture modification with a plastomeric compound containing recycled plastic: laboratory and field investigation

The use of recycled plastic in asphalt pavements represents a sustainable and economic choice which, if correctly designed, could significantly improve the resistance against the typical distresses of flexible pavements. For this reason, this paper aims at evaluating the mechanical properties of two asphalt mixtures modified with two plastomeric compounds through the dry method, by comparing their results with those obtained for a reference asphalt mixture modified with Styrene–Butadiene–Styrene (SBS) polymers. One of the compounds consisted of plastomeric polymers, whereas the other was made of recycled plastic and graphene. The experimental program included laboratory tests on shear gyratory compacted specimens and cores extracted from a real-scale field trial. The results showed that stiffness, fatigue and rutting resistance of the two polymeric compound modified mixtures were comparable to those of the reference mixture. Finally, a Falling Weight Deflectometer (FWD) campaign, performed in the field after one year of service life of the pavement, showed a reduced structural response of the sections constructed with compound modified mixtures with respect to the reference one because of compaction issues and possible interlayer de-bonding effects.