Thermoplastic Post-Consumer Recyclates for Buried Infrastructure: Barriers, Classification Gaps, and a Path Toward Quality-Assured Use.

With the Green Deal and the Circular Economy Action Plan, the European Union aims to replace half of the fossil-based raw materials in plastics with sustainable alternatives by 2030. In the plastic pipe industry, the use of post-consumer recyclates (PCRs) remains very limited due to reduced material quality, economic hurdles, limited availability, non-specific classification requirements, and a lack of testing standards. This paper presents two interconnected contributions to the quality-assured use of PCR for buried utility infrastructure made from Polyethylene (PE), Polypropylene (PP), and unplasticized Polyvinyl Chloride (PVC-U). First, a methodological framework, based on EN 13476, defines suitability as the intersection of material classification and application-specific requirements profile. A review of the current regulatory and technical situation reveals a systemic discrepancy: requirements profiles are oriented toward virgin material, while the scope of classification for PCR remains insufficiently defined. As a result, PCR is either used without adequate suitability assessment or blended with fillers, thereby limiting recyclability. Secondly, the review focuses on additive strategies, including restabilization, compatibilization, chain modification, and recyclate-compatible functional additives. These strategies are among the main technical solutions for closing the gap between PCR properties and the product's requirements, reducing filler dependency, and enabling the long-term use of PCR in safety-critical applications.