Recycled plastic noise barrier walls

The outcome

Noise barriers are structures designed and installed to protect residential areas from noise pollution and are an effective technique to mitigate noise pollution from roadway, railway and other industrial noise sources.

Combining the engineering knowledge of the research team at the University of Melbourne and the industrial experience of Integrated Recycling (IR), the project aimed to optimise and verify the performance of a new noise wall product made only from recycled plastics with minimal usage of virgin materials as required additives.

This project demonstrated the infield performance of noise barrier walls made from approximately 85% recycled plastics for the fast growing outdoor noise barrier market. While there are other recycled plastic walls in the market, IR‘s product is unique globally due to its high percentage of recycled plastic content.

The constructed noise wall barrier showed successful performance against most of the standard requirements at a national and international level. The product met mechanical objectives for flexural strength and stiffness, while demonstrating sound transmission loss to required guidelines and minimal UV accelerated weathering.

The monitoring of the noise wall site in Reservoir has provided additional product validation information including data on structural integrity, impact resistance and strength verification against vandalism and fire safety.

The research demonstrated the design life of recycled plastic noise walls can be longer than traditional noise walls, extending the benefits to other sectors in urban development, road and rail authorities and local councils.

The need

Noise walls are one of the most significant visual elements in highway and rail corridors and their cost can be a significant proportion of the construction budget. Currently, virgin materials such as concrete, timber and virgin plastic are the most common materials used for manufacturing noise barriers – all of which leave a significant carbon footprint due to the extraction and production processes involved.

This project showed that recycled plastic sourced from flexible agricultural plastic waste is a suitable replacement for virgin materials in noise wall products. The utilisation of recycled materials in these products has the potential to:

• divert significant amounts of plastic waste from landfill
• build local end markets for low grade mixed plastic
• reduce dependence on virgin and finite resources such as timber.

Developing the solution

The project was delivered in 3 phases.

Stage 1

Laboratory testing was done to determine the most suitable blend of recycled plastic to satisfy the current national and international requirements for noise barriers. The noise wall product contains a mix of plastic polymers including LDPE and PS.

Stage 2

Noise barrier wall manufacturing and a field trial installation were then completed. Integrated Recycling manufactured a full-scale prototype of the noise barrier wall which was installed at their Reservoir site in December 2021.

Stage 3

Field monitoring and performance analysis was conducted to monitor the performance of the real size noise barrier walls against identified criteria including sound transmission loss, UV acceleration and weathering, fire testing and flexural strength.

The laboratory testing and field monitoring showed that recycled plastic noise wall panels are a safe and effective material for noise walls.

The partnership

The research team at the University of Melbourne has extensive experience in using recycled material in engineering applications, completing major projects using recycled material in the pavement and civil engineering applications, construction, green building and smart cities.

The industry partner, Integrated Recycling, manufactures a range of composite recycled plastic products at its Mildura factory in north-western Victoria. Integrated Recycling is working on a mass production manufacturing line to build their production capacity for large scale projects.

Pathway to commercialisation

A life cycle assessment conducted by IR shows that their products are low in carbon emissions to make. But market insights gathered by IR indicate that further product validation such as cost-benefit analysis and understanding urban aesthetics are needed to support commercial pathways.

Both project partners have identified the potential in utilising the recycled plastic product as a retaining wall panel suitable for local governments and in industrial precinct developments. Further testing will be needed to validate this application.

Gallery

More information

For more about this project, email marketsacceleration@sustainability.vic.gov.au