Closing the loop: turning installation waste into new products

Reflection Friday: ♻️

Commercial & Strategic Value

• Environmentally Friendly: Provides telecommunications network operators with environmentally friendly micro-duct options.

• Supply Chain Resilience: Re-integrating localised waste streams hedges manufacturing operations against global virgin polymer price volatility and international shipping delays.

• Elimination of Downcycling: Establishes a true closed-loop model where high-value technical plastic remains in high-value technical applications indefinitely.
  

Conclusion

Korari Plastics’ closed-loop micro duct initiative proves that environmental circularity and high-performance telecommunications engineering are mutually achievable. By coupling co-extrusion manufacturing with a take-back programme, Korari Plastics offers a scalable, sustainable pathway for modern digital infrastructure deployment.

Developing integrated recycling and manufacturing systems starts with businesses taking a fresh look at the materials they produce, use and recover.

Korari Plastics in Paengaroa, Bay of Plenty, is putting this into practice, working with network operator RexNetworks to recover HDPE fibre optic micro duct offcuts and installation scrap for use in new duct manufacturing.

Case Study: Closed-Loop Circularity in Fibre Micro Duct Manufacturing

Company: Korari Plastics Limited
Location: Paengaroa, Bay of Plenty, New Zealand
Product Focus: High-Density Polyethylene (HDPE) Fibre Optic Micro Duct
Initiative Objective: Transition from traditional virgin HDPE micro duct production to a 100% closed-loop circular model—capturing post-installation offcuts, site scrap, and civil trenching waste to re-introduce high-grade recycled resin directly back into micro duct jacket manufacturing without compromising structural integrity or fibre blowing distances.

Summary: Telecommunications infrastructure expansion creates substantial demand for High-Density Polyethylene (HDPE) micro ducting. However, civil installation methods—including horizontal directional drilling (HDD), vibratory plowing, and micro-trenching—generate considerable volume in short reel-ends, trenching scrap, and installation offcuts. Traditionally, this material was sent to landfills or some plant waste sent to third party long distance recyclers.

Korari Plastics, based in Paengaroa, New Zealand, developed a fully integrated closed-loop recycling and co-extrusion framework. By regrinding internal manufacturing waste and RexNetworks’ post-installation HDPE scrap, Korari Plastics re-introduces recycled content into the structural outer wall of its fibre micro ducts while maintaining a virgin-grade, low-friction inner lining for optimal fibre jetting.

Industry Challenge & Material Risk

Fibre optic micro ducts are engineered conduit systems subject to rigorous physical requirements. To facilitate efficient blown fibre deployment (ABF), micro ducts must satisfy strict operational thresholds:

• Internal Friction Management: High inner-wall friction severely degrades air-assisted fibre blowing distances, increasing installation time and splicing requirements.

• Internal Pressure & Burst Resistance: Ducts must withstand blowing pressures of up to 10–15 bar without swelling or rupturing.

• Mechanical & Environmental Integrity: Direct-bury and micro-trenching applications demand high ring stiffness and resistance to environmental stress cracking (ESCR).

Historically, integrating recycled HDPE into single-layer micro duct extrusion led to inconsistent melt flow index (MFI) rates and surface roughness, resulting in downcycling rather than true circular re-manufacturing.

The Closed-Loop Lifecycle Framework

Stage 1: Multi-Layer Co-Extrusion Engineering
Korari Plastics solves the material performance challenge through multi-layer co-extrusion processing:

• Outer Structural Layer: Extruded using up to 100% high-purity recycled HDPE regrind (post-industrial and post-consumer scrap). This layer delivers required ring stiffness, impact resistance.

• Inner Performance Layer: Extruded using ultra-smooth, low-friction virgin polymer or modified slip-agent linings to guarantee uncompromised fibre blowing speeds and distances.
  

Stage 2: On-Site Collection & Take-Back Operations
In partnership with RexNetworks a network operator, Korari Plastics has implemented site-level material recovery:

• Dedicated Staging Bag: Collection bags are located with RexNetworks.

• Captured Waste Stream: Reel-ends, trenching offcuts, test sections, and damaged ducting are consolidated and transported to the Paengaroa facility.
  

Stage 3: Granulation, Quality Testing & Re-Integration
Recovered micro ducts undergo strict reprocessing steps prior to re-extrusion:

1. Granulation & Washing: Scrap ducting is stripped, shredded and processed into clean, high-density regrind.

2. Primary Line Re-Integration: Verified regrind is fed directly into the outer-wall extruders as primary feedstock.

Performance & Impact Metrics