Australian researchers use plastic dialysis scrap to produce durable concrete

Pictured from left: Aifang Wei, a PhD student at Deakin University, and Dr. Riyadh Al-Ameri, a Deakin University senior lecturer in structural engineering. (Photo by Donna Squire, Deakin University)

Dialysis patients could inadvertently improve sustainability in the construction industry, thanks to a Deakin University, Burwood, Australia, recycling project that’s turning hospital scrap 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 tons of plastic scrap created in Australia each year through dialysis treatment.

Project leader Dr. Riyadh Al-Ameri, a senior lecturer in structural engineering, says 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 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.

Al-Ameri says his project team was hoping to use the shredded plastic scrap 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."

Barraclough says each dialysis treatment created between 1 and 3 kilograms (2 to 5 pounds) of plastic scrap, and with more than 12,000 Australians on dialysis, that added up to about 5,100 metric tons of plastic scrap 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 says.

"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 scrap generated from each dialysis treatment.

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

"With increasing numbers of people requiring dialysis in Australia and worldwide, we need to work out ways to reduce the costs of care delivery, as well as play our part in ensuring a healthy environment for future generations."

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

"The 30 percent decrease in water absorption we found is significant and would be expected to improve resistance of concrete to corrosion," Dr Al-Ameri says.

Now thanks to funding from industry partner Fresenius Medical Care, a Germany-based global provider of dialysis products and services, 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," Al-Ameri says. "One month in the lab is equivalent to approximately one year outside, so we can observe the behavior of the material quickly and efficiently.

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

"So we're looking for innovations that will help concrete construction of offshore 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."