Roads & Paving
Green asphalt: A look at Green Roads Recycling
By Carroll McCormick
B.C. paving company specializes in on-the-spot transformation of old road surfaces.
By Carroll McCormick
October 4, 2016 – The equipment train creeps along as it continuously heats and grinds off 50 millimetres of old asphalt surface. A conveyor passes it back into a twin-shafted pug mill where it is thoroughly mixed with a rejuvenating agent and 20 per cent virgin asphalt. Another conveyor dumps it into a paving hopper. It is laid down and compacted to the correct density. Twenty minutes later, the freshly recycled layer of pavement is ready to drive on.
This is the essence of a 64 lane-kilometre resurfacing project carried out this past spring, between May 9 and June 22 by Fernie, B.C.-based Green Roads Recycling Ltd. The work took place on two sections of highway, one 14-kilometres long, the other 18-kilometres long, a few kilometres east of Kamloops. With this project, Green Roads Recycling has now resurfaced 5,000 lane kilometres of road using hot-in-place asphalt recycling (HIP AR), a method it has used for 27 years.
“We are working with what is already in the road,” says Shane Stothert, general manager for Green Roads Recycling. “Only 20 per cent of the material is new.”
Green Roads Recycling estimates that over 13,000 kilometres of B.C. roads have been repaved using HIP AR.
“You can’t drive anywhere in British Columbia without driving on recycled road,” Stothert says. “We are the only place in the world with contractors bidding competitively in hot-in-place roads. The British Columbia government has been one of the main proponents in adopting this technology.”
The company figures that this amounts to around six million tonnes of recycled asphalt, which adds up to 360,000 tonnes of oil and 5.64 million tonnes of rock and sand that has not been trucked away and downcycled for uses such as surfacing side roads.
“This is not a new technology,” Stothert says. “The original innovator of HIP recycling was RW Blacktop. HIP AR has been in place for 50 years. His father bought RW Blacktop, the innovators of the technique, in 1989. In 2005, Shane changed the name to Green Roads Recycling.”
HIP AP, which is an on-the-spot version of mill and refill road repair, is fast and convenient. For example, Stothert says of this one-step, in-and-out process, “We come along, block off an intersection, and 20 minutes later the restaurant or gas station is reopened. It minimizes retail inconvenience.”
Despite the advantages of HIP AR that Stothert touts, the competition from traditional paving companies is ever-present, and his company must be vigilant about correcting misinformation about the method. For instance, the word “recycling,” clouds some people’s appreciation of the quality of the work.
“We are recycling, so the work is not seen as valuable as regular paving,” Stothert says. Yet, he says, “The specifications are very strict: density, voids, smoothness. The governments are not accommodating us. They are working with us.”
A constant with the company is educating new government people about HIP AR, something that keeps Shane’s brother Jamie busy handling most of the government bureaucratic relations. Their father spends most of his company time maintaining their contacts and connections with the government.
Stothert is very aware of the need to dispel myths about HIP AR – like the claim that the method overheats the asphalt, for example.
“The reality is that the material we lay at the back of the screed is as cool, or cooler, than the traditional paving methods,” he says. “We can lay recycled asphalt at around 100C, out the back – around 40 to 50 degrees lower than conventional paving. “Conventional paving lays the material at 150 degrees, [and] you see some black and blue smoke. We are laying our material at 100 degrees. The white smoke you see is coming from the moisture in the road,” he says.
When they heat the asphalt prior to grinding it off, the temperature in the top one to two millimetres is high, Stothert admits, to drive heat into the lower two inches, which is the depth to which the equipment operator wants to remove the old asphalt. But two or three feet back, the temperature is down.
“It is a fallacy that we are burning the road,” Stothert says.
While not all old asphalt roads are in suitable condition for HIP AR, Green Roads Recycling has resurrected some pretty beat up roads. (It is the Ministry of Transport’s job to select the roads that are suitable for recycling, and other contractors fill and patch any potholes before the Green Roads Recycling train comes along.)
Stothert describes the conditions for one project the company did:
“The centre seam was completely blown out,” he says. “There were patches, potholes. This was one of the most challenging jobs we’ve ever done. There were sections of the road where it was not even two inches deep. Our operator sees that, raises the grinders up so we don’t grind up dirt. A lot of add mix is used to fill the ruts, to raise the road back up to grade and stabilize the crown.”
Discussing this spring’s HIP AR project, Stothert says, “Some sections of the road didn’t have 50 millimetres of asphalt. Our operator needed to pay attention to that and raise the cutting edge above the dirt.”
In the past 27 years, Green Roads Recycling has only had one contract where HIP AR was not appropriate, and that had to do with the previous paving contractor having put cutbacks into the asphalt.
Stothert also recalls a case where sulphur and coke had been put in the asphalt. It caused problems, but the company was still able to recycle some of the asphalt.
“We couldn’t mill that material,” he says. “It was cold-milled off, so we could recycle the bottom. We just bumped up the percentage of the new material to bring the road back up to grade.”
Because of the advantages of HIP AR, including fewer emissions and fewer dump trucks on the road, Stothert would like to see the process more widely adopted.
“There are 160 barrels of oil in a kilometre of road,” he says. “The oil and aggregate has a huge half-life. The material’s value is going up with time; it is an appreciating asset. If it can be milled and filled, we should consider recycling it in place first. We are recycling as we go along. It lasts as long as new material. It is completely baffling that this process is not being done all the time. It makes no sense to me.
“Right now, with the price of oil, our savings is about 20 per cent over regular paving. When oil prices are higher, the savings can be as high as 40 per cent. I don’t need a fancy life cycle cost analysis to tell me we are saving millions of