By GNA Editor

‍Opinion Pieces by Marc Amtsberg (Atarfil) and John Scheirs (ExcelPlas)

Marc has spent 20 years of working in the Geosynthetic sector as both a client and working with major manufacturers and he has observed an ongoing challenge across the industry. Marc has found that remains a general lack of focus on both the Geosynthetic Inputs and Manufacturing Processes that are so critical to product design life.

John has been testing polymers and geosynthetics for 30 years and he has pioneered some of the industry’s latest testing to evaluate long-term durability such as deformulation testing of additives in geosynthetics, thin-film accelerated immersion testing and the use of strain hardening modulus as a surrogate for the NCTL stress cracking resistance test.

An evaluation of the raw material and manufacturing process provide the key insight into expected Geosynthetic performance. Yet this is often overlooked in academic studies, in critical project testing, even for projects that require accountability in EPA regulations.

A reputable manufacturer will have extensive data and must be willing to identify their raw material supplier, their quality processes. If not willing to reveal their polymer inputs, demonstrated testing and project history then serious doubts should be raised over the suitability of their materials.

The fundamental challenge in using Geosynthetics, is short term testing on very small samples is being used to make performance assumptions for projects that can be millions of square metres. This assumption is only correct, if the product properties are replicated across every square metre. A designer who invests time to understand product inputs and manufacturing process, is better equipped to understand this project risk.

In this new GNA series, Marc and John document the most common technical questions encountered for common landfill and mining geosynthetic lining systems. Many of these properties are not measured by QC Testing, but nevertheless are critical in determining Geosynthetic product life.

Introduction

In recent years, there has been a growing emphasis on sustainable practices and environmental stewardship across various industries. The use of recycled materials, including polymers, has gained considerable attention as a means to reduce waste and minimize the reliance on virgin resources. However, concerns have been raised regarding the performance of products made from recycled content compared to those made from virgin materials. This article aims to address the performance of recycled polymer-based non-woven geotextiles and compare them to geotextiles made from virgin polymer.

Non-Woven Geotextiles and Performance Considerations

Non-woven geotextiles are versatile materials extensively used in civil and environmental engineering applications. They serve various functions such as separation, filtration, drainage, and reinforcement. One critical performance aspect of non-woven geotextiles is their ability to withstand sustained tensile loads and resist excessive axial deformation, known as creep behaviour.

The creep behaviour of non-woven geotextiles is a crucial parameter to consider in design, as excessive deformation can lead to failure. Previous studies have shown that the properties of non-woven geotextiles, including their creep behaviour, can be modified when subjected to tensile loads. Thus, it is essential to understand the behaviour of these geotextiles under sustained axial loads.

Recycled Content in Geotextiles

In the case of geotextiles, specifically non-woven needle-punched geotextiles, made from recycled poly(ethylene) terephthalate (PET) yarns/filaments, a comparative study was conducted by Fleury et al. (2021) to evaluate their performance against geotextiles manufactured from virgin PET. Two types of geotextiles were investigated: one with continuous filaments (GTXnwC) and the other with short-staple fibres (GTXnwS).

The study by Fleury et al. (2021) focused on analyzing the creep behaviour of these geotextiles under sustained tensile loads. The results indicated that the non-woven geotextiles manufactured from recycled PET exhibited creep strains with similar behaviour and magnitudes as geotextiles made from virgin PET. The variability in the creep behaviour of the recycled geotextiles increased with higher applied load levels, influenced by the structural response of each specimen.

Implications for Recycled Content Usage

Based on the conclusions drawn from this study, it is evident that non-woven geotextiles manufactured using recycled PET can achieve comparable performance to those made from virgin PET. These findings support the notion that recycled content can be effectively utilized in geotechnical works, such as civil and environmental engineering projects.

Moreover, it is crucial for procurement policies across government, civil, landfill, and mining sectors to recognize and prioritize the demand for recycled content. The observed equivalency in performance between recycled and virgin geotextiles highlights the potential of recycled materials in meeting environmental, social, and governance (ESG) objectives.

Conclusions

The study on non-woven geotextiles manufactured with recycled PET yarns/filaments demonstrates that these materials can perform at a similar level to their virgin counterparts. The creep behaviour, which is critical for geotextile performance, showed comparable strains and magnitudes when compared to virgin geotextiles.

Therefore, if a geotextile source with recycled material is available, it is essential to assess the raw material quality and consider finished product data performance through direct comparison to virgin materials. This evaluation process ensures that the recycled content meets the required standards and specifications, supporting sustainable practices and reducing reliance on virgin resources.

The findings of this study provide confidence in utilizing recycled content in non-woven geotextiles, reinforcing the growing preference for recycled materials in the context of ESG policies and sustainable procurement practices.