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Paving the way with toner waste

Companies who want to know how they can help with the circular economy in terms of reusing, repurposing, recycling and reducing their waste footprint, should look to the collaboration between Close the Loop, Downer and CPB Contractors. The trio has come together to turn plastic powder from toner cartridges and waste soft plastics into a valued commodity.

It hasn’t been an easy road. The final product – TonerPlas, which is used in road construction – took Downer and Close the Loop (CtL) the best part of 10 years to realise. But it’s been worth it.

Toner cartridges and its residue powder had been destined for landfill as there didn’t seem to be any way they could be recycled into anything useful.

However, when Downer and CtL joined forces they discovered by adding soft plastics to asphalt, you get a product that ticks several boxes on the road construction front, and thus TonerPlas was born.

“It’s great at increasing stiffness and increasing the service life of an asphalt road,” said CtL’s founder Steve Morriss. “We started years ago by surveying some roads that had been laid that included toner powder as an additive in Texas in the US.

“That project was abandoned because of safety and health issues, but I had three different sections of that road surveyed and realised that it was adding significant value to reduce cracking and rutting in asphalt.

“Fast forward a few years and we had partnered with Downer by this stage. We started to think ‘how could we make the asphalt additive more elastic?’ That is when we moved to the mixed soft plastics and the REDcycle program.

“We are now the largest user of this particular waste stream from all Coles and Woolworths stores throughout Australia.”

At its most basic, TonerPlas is a polymer. Graham Henderson, who is the manager of precontracts and development at Downer, said the journey to getting the new material in asphalt started a while ago with another CtL product, which was
used with an additive that Downer
had developed.

“CtL first created a product called TonerPave, which was predominantly a toner-based additive that had some performance-enhancing characteristics about it,” said Henderson.

“Through the journey with them we started talking about ‘what’s next in asphalt?’ and looked for something new that would help solve the problems around waste.

“It was the same for all of our customers when it came to waste plastics that generally didn’t have any recycling avenues.

“CtL went off and did some research. We had input on what an additive needed to be working with our asphalt plant, and what sort of form the additive would need to be to get
into our mixes. After a collaborative journey of a couple of years, we developed the product.”

So where is TonerPlas being used? Raphael Touzel is a project director for CPB Contractors, a company that specialises in infrastructure projects including roads. It too was looking for sustainable products to be used as an additive to asphalt on some of its projects, including an upgrade on the M80 Ring Road in Melbourne, Victoria.

The company works closely with Victoria’s Department of Transportation (DOT), a state government entity that has stringent rules on what it allows in its roading aggregate.

“The DOT is really strict with their pavement designs,” said Touzel. “They own the pavement design, which is pretty robust, and they want it to last for a number of years for future increased traffic loadings. Once you build a new pavement, and you’ve got traffic running on it – especially a freeway – you don’t want to be going back to improve it. They’ve got a design that is fairly conservative and that is what we had to work with.”

What are some of the properties of TonerPlas that make it suitable for roading? According to Morriss it has improved resistance to rutting, and improved fatigue life, making it longer lasting with a lower carbon footprint. This has been independently tested by the Australian Road Research Board (ARRB), which is how the company got it approved for use by the Victorian DOT on the M80 Ring Road.

Tests carried out by the ARRB show that under the wheel tracking test – the Victorian DOT standard for this particular mix design has to be less than 11mm – the TonerPlas version came in at 2mm and the baseline standard asphalt was 9mm.

“We’re talking significant improvements [in fatigue life],” said Morriss.

“What that means is it increases the longevity of the asset. That correlates to about 15 per cent improvement of the life of the road, which in turn correlates to about a 15 per cent improvement in whole of life cost of the asset. It is a low-carbon option.

“If you spread the carbon footprint over 23 years instead of 20 years, you have a significant improvement in the impact of that road.”

The sorting of the waste is key to making sure it meets the specifications to be used.

“We do a manual sort/decontamination,” said Morriss. “We shred the mixed soft plastics then put it through automated cleaning systems, such as rare earth magnets, eddy current separators, and air density separators. They then go into a series of sophisticated mixing machines. These mixers are compounding the plastics and homogenising these plastics into a dough.

“This is where we add the toner powder. Out comes the product, which are small pellets. They end up in bulk bags and can be added as a dry mix additive at an asphalt plant.”

“We’ve done a lot of testing on it in terms of its wear capabilities,” said Henderson. “We had to in order for it to get acceptance from road authorities around the country. We’ve done a lot of performance testing. Our philosophy is that the product has to perform at least as well, and ultimately better, than the standard product.”

As well as meeting the standards of the Victorian DOT, it had to meet the standards set out by the state’s Environment Protection Authority (EPA). This was because there could have been issues with microplastics being put into the atmosphere as the road wears.

“We knew the way that we developed it, and how we incorporated it into the mix that we wouldn’t have a microplastics problem in our end asphalt product,” said Henderson.

“It was very pleasing to have gone through rigorous testing with designing it, in conjunction with the NSW EPA, because they had the most stringent requirements to get it through. That was a process of almost 18 months; sending samples over to Europe. It was a great thing to go through and get the validation at the time. It proved we didn’t have a microplastic issue compared to any other standard asphalt in the market.”

For Touzel, the M80 project has always been about using recycled pavement materials.   

“When you demolish buildings, bridges, pavements or other concrete structures, it gets crushed up and turned into a road base instead of going into a landfill,” he said.

“All our pavements we have built are built out of recycled products – brick, concrete, old road base, recycled glass.

“It used to be that virgin aggregates would be needed, which would come out of different quarries to meet specification. Now it’s all recycled and blended mixes which can still meet the requirements.”

Then there is the asphalt layer, which is where TonerPlas comes into play.

“Downer’s tech expertise mixed with Steve’s knowledge got this across the line on our project,” said Touzel.

“It also helps to have a client who has a recycle-first policy. We believe in a recycle-first narrative, so we brought all that stuff together and thought ‘let’s give it a go’.”

However, is there enough toner powder and cartridges to continue making TonerPlas to do the job?

With a lot of companies going paperless, or at least vastly reducing their printing needs, will there be enough product available in the future? Morriss is confident there will be. Even if there isn’t, he’s not panicking about finding another source.

“There is scope to increase the amount we can produce,” he said. “We are never going to run out of toner powder. If we ever did in Australia, then we can call on the toner powder from our US or European business as a resource. It is a polymer. There are many sources of waste polymer that meet our spec.”