Soft plastics used to create sustainable concrete carpark and footpath

Image of the Coles carpark construction courtesy of Replas.

A team of engineers from RMIT have partnered with Victorian recycling organisations Replas, RED Group and SR Engineering to create a concrete material made from recycled soft plastics.

Each day 1.3 million pieces of soft plastics are returned by Australians to REDcycle recycling bins across the country. Though wrappers, cling wraps and plastic bags are problematic to recycle.

In an effort to find another stream for these soft plastics to be reused, the RMIT team worked with industry to use Polyrok, a plastic aggregate made from soft plastics, in a concrete carpark and footpath in Frankston.

In collaboration with Replas, RED Group and SR Engineering the team were able to develop a mix methodology and material characterisation to include Polyrok.

The concrete mix design optimised the strength and acoustic energy absorption of the material.

Team leader, RMIT’s Dr. Jonathan Tran said glass can be easily recycled and turned into things such as sand replacement, but plastic is much harder.

“Mixing concrete and plastic is difficult, as the two don’t naturally bond,” he said.

“Replas and SR Engineering came to RMIT because of our unique facilities to develop the best way to bond the two components together.”

Tran said the opportunity to work with industry and create a considerable impact to society was a rewarding experience.

“Since the partnership, our industry partners Replas, RED Group and Coles have diverted over 1.3 billion pieces of soft plastic from landfill,” he said.

Tran said there is the potential for 105,000 tonnes of soft plastics to be converted into the dense plastic aggregate every year in a local factory in Melbourne.

The application of the sustainable concrete in the Coles car park in Horsham saw over 900,000 pieces of plastic packaging used in the concrete.

“In the future, we’re hoping to explore the production of sustainable concrete structures using a new large-scale concrete 3D printer at RMIT’s Bundoora campus.”

The project was led by Senior Lecturer Dr Jonathan Tran from the School of Engineering with support from two research fellows, Dr Rajeev Roychand and Dr Thomas Loh.