Deakin project uses plastic dialysis waste to produce durable concrete

Dialysis patients could inadvertently improve sustainability in the construction industry, thanks to an innovative Deakin University recycling project that’s turning hospital waste into longer-lasting concrete.

A team at Deakin’s School of Engineering is behind the new project, which could ultimately save from the scrap heap the thousands of tonnes of plastic waste created in Australia each year through dialysis treatment.

Project leader Dr Riyadh Al-Ameri, a senior lecturer in structural engineering, said the project could solve two problems in one, with corrosion of steel bars used in concrete construction a major issue for the industry.

The project is a collaboration between Dr Al-Ameri and nephrologists Dr Katherine Barraclough from the Royal Melbourne Hospital and Professor John Agar from Barwon Health’s University Hospital Geelong, and came about when the specialists approached Deakin to find a practical solution to their waste issue.

Dr Al-Ameri said his project team was hoping to use the shredded plastic waste to help better protect structural concrete from corrosion.

“Concrete can crack and damage the internal bond, which can then lead to water penetration and corrosion of the steel bars, critical for providing the strength and integrity of concrete structures.

“If we are able to facilitate production of new types of concrete that will offer better protection, give structures longer life and better performance, as well as help recycle plastic waste, that will be a great achievement.”

Dr Barraclough said each dialysis treatment created between one and three kilograms of plastic waste, and with more than 12,000 Australians on dialysis, that added up to about 5,100 tonnes of plastic waste per year.

“Haemodialysis (the most common type of dialysis) involves making a circuit where blood is pumped from a patient’s bloodstream through a machine then back to the patient. This removes toxins and excess water and is life sustaining for patients with kidney failure,” she said.

“For safety reasons, both the tubes that carry the blood and the dialyser (the part of the machine that cleans the blood) are made of plastic designed for single use only. The result is large amounts of plastic waste generated from each dialysis treatment.

“Because the waste is potentially infectious, it must be either burnt or sterilised before being thrown away. This not only costs a lot of money, but also causes significant harm to the environment.”

As part of some initial testing, Dr Al-Ameri’s team added the shredded plastic waste to a concrete mix at concentrations of 0.5 per cent and 1 per cent by weight of concrete, with results showing this made a product that was more durable and significantly more water-proof.

Going forward, Dr Al-Ameri and his team hope to conduct more rigorous testing to see if this new concrete mix can stand up to harsh conditions.

“We will use our accelerated weather corrosion tanks in the concrete lab to simulate a marine environment,” Dr Al-Ameri said.

“One month in the lab is equivalent to approximately one year outside, so we can observe the behaviour of the material quickly and efficiently.

“Wet and dry cycles can have a big impact on the durability of the concrete, and sea water has chloride, which is very harmful to both concrete and steel reinforcement.

“So we’re looking for innovations that will help concrete construction of off shore rigs for oil and gas, observation towers, concrete buildings in coastal areas that are exposed to humidity, and marine structures such as retaining walls that are in contact with water.”

Pictured: Deakin University School of Engineering PhD candidate Aifang Wei and project leader Dr Riyadh Al-Ameri.

Photo credit: Donna Squire

A new dimension of plastics recycling

Deakin University researchers have run a successful trial in using waste plastics for the raw material in 3D printing, known as EcoPrint – a technology that has exciting potential for communities impacted by poverty or natural disasters.

Global plastic production is increasing rapidly, building on a steady 50-year growth trajectory. In 2013, some 299 million tonnes of plastics were produced, the popularity of it stemming from its qualities of being lightweight, durable and suitable for diverse applications.

However, this has inherent impacts for the environment, as disposal and recycling of this complex material has become one of the biggest challenges of the modern age. Australian recycling organisations highlight that plastic is the most abundant item of rubbish found during ‘Clean Up Australia’ days, representing 30 per cent of all rubbish collected over the last 10 years.

Against this backdrop, Professor Mazher Mohammed and a group of his students have worked on a project to reconstitute plastic waste as printer filament, the feedstock for 3D printing.

Mazher joined Deakin University’s School of Engineering in January 2015, taking on the lecturing role as Research Fellow for Engineering Sustainability.

“We teach students about matters relating to sustainability in the world around us with an emphasis on engineering solutions,” he says.

Through the course of doing his job, and with his background in 3D printing, Mazher starting thinking about the main commercial products in 3D printing being plastic based. Plastic is made from oil, which is a finite resource and potentially going to be depleted in the future.

In addition, Mazher says that as plastic is so prevalent in everyday items from devices to packaging, it’s an important material for engineering, as well being a resource that the world needs to manage wisely.

“I wondered if we could come up with a system to take spent plastic materials, reconstitute those to use in 3D printing to manufacture new end-products,” explains Mazher.

In short, the study was built on a desire to produce usable plastic filament as a viable means of consuming waste plastics and reduce the amount sent to landfill.

From there, Mazher said he was keen to get material for the project as cheaply as possible or for free.

In 3D printing, the prints can fail and those failed prints normally end up in the bin, which can generate substantial volumes of waste plastic. Moreover, when students work on 3D printing projects to make parts, when the project is over, they end up redundant and, again, ended up as waste.

“The logical thought followed of could we take those waste streams as a feedstock to explore the idea of recycling ABS plastic in our project, and converting that into plastic filament for printing,” Mazher says.

Another material source Mazher identified was all the HDPE milk cartons the School uses for its coffees.

“That led to me thinking that this is another free resource, so could we take these HDPE cartons and do the same thing as we were planning with scrap ABS plastics,” he says. “That became the premise for the project for two of our students.”

Around the same time, Mazher’s team became aware of local business GT Recycling. They wanted to go beyond a grassroots research-based project.

“We wanted to develop a viable commercial venture in itself, where we could look to reinvigorate the local manufacturing scene in Geelong, which has suffered a huge decline due to the closure of the Ford plant,” Mazher adds.

As a result, they thought with the local infrastructure available through GT Recycling, which processes large volumes of plastics waste and granulate it into a feedstock they could use, this could be the start of such a venture.

To read more, see page 22 of Issue 10.