Hemp makes concrete stronger

A hemp bale waits to be processed at Canadian Greenfield’s decortication plant in Calgary.  |  Canadian Greenfield photo

It is the classic case of a problem in need of a solution.

For decades, the concrete industry has relied upon steel, glass and plastic fibres to reinforce concrete. But those materials aren’t great at preventing cracking in concrete. Shortly after pouring, tiny cracks can form in concrete and those fissures eventually become much larger cracks.

Enter Mike Pildysh.

About six years ago, Pildysh, a concrete expert and registered engineer in Ontario, British Columbia and Alberta, set up a company in Calgary called Canadian Greenfield Technologies. The company had one major goal — develop reinforcement products that could mitigate concrete shrinkage cracking, according to a report that appeared this summer in constructconnect.com, a company that provides data to the construction industry.

After considering options, Pildysh and his team selected the fibre from industrial hemp plants.

“We tested a bunch … and the highest tensile strength was hemp,” said Stephen Christensen, vice-president and general manager for Canadian Greenfield Technologies.

Their research showed that hemp fibres reduced cracking and outperformed existing technologies. But there was one large problem: the hemp fibre on the market didn’t meet their needs.

Two types of fibre are found in hemp stalks — bast and hurd. Bast fibres are longer and more valuable than the short hurd fibres.

The bast from traditional hemp decortication plants wasn’t up to snuff for concrete reinforcement because it took multiple cleaning processes to get the hurd out of the bast, said Christensen, who has a PhD in chemistry.

“Our (experience) was in the concrete industry,” he said. “Coming) from the concrete industry, we had no drive (or reason) to enter hemp.”

However, after identifying hemp as the best choice for reinforcing concrete, Christensen and other scientists with Canadian Greenfield had to become experts in processing hemp fibres.

Eventually, they came up with a new process.

“After extensive research … (Canadian Greenfield Technologies) has developed and implemented the HempTrain decorticator technology,” the company said in news release. “The cost of a HempTrain decortication facility is much lower per ton/hour of throughput than conventional decortication technologies, while producing much higher value.”

Canadian Greenfield has been operating its decortication plant in Calgary since 2016. But it is now ready to sell the technology to other players in North America’s hemp industry.

“It is a full-on facility people can buy,” Christensen said. “And we’ll ship it out to them and they’ll be able to get in business, making whatever they want in fibre, hurd, microfibre or both.”

The HempTrain technology is different from hammer milling, the traditional method of separating hemp fibres.

Christensen described a hammer mill as putting hemp stalks on a screen, then beating the stalks with a hammer until the smaller hurd fibres fall through the screen.

The beating can damage the bast fibres, making them unsuitable for concrete reinforcement.

“(HempTrain) works to get a cleaner fibre that is longer and coarser and stronger,” he said.

Hemp fibre from the Canadian Greenfield plant has been used to build skateboard parks across Canada. It was also used in Beijing to construct the bobsled and luge tracks for the 2022 Winter Olympics.

Canadian Greenfield’s hemp fibres can be used in standard concrete, decorative concrete (which contains fewer aggregates) and shotcrete, where concrete is sprayed through a hose.

The market for smooth, crack-free concrete is huge and global, but Canadian Greenfield has also developed other products.

The company is using its hemp decortication plant to make things like kitty litter and soil enhancers.

“About 60 percent of the bale (is) hurd,” Christensen said. “You have to develop some products otherwise you’re just drowning in it. That’s where our garden line and our cat litter … came from.”

The processing technology also produces a “green microfibre stream, rich in CBD”, the company’s website says. CBD, or cannabidiol, is a compound found in the plant tissues of industrial hemp plants. Studies suggest it provides pain relief and has anti-inflammatory properties.

After decades of prohibition in America, about 20 U.S. states now permit the production of hemp for research purposes and federal legislation has been introduced to make it fully legal.

A number of American entrepreneurs are interested in the HempTrain technology and they will travel to Canada this fall to have a look at the decortication plant in Calgary.

“We’re setting up tours for September,” Christensen said.

“We were going to two weeks (of tours) and now it’s going to three…. People really want decortication and there is nothing out there that isn’t steel hammer mills.”

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