ScienceJune 14, 2019

Testing New Plymouth’s new yoghurt pottle road


An innovative new roading system is being trialled in New Plymouth that could reduce the amount of plastic sent to landfill. It’s a New Zealand-first, so Tara Ward got up close and personal with the road to see what all the fuss is about.  

The fair city of New Plymouth made the news this week for reasons other than being affectionately called “the nipple of the North Island”. In a New Zealand-first, the New Plymouth District Council announced the trial of a new system that takes plastics from the city’s kerbside recycling collection and mixes it into asphalt to make road resurfacing.

It’s called Plas Mix, and it’s being touted as a breakthrough for reusing waste material that would have otherwise been stockpiled or sent to landfill.



Build it and they will come, pour it and I will drive my Mazda Familia over it. Finding a useful alternative for our pesky waste seemed like big news, and I wanted to bask in the glow of hot bitumen mixed with 500kg of residential plastics. Who’s going to turn down the chance to drive on 90 metres of groundbreaking tarseal created from the equivalent of 83,300 yoghurt pottles? Not me, friends. Not me.

At first glance, the new strip of bitumen at the top of Liardet Street leading to Pukekura Park looks like any other road, though the screams of those yoghurt pottles trapped beneath might tell a different story. I’ve never been so excited to see some fresh road before, but did I add to Earth’s demise by driving round the block seven times just to see what it felt like? Probably. Sorry about that.

Once on the new seal, my car drove with a confidence I’ve only ever dreamed of. It’s usually suspicious of both flat and hilly surfaces, but here, we could have been driving on silk. I’m sure the old clanger even purred, for crying out loud. This was fast becoming the best tiny road trip of my life.

Keen to discover the full sensory experience of Plas Mix, I parked the car and breathed the road in. This is what progress smells like, I told myself, as my nostrils began to burn from that fresh tarseal tang. My six year old daughter was just as excited, and insisted on feeling the road. She pressed her wee face to the ground, and I didn’t stop her. I may have even encouraged her.

We both agreed this was the most beautiful piece of bitumen we’d ever seen.

I took my feelings to Darcy Rogers, Technical Development Manager at Road Science and lover of all things roads. He shared my excitement over this new development, which arose after New Plymouth District Council sought a solution to the growing stockpile of Type 3-7 plastics that had previously been exported to China.

Together with EnviroNZ and Downer, they came up with Plas Mix, a road surfacing created by shredding plastics from the kerbside recycling collection and melting them into the bitumen. It’s a big deal, because not only does the surface use plastics that would have otherwise gone to landfill, lab tests indicate it’s a stronger product than standard asphalt.

Just as well, because I read a Facebook comment from someone who boasted they’d done “rarkeys” on the new surface. Rarkeys, as I live and breathe! I put my concerns to Darcy. How could 83,300 yoghurt pottles withstand such incendiary shenanigans?

photo: Screenshot via NPDC Facebook (no evidence this car was doing rarkeys)

Darcy reassured me they’ll monitor the road closely during the trial period. “The average road lasts probably anywhere from eight to 12 years, so it’s a long turn around to know if it’s absolutely perfect,” Darcy says. “But from the lab testing we’ve done to date, we can see it’s going to be at least as good, but probably better, than a standard asphalt.”

It seems Plas Mix-type solutions are the way of the roading future. Queenstown Airport is incorporating waste printer toner and recycled glass into their carpark tarmac, and Darcy says it’s an ideal way of using products that we can’t recycle domestically. Tests indicate the plastic inside the bitumen won’t leach into the environment, and Darcy reckons the most interesting part of the trial was the positive response from everyone involved.

Life is a highway, and if this trial proves a success, more of our roads could be paved with the ghosts of plastic past. It’s the best news my Mazda Familia’s heard in yonks. Rarkey away, New Plymouth.

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