New flexible solution for old rubber tyres

Flexiroc and Tyre Stewardship Australia join forces to ramp up Australia’s use of end-of-life tyres.

Australian entrepreneur Gary Bullock has come up with an ingenious way to make buildings fire and blast-proof.

His invention, Protectiflex, is a concrete material that combines recycled rubber tyres and composite fibres in a cement matrix that can be sprayed onto buildings.

Bullock, a structural engineer, established his company Flexiroc Australia in 2014, after he bought the rights to a rubber concrete made from recycled tyres.

The company is recycling 10,000 tyres from Australia and another 500,000 tyres from around the world to include in blast-proof materials.

Protectiflex has been tested at Australia’s national blast facility at the University of Wollongong and has so far delivered results beyond Bullock’s expectations.

“In a normal explosion, that block work would disintegrate,” he explained.

“What it does is it takes all the energy from the blast and it holds it all together.

“So effectively, it’s enhancing the blast protection of that wall. If you have an existing wall, it means you can spray that wall and make it blast resistant.”

Blast testing at Australia’s only national blast simulation facility at the University of Wollongong. Image: Tyre Stewardship Australia

Protectiflex can be used for a wide range of purposes where blast protection is needed, such as defence, heavy industry and in the petrochemical industry.

It is also environmentally friendly, durable, light weight, and about 30 per cent lighter than concrete which can be used to make thinner lighter structures.

“You can apply this material to either to an existing building or to a new building and do it as part of the new building structure,” Bullock said. “Basically, it will enhance the blast resistance of that structure.”

Testing panels from various building parts made up of concrete masonry blocks are coated with a thin layer of thin, which enhanced brittle block works.

Professor Alex Remennikov from the University of Wollongong’s Faculty of Engineering said masonry walls form a common building component that are vulnerable to blast loads, created by terrorist attacks or accidental explosions.

“The blast simulation facility was established to overcome the challenges associated with live explosive testing, such as very high cost, safety, efficiency and repeatability of test results,” he said.

“We’ve used a blast simulator, which is the only available facility in Australia and the southern hemisphere for blast testing of elements of buildings.”

Protectiflex panels were tested at pressures 50 kilopascal and 100 kilopascals at the University of Wollongong, home to Australia’s only national blast simulation facility.

“These panels have demonstrated exceptional performance because they didn’t develop any damage, cracks, and stayed intact,” Remennikov said.

A coated masonry wall will endure far larger blast loads than a standard wall, Bullock said.

“We’re getting very good protection of the masonry wall with smaller deflections and it’s totally intact,” he said.

During test runs, sprayed Protectiflex walls were hit with shock loadings similar to a car bomb explosion from 20 metres away.

Protectiflex combines recycled crumbed rubber from old tyres with composite fibres in a cementitious
mix design. During the tests, the sprayed Protectiflex walls were hit with shock loadings similar to a car bomb explosion from a distance of 20 metres. Image: Tyre Stewardship Australia

In the past, Protectiflex walls have been used in either cast-in-place or precast construction methods.

The spray on product provides another construction method to the technology making it more cost and time effective, especially when integrating with other construction materials.

The spray-on application can be applied to both new and existing walls and buildings to develop or enhance their blast, ballistic and fire-resistance ratings.

“We are confident these tests will prove the spray-on composite creates blast resistant walls,” he said.

“The ProtectiFlex blast tests will demonstrate how spray-on retrofit could add strength and stiffness to concrete masonry walls, protecting occupants behind it from the blast loads.

ProtectiFlex can be applied across a range of sectors including defence, government, critical infrastructure, petrochemical and retail.

The product has undergone rigorous testing and has achieved the highest levels of protection accreditation in areas of blast testing simulating car bomb and hand-carried explosives, weapon effects testing from an extensive range of projectiles at the highest level of international ballistic rating testing, and two-hour fire and flame testing.

“ProtectiFlex is not only a great way to protect human life and critical assets, it’s also lightweight, eco- friendly, cost-effective and incredibly versatile in its form and application,” Bullock said.

“Although today’s experiment involves testing how the spray-on product handles blasts, we hope to conduct further studies in the future proving it performs just as well in fire, ballistic and weapons tests,” he said.

Tyre Stewardship Australia (TSA) is a keen supporter of Protectiflex and provides support for similar organisations.

TSA CEO Lina Goodmans said the product was a “fantastic use” of end-of-life tyres.

“This innovative product made from recycled tyres could potentially save lives,” she said.

“Although more than half of Australia’s old tyres are recycled, upcycled or processed to make other products, like ProtectiFlex.

Each year in Australia, about 56 million tyres go to waste, and roughly 40 million are recovered or refused from that number.

“Protectiflex is such an innovative product. If it is used in Australia, it is going to protect people in buildings,” Goodman said.

“We want them to be incredibly successful in the market, if they’re successful, it means more waste tyres are being used in applications that are really innovative.”

TSA is a voluntary product stewardship scheme that helps the industry find new markets for waste tyres.

Goodman believed it was the organisation’s responsibility is to help Australia consume more waste tyres.

“We want to see projects like Protectiflex really ramp up,” she said.

“We really want to make sure waste tyres are not causing environmental and social harm and lots of new markets are being developed in Australia for this waste product.

“We really want to be the custodians of our own waste.”

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