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The PlastiPhalt surfacing at Christchurch Airport includes about 3000 old oil containers, which were chipped down and then melted into the glue component of asphalt to replace virgin polymers – Photo courtesy of Christchurch Airport

Used materials finding roading reuses – the rise of plastic pavements – By Iain MacIntyre

Promising initiatives to recycle plastic and other materials within road surfacing compounds are on the increase in New Zealand and across the Tasman, as appreciation grows that environmental solutions need to be found to address such issues as mounting plastic waste.

As reported in the June-July’19 edition of NZCN, the New Plymouth District Council (NPDC), in partnership with EnviroNZ, Road Science and Downer, recently commenced a trial of the newly developed Plas Mix surfacing on part of New Plymouth’s Liardet Street.

With plastics collected from roadside recycling within the district included in the mix, the asphalt is being tested on a section of the road that is 90 m long (covering a 1255 cu m area), explains NPDC infrastructure manager David Langford.

Downer partnered with the City of Adelaide to construct new pavement on Chatham Street in the city’s southwest – the asphalt is made completely from reclaimed pavement from local streets and recycled vegetable oil from local suppliers – Photo courtesy of Downer Australia

“Here at NPDC, we’re on a journey to attaining zero waste and this could be a game-changer in terms of how we recycle plastics that are difficult to dispose of. Anything that can help cut down on what goes to landfill and boosts reusing and recycling is good news,” he tells NZCN.

“It’s too early to say how it’s working though, as we want to give it a decent amount of time and traffic use before we determine its performance. We’re expecting to do this in the New Year.”

If successful, then in addition to serving as a means of recycling plastic, Plas Mix will also help reduce the amount of bitumen used in resurfacing roads, adds Mr Langford. “We also want to continue to work with Road Science to see if we can increase the amount of plastic we put in the asphalt.”

Christchurch Airport trial

In addition to the NPDC trial – which is understood to be the first time household recycling has been used on a public road in New Zealand – the commercial viability of Fulton Hogan’s PlastiPhalt® surfacing is being proven in a trial at Christchurch Airport.

Following four years of research and development, Fulton Hogan laid 250 tonnes of PlastiPhalt at the airport’s fire station in 2018, where it is accommodating fire engines weighing up to 60 tonnes.

Christchurch Airport sustainability and strategy general manager Rhys Boswell says the airport’s PlastiPhalt surfacing includes about 3000 old oil containers, which had been chipped down and then melted into the glue component of asphalt to replace virgin polymers.

“It’s great that they have been diverted from landfill,” he says. “This product offers some really exciting technology which, as it evolves, will enable us to put old plastic to good use. The team at the airport are delighted to be part of it.”

Understood to last about 15 years, after which it can be milled and recycled again, the PlastiPhalt surface has to date performed to both partners’ expectations, adds Fulton Hogan national products manager Clare Dring. “Given that PlastiPhalt is designed for heavy load areas, these expectations were quite high in the first place, and that’s why the paving was done around the fire safety area,” she says.

“The interest by Christchurch Airport has led to much wider interest among other public and private organisations, in part due to the fact the airport is well known for its sustainability initiatives.”

Auckland Airport deployment

Following the positive reaction to Christchurch Airport’s deployment, Auckland International Airport commissioned Fulton Hogan to lay about 2.1 ha of its taxiways with PlastiPhalt. Containing the equivalent of 31,311 five-litre oil containers, this is New Zealand’s largest project using asphalt made with recycled plastic, according to a company brochure.

‘Auckland International Airport was seeking an asphalt capable of carrying the loads of their heaviest aircraft – Fulton Hogan’s laboratory, design and manufacturing teams combined to complete designs of PlastiPhalt AC20 and AC14 for the taxiway repairs,’ it states.

Part of New Plymouth’s Liardet Street has been laid with the newly developed Plas Mix surfacing – the trial is ongoing, with results of its performance expected in the New Year – Photo courtesy of New Plymouth District Council

‘The team paved almost 600 tonnes per day – a total of 5880 tonnes within the required 10 days, running 24 hours and involving all Fulton Hogan’s supply chain – laboratory, milling, paving, transport, sealing, RAP [recycled asphalt production] plant, asphalt plant, polymer plant and line marking. Given the live nature of the Auckland International Airport site, it’s also been a chance to test the ability to lay this new surface in challenging timeframes.’

Clare Dring adds that discussions are continuing with different parties over future potential deployments. “Much of the timing for a PlastiPhalt delivery reflects contracts where the allowance for a product like this is suitable,” she says. “We can produce PlastiPhalt at considerably higher levels. The ultimate level will be determined by demand.”

Across the Tasman

Among examples of similar initiatives across the Tasman, about 200,000 plastic bags and packaging, as well as 63,000 glass bottle equivalents, were used within 250 tonnes of asphalt laid on a 300 m stretch of Rayfield Avenue in Melbourne’s Craigieburn in 2018. The trial project – involving Hume City Council, Downer and resource recovery and recycling companies Close the Loop and RED Group – also included toner from over 4500 used printer cartridges and 50 tonnes of recycled asphalt.

Comments Downer road services executive general manager Dante Cremasco: “What is also pleasing to see is that this sustainable, cost-competitive road has a 65% improvement in fatigue life and a superior resistance to deformation, making the road last longer and allowing it to better handle heavy vehicle traffic.”

Downer also recently partnered with the City of Adelaide to surface Chatham Street with completely recycled material consisting of reclaimed asphalt pavement from local streets and used vegetable oil from local suppliers. Lord Mayor of Adelaide Sandy Verschoor says the achievement aligns with the council’s ambitions to become a leading smart, green, liveable and creative city.

“The project originates from a motion on notice brought to council last year, which asked the administration to seek to maximise the amount of recycled material used within our roads,” says Ms Verschoor. “At around the same cost as the standard process, the recycled road is cost-effective and, as we’re recycling our own materials, it has a great benefit to the environment.”

It is understood that a handful of councils across three Australian states have in recent times formed such partnerships to surface small roads using recycled materials. These initiatives will undoubtedly be boosted by the Australian government’s recent commitment to working with its states to establish a timetable to ban the export of waste plastic, paper, glass and tyres.

Iain MacIntyre is an award-winning journalist who specialises in transport and infrastructure issues within New Zealand
I.macintyre@xtra.co.nz

 


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