Asphalt mixes: You get what you pave for

Dr Simon Hesp, an engineer in the department of chemistry at Queen’s University in Kingston, is promoting the use of better asphalt on Ontario highways.

Speaking to Timmins council,  Ontario, Canada this week, Hesp said part of the solution involves removing recycled additives, such as motor oil, from asphalt mixtures.

Hesp said his research in the past 15 years with the  Ontario Ministry of Transportation has been trying to find better asphalt cement and materials that last longer than the average. He said the “average” quality of asphalt cement has decreased in the last 25 years.

“Basically, we have investigated numerous pavement failures around Ontario. Premature cracking is an unfortunate fact of the industry today,” Hesp told council.

“We have looked at pavements in the North originally and we are starting to see much more distress in large urban areas like Toronto, southwestern Ontario, Kingston and everywhere else. It has now spreading pretty much everywhere.”

Hesp said the  Ontario Ministry of Transportation has supported several control trials for different types of pavement, asphalt and additives to the asphalt, including trials in Timmins.

“I have been involved in the last four of those. I have designed those and the ministry has tendered them and the contractors have built them, two of which are on Highway 655 north of here,” said Hesp.

He said one test site is just north of the railway tracks near the Kidd Mine road, while the other test site is further north, closer to Highway 11.

“We have 15 different test sections for different compositions and they perform vastly different,” he said.

For comparison, Hesp showed a video of a section of road in Eastern Ontario near Highway 138 near Cornwall. One section of road showed a section of asphalt about 10 years old that Hesp said “looks pretty good” with very little distress. Just down the highway, however, there was another section of asphalt, 12 years old, that was severely cracked in several areas. He said the issue was the use of unwanted additives in one batch of asphalt.

“The ministry sealed about 66 kilometres of cracks in the first five years. You can see the sealing didn’t help very much. It just continued to crack in between the seals and this road may have lost about 10 years of a useful life,” said Hesp, adding that instead of 25 years, the road might get a 15-year-life cycle.

“We see this all over the province. Everywhere we see premature failure,” he said.Hesp said the bad highways far outnumber the good highways.

“We see very few good ones. They’re pretty old pavements that have lasted for 20 years, virtually no distress.”

Hesp added that asphalts in the North have to be moisture proof because if the tiniest bit of water seeps down into the pavement, it will freeze and expand, which will lead to premature cracking.
He said the province of Ontario launched a new approach to paving in the late 1990s that saw the use of recycled materials being added to asphalt.

“In 1998, Ontario fully implemented what is called Superpave. That is an acronym for SUperior PERforming PAVEments,” said Hesp. “We have had many, many headaches since then.”
He said the Superpave program uses the dregs of recycled engine oil, gels, waxes and acids. “Recycled engine oil bottoms is the scourge of the industry.”

Hesp said asphalt is created to withstand certain temperature ranges based on geographic location so the pavement can withstand extremes of summer and winter, in different parts of Ontario. He said asphalt produced for Kingston area roads will have a different chemistry for asphalt required for Timmins area road, where the temperature routinely drops to -30 C to – 40 C.

“The cheapest cost additive, the most economical one has proven to be recycled engine oil bottoms,” he said, and added that engine oil contains zinc and molybdenum additives.
“That doesn’t build very good roads,” said Hesp.

Hesp explained that the engine oil elements react poorly to cold weather in that they “sweat out” of the pavement and they are exuded from the asphalt, which creates premature cracking. One of the problems is that asphalt companies keep trying different additives to find the best possible pavement. As strange as it sounds, said Hesp, even pig manure is being considered.

He said the testing process for asphalt needs to be improved and accepted by government so that good additives are accepted and bad additives are weeded out.

The good news is that at least three new types of asphalt are being developed in Ontario and put to the test around Ontario. He said the different asphalts all have different properties. One is considered the best for low temperature applications.

Using slides, Hesp showed one test section of Highway 655 where the asphalt has very little damage while another section is seriously cracked with moisture damage.

Hesp said that in his home community, the City of Kingston, opted for the better grade of asphalt and ordered that no cheap additives be used as a binding agent. He said Kingston is becoming well known for its good roads. Hesp said all asphalt contractors will use the cheapest available materials to get the job done.

Hesp suggested that asphalt tenders should be specific that about using top grade materials. He said contractors can be ordered to use better products. He said the city can take a sample of the asphalt, while the paving job is underway, and put the sample away in storage with the date and contract number.

“If you ban it and force them to disclose with pre-approval then you can be sure that you keep your samples, if the road fails we can investigate, we find it, the contractor will pay rather than the taxpayers of Timmins,” said Hesp.

Hesp said it is not impossible to build roads that will last 20 and 30 years “if you choose the right materials and you leave out the motor oil.”

Hesp said the issue is becoming highly politicized. He mentioned that he published a paper a couple of year ago that prompted legislators in some New England states to launch an immediate ban of motor oil in asphalt.

Hesp said that many of the asphalt mixtures provided in Timmins and across Northeastern Ontario have unwanted additives such as motor oil. He said the buyer can demand that no unwanted additives go into the asphalt. It will take political will.

“You have a political issue in your hands. If you put this in some contracts, you will probably see a price increase. Timmins, I must say, unfortunately is the worst location in Ontario to put this in a contract, but you will get what you ask for but you may have to pay for it more,” Hesp told city council.

“I encourage you to put your foot down and say this is about sustainability. If you’re going to replace Algonquin Boulevard, you don’t want it to look five years later just the same. So do it wisely.”


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