Australia’s construction sector must embrace the circular economy, a leader in construction innovation says.

Speaking at a recent session hosted by the Victorian Local Association of the Institute of Civil Engineers in Melbourne, Professor Priyan Mendis, Professor of Civil Engineering at the University of Melbourne, said that Australia’s building sector has enormous opportunities to eliminate waste and to transition to a circular economy mode of operation.

According to Mendis, the importance of action should not be underestimated.

With global temperatures on the rise and the concentration of carbon in the atmosphere having risen from less than 320 million parts per million in 1960 to a record 414.72 parts per million in 2021, Mendes says the importance of meeting Australia’s climate change commitments should not be underestimated.

As those who design and construct buildings, infrastructure and cities, he says architects, engineers and builders are critical in achieving this.

Further, Mendis says the sector needs to address the volume of waste which it generates and ends up in landfill.

According to the National Waste Report 2020, Australia’s construction and demolition industry generated about 27 million tonnes of waste.

At this level, construction and demolition accounts for around 44 percent of the nation’s overall 62 million tonnes of ‘core’ waste or 36 percent of the 74 million tonnes of overall waste and ash combined.

Of the 27 million tonnes in construction and demolition waste which is generated, around 12 million or 36 percent is going into landfill.

Should nothing be done, the problem will become worse as demand for housing and infrastructure increases. Already, Australia’s volume of construction/demolition waste generated has increased by more than 32 percent since 2010.

Moreover, experience overseas suggests that Australia has potential to improve.  At 58 percent, our current recycling rates are above New Zealand (28 percent), the US (48 percent) and the UK (54 percent) but are well below rates being achieved in Denmark (90 percent) and Norway (80 percent).

To address this, Mendis says Australia’s construction sector needs to adopt circular economy thinking.

Whereas the traditional ‘linear economy’ involves materials going from resource extraction through to production, consumption and then disposal (often through landfill), a circular economy approach involves waste being effectively managed after consumption and either recycled or reused as secondary materials where possible.

To implement such an approach, Mendis sees opportunities in (a) prefabrication and (b) sustainable applications of recycled materials.

Prefabrication is a process which sees either entire buildings or parts of buildings manufactured in a factory before being transported to site. This can be done using either two-dimensional panels or by manufacturing three-dimensional modular units.

This form of building is gaining in popularity as it offers faster construction times (especially as modules can be fabricated in the factory at the same time as foundations are being laid on site) along with the improvements in quality and safety which can be associated with fabrication occurring in a controlled environment.

From a circular economy and waste point of view, prefabrication can not only avoid generation of onsite waste but can enable buildings and building parts to be designed to be disassembled and reused or recycled after the building or structure has been decommissioned.

Beyond that, Mendis sees opportunities for materials to be recycled and reused in sustainable applications.

A substantial volume of work is being done in this area through the ARC Industry Transformation Research Hub- Transformation of Reclaimed Waste Resources to Engineering Materials and Solutions for a Circular Economy (TREMS), of which Mendis is a Deputy Director.

TREMS is a research hub led by Melbourne University and RMIT which brings together scientists, researchers and industrial experts from universities as well as state, industry and international partners. It is exploring new ways to engineer construction and high other high value materials from recycled household, commercial and industrial waste.

Currently, TREMS is involved in 25 projects and initiatives – 13 of which involve development of smart materials, products and solutions.

In one such project, TERMS is working with Sri Lankan based advanced material company Ceylon Graphene Technologies on a solution which aims to enable greater use of waste materials in concrete by use of ‘graphene concrete’.

This involves the addition of graphene oxide to the waste materials to improve the strength and water/abrasion resistance of the concrete (refer presentation for details).  This will enable production of ‘blended waste concrete’ which will contain a range of waste materials plastic, rubber, crushed glass, bottom ash, recycled concrete aggregates, textiles and hair) along with the graphene oxide but will have greater strength and abrasion resistance compared with conventional concrete.

It will enable greater substitution of cement in concrete production with waste materials whilst offsetting the loss of strength which is typically associated with this substitution. This is important as cement production is responsible for 8 percent of the world’s carbon emissions.

The graphene is being sourced in Sri Lanka, which has the purest form of graphene in the world.

In another project, the hub is working with plastics recycler Advanced Circular Polymers through its Somerton factory to develop a smart AI automation and upcycling solution for plastic recycling with advanced circular polymers to produce materials such as recycled plastic pods for house foundations.

A third project involves converting solar panel waste to construction materials. Though this project solar panel upcycling plant operator Elecsome based in the Victorian town of Kilmore is recovering components used on solar panels such as glass, silicon, polymers, aluminium, copper and silver and to transform these into premium end-user projects such as high-grade concrete, construction feedstock and recyclable consumables.

This is important as solar panels are expected to generate 1.5 million tonnes of waste modules throughout Australia between now and 2050.

Finally, a fourth project involves a process through which discarded cladding from flammable aluminium composite panels is transformed into value added materials.

The process separates the aluminium skin of the panels from the core via a flame which heats the cladding and separates the aluminium skin from the polyethylene core. This will then be used to make products such as prefabricated panels and shoes.

Mendis’ presentation was given at a session hosted by the Victorian Local Association of the Institute of Civil Engineers last month.

The event was held at the Melbourne office of multi-disciplinary design and engineering firm Arup, who sponsored the event.

As well as Mendis, another presentation was given by Professor Syahaida Ismail, an Associate Professor of Civil Engineering at Universiti Teknologi Malaysia (University Technology Malaysia) in Malaysia and a research fellow with the Australian APEC Study Centre hosted by the University of Melbourne.

In her presentation, Ismail shared how architects, engineers and builders could reinvent design thinking through biophilic concepts.