Concrete Building

Healthy concrete

Concrete is long-lasting and strong, but a collaboration with a hospital could help to make it more durable in harsh conditions.

Author

Cass Proudfoot

Deakin University has a lab full of concrete spa baths. These spa baths aren’t made of concrete, but rather they are spa baths to put pieces of concrete into. This is all part of a project to test salt water and weather effects on concrete, and to produce concrete that is more durable.

The corrosion of steel bars used in concrete construction is a major issue, and the team at Deakin is testing a plastic additive in the concrete mix, with the expectation that it will extend the service life of concrete buildings, pools and retaining walls.

The plastic they are using is high-grade single use plastic, left over from dialysis treatment in hospitals. This is ordinarily a waste product and with more than 12,000 Australians on dialysis, about 5,100 tonnes of this plastic waste is produced per year.

The concrete researchers, led by Dr Riyadh Al-Ameri, have added a two per cent measure of elongated plastic fibres to a normal concrete mix without removal of any original mix component. Dr Al-Ameri is a senior lecturer in structural engineering, and began his career working in concrete construction as a site engineer on large housing projects.

‘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 explains.

‘If we are able to facilitate the 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.’

The plastic they are using is left over from dialysis treatment in hospitals

The team has trialled various amounts of plastic fibres in the concrete mix, from 0.5 per cent, up to two percent plastic. ‘Since we are targeting structural concrete, we are very careful in the concrete mix proportions and shall conduct many tests to verify the concrete quality,’ Dr Al-Almeri says.

Given concrete’s long life, research on how it stands up to weather could be a slow process. So the team has created a purpose-built accelerated weather station at Deakin’s School of Engineering to simulate harsh marine weather exposure.

‘One month in the lab is equivalent to approximately one year outside, so we can observe the behaviour of the material quickly and efficiently,’ Dr Al-Ameri says.

‘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.’

The test results are very promising, showing a 30 per cent reduction in the water absorption rate in concrete with added plastic waste fibres, a significant change. And importantly there was no significant reduction in concrete compressive and tensile strength.

The potential to gainfully reuse single-use plastic and create a concrete product with qualities superior to current concrete products is hugely exciting for Dr Al-Ameri. The testing continues under ever more rigorous conditions, and if all goes well, a commercially available version of this concrete could be on the market in 2019.

Dr Al-Ameri

Dr Al-Ameri in Deakin’s Waurn Ponds concrete lab
Photo courtesy Donna Squire

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