When Physical Chemistry Meets Circular Economy to Solve Environmental Issues: How the ReScA Project Aims at Using Waste Pyrolysis Products to Improve and Rejuvenate Bitumens

Urban waste management is a hard task: more than 30% of the world's total production ofMunicipal Solid Wastes (MSW) is not adequately handled, with landfilling remaining as a commonpractice. Another source of wastes is the road pavement industry: with a service life of about10-15 years, asphalts become stiff, susceptible to cracks, and therefore no longer adapted for roadpaving, so they become wastes. To simultaneously solve these problems, a circular economy-basedapproach is proposed by the ReScA project, suggesting the use of pyrolysis to treat MSW (or itsfractions as Refuse Derived Fuels, RDFs), whose residues (oil and char) can be used as addedvalueingredients for the asphalt cycle. Char can be used to prepare better performing and durableasphalts, and oil can be used to regenerate exhaust asphalts, avoiding their landfilling. The proposedapproach provides a different and more useful pathway in the end-of-waste (EoW) cycle of urbanwastes. This proof of concept is suggested by the following two observations: (i) char is made upby carbonaceous particles highly compatible with the organic nature of bitumens, so its additioncan reinforce the overall bitumen structure, increasing its mechanical properties and slowing downthe molecular kinetics of its aging process; (ii) oil is rich in hydrocarbons, so it can enrich the poorfraction of the maltene phase in exhaust asphalts. These hypotheses have been proved by testing theresidues derived from the pyrolysis of RDFs for the improvement of mechanical characteristics of arepresentative bitumen sample and its regeneration after aging. The proposed approach is suggestedby the physico-chemical study of the materials involved, and aims to show how the chemicalknowledge of complex systems, like bituminous materials, can help in solving environmental issues.We hope that this approach will be considered as a model method for the future.