The use of plastics in roadbuilding is growing internationally and has shown it can enhance asphalt mixes, adding both strength and longevity, but in B.C. it is at best a toe-hold on providing better roads.
“Our industry is a bit of a dinosaur,” said Todd Strynadka, technical services manager with Terus Construction, a road construction group that operates in British Columbia and the Yukon.
Strynadka is also past-president of the Canadian Technical Asphalt Association (CTAA), an organization dedicated to the technical merits of asphalt and paving.
“The industry waits to see what happens in 20 years before it makes a change,” he said.
Strynadka believes there is an upswing in polymer use in asphalt mixes which will continue to grow.
“Where a long-term guarantee is needed, we are adding polymers,” he said.
These are mainly private jobs such as mill sites or areas where asphalt will see heavy traffic or loads.
Plastics range from simple polymers to more complex “blue box” waste plastics.
“There is more and more use of polymers but mainly on specialty projects,” said Jason Herring, technical adviser for BA Blacktop and the B.C. director for the CTAA.
Polymers are an additive binder to asphalt’s aggregate and bitumen and are known to extend the upper and lower temperature thresholds because of its elasticity.
Herring said polymer asphalt had recently been used on projects such as a Vancouver International Airport runway and specialty work like the South Fraser Perimeter Road which used polymer-modified open-grade friction course pavement, allowing surface water to flow through it.
Green-way or green-wash?
More challenging are the complex plastics that are found in a range of products ranging from water bottles to carpet. In 2012, the City of Vancouver showed off a pilot project on the Kingsway that used recycled blue-box plastics mixed into the asphalt.
The event, covered by a stream of media, had project engineer Peter Judd (now retired) in a CBC clip claiming one per cent of recycled plastic was used in the mix and the lower melting point resulted in a warm asphalt mix (WAM) thereby reducing energy needs by 20 per cent and emissions by 30 per cent. Approximately 400 kilograms of waste plastic recycled into pellets were shipped to B.C. by producer GreenMantra Technologies from Ontario.
Karyn Magnusson, now deputy city engineer with North Vancouver, was with Vancouver when the pilot occurred.
“It was really our intention to prove out the technology,” she said.
The application was along sections of the Kingsway, an arterial road that is high traffic and a busy bus route. An attractive feature was the converted pellet wax material could be used in a WAM rather than a hot asphalt mix.
The pilot was considered the first in Canada. But, following the project’s conclusion, virtually nothing has been written on how well the project has held up.
Magnusson said she had driven to the area recently and the paving looked to be standing up well. She said Jeff Markovic, currently manager of Vancouver’s Kent Construction Supplies and Services, the city’s asphalt plant, was one of the pilot leaders.
The Journal of Commerce attempted from May 16 to May 24 to speak to someone from the City of Vancouver engineering department to discuss the pilot project, but no one from the city had called back by deadline.
A 2016 report by UBC student Sydnie Koch entitled Improving Sustainability Practices by Repurposing City Construction Waste points out the city’s Kent asphalt plant and production facility is unable to utilize 100,000 tonnes of road waste annually and is limited to a 25 per cent RAP (recycled asphalt pavement) content because of plant emission limitations and feeder equipment that limits production. The report makes no mention of recycled plastics.
Herring said it would be interesting to see a paper presented at the CTAA on the section of Kingsway paved using the recycled plastic, however, he is not aware of any study done on the project and the city does its own self-performance evaluations.
Domenic Di Mondo, one of GreenMantra’s earliest members, remembers when Vancouver came knocking on its door with the proposal of using recycled plastics, which his company was pioneering in Canada.
“They wanted to be the greenest city in the world by 2020 and put together a variety of different initiatives,” he said, adding roadbuilding was one. “They had heard of GreenMantra technology and reached out to us.”
GreenMantra is known for taking many of the discarded plastic items ranging from plastic bags through to carpeting and turning them into a wax pellet that can be used as a binder in materials including asphalt.
“Things such as milk jugs, grocery bags, containers and carpet are all feed stock,” he said. “These are everyday items that would otherwise go to landfill.”
The process is not as easy as it sounds as each plastic product is made using a different formula. The grades are marked on the bottom of the items (usually with a number) which designates the formula used to make the item and helps organizations like GreenMantra break down the item into a wax-like pellet.
“We handle No. 2, No. 4. and No. 5 items and will be doing No.6,” he said.
Di Mondo said after the Vancouver project, the company’s product went mainly into roofing asphalt which grew at a faster rate than the paving side.
He said now that the company had developed the roofing side of the business, there was the intent to again further pursue the paving business.
Europe racing ahead
While Canada is just edging into the use of more complex plastics, Europe and other parts of the world are racing ahead.
The difference is in the design perception; Europe looks forward at what can be while Canada looks back at what was, Strynadka stated.
“In Europe, they absolutely design the road to the performance standard of the materials and the overall design of the road they want,” Strynadka said. “We are using an empirical design method and using what worked on roads in the last 20 years.”
Emergent Scottish company MacRebur has developed technology that reduces waste plastic into a form that can be mixed with asphalt. The three additives are: MR6, MR8 and MR10. MR6 is designed to increase strength and retain asphalt shape in slow lanes or at bus stops and is effective in hot climates, while MR10 increases flexibility and resistance in colder climates. MR8 was designed as a bitumen replacement as concerns rise about bitumen.
The MacRebur product has been used in the U.K. with councils in Enfield, Cumbria, Dumfries and Galloway and Northumbria. MacRebur, in press coverage, claimed it had upcoming trials in Bahrain, Abu Dhabi, Saudi Arabia, the U.S. and Canada.
The bitumen replacement is a concern as countries see future shortages and rising costs. On Jan. 1, 2020, the International Maritime Organization will have new rules in effect which limits fuel sulphur to half a per cent, forcing companies to upgrade their technologies leading to lighter crude oil feedstock that does not lend itself to bitumen production.
India is the acknowledged leader; it put down its first waste plastic road in 2002 mainly through the work of two brothers K. Ahmed and Rasool Khan who set up KK Plastic Waste Management in Bangalore. India has also published a code for the hot and cold mixing of plastic waste at plants. Since its first road, according to World Highways Magazine, KK Plastic’s product has been used on 3,000 kilometres of Bangalore road with its KK Poly Blend mixed at a rate of eight per cent to bitumen.
Other authorities in India are now following suit and using plastic waste additives.
Plastic road sections
A Netherland company has gone completely plastic; KWS, part of the VolkerWessels group, has devised PlasticRoad, which consists of staple-shaped arch sections that are prefabricated and placed onsite. The sections have hollow interiors which allow for easy access to infrastructure. A trial project, a bicycle lane, is planned in 2018 with the company claiming they last three times longer than asphalt roads and are low maintenance.
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