Valorisation des plastiques recyclés dans les enrobés bitumineux en climat tropical humide : étude expérimentale appliquée au contexte de la République Démocratique du Congo

The Democratic Republic of Congo simultaneously faces a substantial increase in plastic waste and an accelerated deterioration of its road network. This experimental study investigates the feasibility of integrating recycled plastics (polyethylene and polypropylene) as additives in bituminous asphalt mixes to improve their mechanical, thermal, and environmental performance under humid tropical climate conditions. Mixes containing 0%, 4%, 6%, 8%, and 10% of plastic were produced using the wet process method and tested for Marshall stability, ductility, moisture susceptibility, thermal resistance, and accelerated aging. Results indicate that a 6% plastic incorporation increases Marshall stability by 18.1%, enhances moisture resistance by 15%, and potentially extends road service life by 4 to 6 years. The study demonstrates the technical and ecological relevance of this approach and lays the foundation for future national standardization. Recommendations include the implementation of pilot road sections, the development of a Congolese technical guideline, and its integration into the national circular economy strategy.