A new independent, expert review on the use of recycled materials in road and rail infrastructure has shown that materials such as plastic and organic food waste can improve the performance of said infrastructure and help further Australia’s circular economy. 

The report by the Australian Road Research Board (ARRB) said the industry can now have more confidence in incorporating waste materials such as plastic, glass, organic food waste and tyre rubber in building Australia’s roads and railways.

Plastic can be used for applications such as building noise walls, while organic food waste was earmarked for more widespread use in landscaping and erosion control.

ARRB said using more recycled materials in the construction, rehabilitation and maintenance of road and rail infrastructure has a host of benefits for Australia, including less waste sent to landfill, lower greenhouse gas emissions, job creation and better, more durable roads.

Despite a long history of using recycled materials in infrastructure, it’s still not business-as-usual within roads and rail.

The report said the reasons include lack of awareness and education, disconnection between market demand and supply, lack of specifications and guidelines, and most importantly, lack of consistent and scientific evidence to report on longer-term performance and sustainability benefits. That’s something ARRB said should change as a result of this report.

The report said:

“This project provides robust, evidence-based knowledge on how to optimise the uptake of recycled materials in infrastructure projects.

“There is ample opportunity to increase (recycled materials) content within transport infrastructure applications, or even the frequency that they are used.

“There are also emerging recycled materials technologies that have significant opportunity for increased uptake. Improved awareness and education in how these materials are used, supported by policy and procurement drivers, new and improved specifications and more modern recycling facilities with increased capacity, can all contribute to increases in the use of recycled materials, sustainability outcomes and a more circular economy.”

Commissioned by the Federal Government’s Department of Climate Change, Energy, the Environment and Water, the report examined ten recycled materials for their potential use within road and rail infrastructure. 

They were crushed concrete and brick, crushed glass, reclaimed asphalt pavement or RAP, crumb rubber, ground granulated blast furnace slag, fly ash, bottom ash, recycled organics, recycled ballast and recycled plastics.

The report, in two parts, shows significant economic and environmental benefits for the majority of recycled materials in road and rail infrastructure.

The report said the transformation of road and rail infrastructure to include recycled materials “will generate long-term economic benefits, lower carbon emissions and help deliver a circular economy”.

The benefits of incorporating recycled materials into the construction, rehabilitation and maintenance of roads and rail infrastructure can provide comparative benefits, including: 

  • Reducing the amount of waste sent to landfill
  • Reducing illegal dumping and littering
  • Reducing the greenhouse gas (GHG) emissions generated by the production of new materials and the disposal of waste materials
  • Reducing our reliance on non-renewable and imported resources
  • Developing a circular economy in which materials are continually reused in their highest and best usage
  • Creating new and enhancing existing markets and creating new jobs
  • Reducing whole-of-life infrastructure costs
  • Improving asset durability and performance

Other key findings included environmental and economic benefits. 

Significant environmental benefits can be expected for the majority of recycled material applications in road and rail infrastructure.  

Greenhouse gas (GHG) emission reductions range from 47 per cent to as high as 98 per cent, and overall environmental improvements between 59 per cent to 99 per cent measured as reductions in Enviropoint score.

On the environmental impact measures, the best-performing recycled materials were:

  • The use of reclaimed asphalt pavement (RAP) in surface and base layers as a replacement for asphalt made with virgin aggregates and binders 

98 per cent fewer GHG emissions and 99 per cent lower Enviropoint score

  • the use of fly ash as a replacement for hydrated lime and cement in stabilised asphalts and concrete pavements
  • 98 per cent fewer GHG emissions and 98 per cent lower Enviropoint score

Cost savings also ranged from two per cent to 83 per cent where the most cost-effective recycled material is RAP. Notably, bottom ash presently does not have a market value, so the material cost is assumed to be zero.

The full details of the report can be found here.

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