Performance assessment of waste-plastic modified asphalt mixtures for road pavements =

In line with the global pursuit of rendering construction materials reusable and more sustainable, the study of waste plastic modified asphalt represent an innovative research field. In addition to the use of reclaimed asphalt pavements to produce new roads, asphalt modifiers such as waste-plastic provide the possibility to recycle and reuse materials which are otherwise not biodegradable. Moreover, the introduction of plastics in hot mix asphalt mixtures has shown improved mechanical properties of pavements, particularly for what concerns stiffness and resistance to cracking. From the economical point of view, the addition of plastics reduces in turn the bitumen content in asphalt mixtures, thus decreasing the total cost of mixture materials as bitumen comes with an elevated price tag.  This study deals with the reuse of recycled polymers obtained from the processing of plastic waste in asphalt mixtures for road paving. Originating from common household plastic waste collected from the metropolitan city of Turin (Italy), plastic shreds were added to the asphalt mixtures by means of the dry method. The mixtures under scrutiny in this study were produced on real scale in a production plant, then collected during paving operations of a road section in Brandizzo (Piedmont), Italy. Three different asphalt mixtures for wearing course were produced with 24% reclaimed asphalt pavement (RAP), and varying dosages of waste plastic shreds: 0%, 0.5%, and 1%. The experimental laboratory activities serve to characterise and compare the various bituminous mixtures by investigating the compositional (volumetric & granulometric) and mechanical properties. In particular, Stiffness Modulus (IT-CY), Fatigue performance (IT-CY & CIT-CY), and Indirect Tensile Strength (ITS wet & dry) as per European standards EN 12697-23, EN 12697-24, and EN 12697-26, for both short- & long-term aged samples were investigated. The results allowed the evaluation of the effects of plastic content based on the mechanical properties obtained from the tests described above.  Furthermore, the research highlights the possible future benefits as well as the operational difficulties and environmental concerns surrounding the adoption of waste plastic modified mixtures in modern transportation infrastructures.