Plastic binder

RESOURCE EFFICIENCY FOR AUSTRALIA

ROAD MAINTENANCE HAS CREATED ITS FIRST CRUMB RUBBER BITUMEN BLEND CONTAINING RECYCLED PLASTICS AS THE COMPANY LOOKS TO PLAY ITS PART IN PRODUCING SUSTAINABLE RESOURCES. I n 2019, the Council of Australian Governments set out a timeline which will see the export of recycled plastics banned from Australia. This announcement inspired the construction industry to look at avenues to incorporate more recycled plastics into its work.

Prior to that, the Victorian Government had also introduced a Social Procurement Framework, including three sustainability objectives for procurement on government projects.

Any contracts over $50 million dollars for the Victorian Government must include targets and contractual requirements based on this framework, which is another factor pushing the Victorian construction industry to pursue sustainable alternatives such as recycled plastics.

These incentives have seen many asphalt manufacturers around the country trial and demonstrate well-performing mixes containing different plastic products such as milk and shampoo bottles.

However, using recycled plastics in bitumous binder blends has not been as widely trialled and tested so far.

In an attempt to contribute to the industry’s increased sustainability effort, Road Maintenance has successfully homogenised roadside recycled plastic and crumb rubber into a bitumen binder blend.

The Australian owned and operated asphalt binder manufacturer has now created a new mix using household recycled plastics and recycled crumb rubber from truck tyres together in a bitumen blend.

Road Maintenance has long been using crumb rubber bitumen blends as a binder, crack sealant and spray seal.

The company’s owner, Max Fitzgerald, says following extensive research, it has created a binder using recycled plastic with no microparticles.

In 2019, Austroads released a report called ‘The benefits and challenges of using recycled plastics in asphalt and sprayed seals’. Its author Christina Chin stated some of the concerns found in the report centred around health and safety.

“Another major concern is microplastics leaching out from our pavements into waterways, posing a serious threat to our marine life,” Ms. Chin said in a media statement.

Mr. Fitzgerald said it took a considerable amount of testing to make a binder containing waste plastic that doesn’t damage the pavements’ sustainability.

For the new plastic binder, Mr. Fitzgerald says he decided to homogenise the binder in an effort to stop microparticles leaching out from the binder during the pavement’s life.

“The new binder can be used in existing asphalt plants and spray seal units with no special equipment needed. This is with over 20 per cent crumb rubber and over two per cent recycled plastic,” he says.

Mr. Fitzgerald says the company used high percentages of crumb rubber in the mix to counter the rigid waste plastic and increase sustainability.

“I hope that this will allow the use of waste plastic in pavements without future problems,” he says.

Road Maintenance has been blending crumb rubber for over 40 years. In recent years, the company has been successful in eliminating the odour of crumb rubber modified binders.

Mr. Fitzgerald is excited to begin using the company’s newest developed binder with recycled plastic across the country.

“This blend fits into current specifications for asphalt, crack sealing and spray sealing. This new binder doesn’t contain microplastic which might leak into waterways as the pavement deteriorates over time, so it is perfect for a wide range of uses,” he says.

This binder can also be used with other environmentally friendly road construction initiatives such as reclaimed asphalt pavement (RAP) or asphalt Test results for the new binder both with more than 20 per cent crumb rubber and more than two per cent waste plastic. Polymer modified binder test report for asphalt Test type Test method Results Ring and ball method softening point (Celsius) AG:PT/T131 75.6 Viscosity at 160 degrees Celsius AG:PT/T111 5.96 Torsional recovery, 30 seconds at 25 degrees Celsius AG:PT/T122 54 Polymer modified binder test report for spray sealing Test type Test method Results Ring and ball method softening point (Celsius) AG:PT/T131 62.7 Torsional recovery, 30 seconds at 25 degrees Celsius AG:PT/T122 47 Viscosity at 160 degrees Celsius AG:PT/T111 3.9 Segregation value (per cent) AG:PT/T108 4 Flash point (Celsius) AS2341.14 339

An example of cold joint asphalt that Mr. Fitzgerald says has not bonded well.

containing recycled glass.

However, Mr. Fitzgerald warns when using RAP, the material should be well tested before it’s used so that it complies with conditions for the Southern Hemisphere.

Mr. Fitzgerald also says the new binder reduces bitumen content by 25 per cent when compared with some of his previous mixes.

“This can help with reducing bitumen

An example of moisture seeping through the pavement into the subgrade.

imports into Australia because we are replacing some of the bitumen with crumb rubber and plastics which would otherwise have turned into waste.”

Crumb rubber bitumen blends have many benefits, including ensuring the pavement lasts longer.

The company’s original VRMB blend made with 20 per cent rubber can be used on both open graded and stone mastic asphalt mixes.

Mr. Fitzgerald says the company has blended 9000 tonnes of asphalt for the City of Casey and City of Cardinia in Victoria. Road Maintenance has also supplied its binder to the City of Mitcham, South Australia.

He says this blend was found to be non-porous to water which can extend a pavement’s life.

“It is important for a sealant to be nonporous to water because if water settles in the pavement, it creates a weaker surface and when traffic runs over it, the pavement can break down.”

Mr. Fitzgerald also says curing a crumb rubber binder can improve skid resistance, reduce pavement thickness and reduce tyre noise from traveling vehicles.

“The original crumb rubber VRMB blend has a high torsional recovery result, which shows the blend resists rutting and can withstand heavy and high traffic loads while performing well over a long life,” he says.

“This and the new plastic binder will hopefully play a part in improving the construction industry’s effort to be more sustainable and have a positive impact on the Earth’s ecosystem.”

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