Where Low-Cost Products Often Cut Corners 

Use of Recycled or Contaminated Resins – Understanding the Differences

Not all recycled materials are equal, and the term “recycling” is often used imprecisely in the geomembrane market. From a technical and risk-management perspective, it is essential to distinguish clearly between different types of recycled polymer content and their implications for long-term performance.

Controlled In-House Regrind (Process Scrap)

Standards such as GRI‑GM13, ASQUAL, BAM, DIBT, KIWA, etc. allow limited use of regrind generated during the manufacturing process (typically up to 10%). In practice, this is not only acceptable but operationally necessary. During extrusion and sheet calibration, edge trim (process scrap) is unavoidably produced and must be immediately reintroduced into the same product stream to avoid continuous waste generation. This material:

  • Originates exclusively from the same production line
  • Has never been installed or exposed to environmental influences
  • Retains its original additive and antioxidant package

  • Is reintroduced under controlled and traceable conditions

     

This regrind does not inherently compromise geomembrane performance and can contribute to manufacturing efficiency without increasing technical and long-term risk.

Post-Industrial Recycled (PIR) Materials

Post-industrial recycled resins originate from external industrial waste streams, such as off-spec products or trimming waste from unrelated plastic processes. While often marketed as “clean” recycling, PIR materials may present risks due to:

  • Unknown thermal history and multiple melt cycles
  • Partial depletion and consumption of stabilizers and antioxidants
  • Potential contamination from other polymers or additives

Without full traceability and rigorous qualification, PIR materials can introduce variability that significantly reduces stress crack resistance, weldability, and long-term durability.

Post-Consumer Recycled (PCR) Materials

Post-consumer recycled resins are derived from plastics that have completed their service life in consumer or industrial applications. Their use in geomembranes is explicitly prohibited by GRI‑GM13 and main other standards and guidelines due to fundamental and unavoidable risks, including:

  • Unknown and often harsh prior exposure (UV, chemicals, mechanical stress)
  • Severely depleted or exhausted antioxidant systems
  • High likelihood of contamination (other polymers, fillers, organic residues, heavy metals)
  • Unpredictable rheological and mechanical behavior

 

Even when blended at low percentages, PCR materials can significantly reduce oxidative stability, stress crack resistance, and service life. These deficiencies are often not detectable through standard short-term testing but manifest under long-term field conditions.

Contamination Risks and Hidden Defects

The introduction of external recycled materials, particularly PIR or PCR substantially increases the probability of:

  • Gels, inclusions, and unmelted particles
  • In-plane weaknesses or localized embrittlement
  • Increased pinhole formation during extrusion

  • Reduced consistency in textured surface performance

     

Such defects may remain visually undetected during installation yet act as stress concentrators, accelerating premature failure.

Why This Matters for Long-Term Performance

Geomembranes are expected to perform reliably for decades in chemically aggressive, mechanically demanding, and often safety-critical environments. Any reduction in material homogeneity, antioxidant stability, or molecular integrity directly undermines this expectation.

For this reason, AGRU strictly differentiates between controlled internal regrind and external recycled materials. While limited, well-managed regrind can be part of a responsible manufacturing process, the use of post-consumer or poorly qualified recycled resins represents a fundamental risk to long-term performance and regulatory compliance.