Making concrete from dialysis waste

From adding carbon dioxide by-products to living bacteria into concrete mixtures, scientists around the world are coming up with more ways to not only make building materials of the future more durable, but also help promote environmental sustainability by turning waste into useful products.

This time, a team of experts at Deakin University’s School of Engineering has embarked on a mission to turn thousands of tonnes of plastic waste from dialysis treatments that would otherwise go into the scrap heap each year, into durable concrete.

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

Dr Al-Ameri, who is leading the project, says his team was hoping to use 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,” he says.

“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.”

Waste not, want not

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

“Haemodialysis 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 explains.

“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.

“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.”

Concrete strengthening with plastic

During the initial testing phase, Dr Al-Ameri’s team added the shredded plastic waste to a concrete mix at concentrations of 0.5 per cent and one per cent by weight of concrete, with the results being a product that was more durable and significantly more waterproof.

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

With funding from global provider of dialysis products and services, Fresenius Medical Care, 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 says.

“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.”