Four SAIT students say they may have found a solution to Calgary's damage-prone sidewalks

A group of civil engineering technology students at the Southern Alberta Institute of Technology say they're well on their way to finding a solution to Calgary's perpetually cracking sidewalks, caused in part by the city's notorious freeze-thaw cycles.

The students say plenty of research has been conducted into how graphene — a carbon-based, ultra-thin material that's stronger than steel — makes concrete more durable and more water resistant.

So when they started to explore how the substance could improve infrastructure in Calgary, and potentially save some costs, they landed on sidewalks as their focus.

"We want to be able to make something that could basically benefit the community," said project lead Derrick Leung, who worked alongside Tony Ly, Pinyo Sirisettanan and Chi Kin Wong.

Over the course of six months, the group added graphene to concrete, poured sidewalk-sized slabs, and conducted many compressive and freeze-thaw tests to see if their theories held up.  

In the end, they were able to confirm their suspicions. 

"We were able to prove that, yes, indeed, by adding a certain amount of graphene you can get an increase in strength," said Leung. 

"We were also able to prove that the addition of graphene has higher resistance than regular concrete, based on these different theories of water impermeability."

That's especially important in Calgary, where temperatures can fluctuate significantly day-to-day, causing concrete to expand and break, added Leung.

Saving costs, reducing emissions

The students are now aiming to save the city costs and reduce greenhouse gas emissions with their innovation.

According to Leung, in 2023, the city spent $8 million on sidewalk repairs alone.

"If we can increase the strength of concrete for sidewalks, potentially we can reduce the amount of cement that's being used in these concrete mixtures ... [that] could lead to a reduction in maintenance costs, can potentially lead to a longer operation lifespan, as well as stronger freeze-thaw resistance," said Leung.

Limiting the amount of cement used to make the city's concrete could help with a larger, more difficult goal: reducing Calgary's greenhouse gas emissions to 60 per cent below 2005 levels by 2030.

Cement is the world's second-largest CO2 emitter and is responsible for about 1.4 per cent of Canada's carbon emissions.

"Over time, assuming that there's going to be a longer lifespan, you have a reduction in CO2, you're going to potentially use less concrete over time, less maintenance, less repairs," said Leung.

"We could reach those net zero goals a lot faster and have the funds allocated for the sidewalks and pathways … to help benefit the rest of the city."

While there is more work to be done, Leung said two other capstone groups have agreed to take over the project when the current students graduate next month.

Working with the city

Rick Duchscher, with the Southern Alberta Institute of Technology (SAIT), has helped connect the four students with industry contacts and other groups — like Chandos Construction, SAIT's concrete lab, and carpentry students — to help move the project along.

The team's concrete slabs are currently in storage at SAIT's Connector Lab, which acts as a library for specialized technology.

"It's kind of a showcase project in that there's many unknowns, the group is trying something that hasn't been tried before, we've implemented a lot of different phases in this project that go past just the design phase," said Duchscher.

"This project, we hope, will be adopted by the City of Calgary to include more investigations by future groups and more additional testing in the upcoming year."

According to an emailed statement from Chris McGeachy with the City of Calgary, the city has provided expertise to the students in how their innovations can be applied in practical situations within Calgary's communities.

"At this time, however, the work exists solely at SAIT. The City looks forward to continuing its work with these students to assess if their results can be applied in our neighbourhoods, beyond the lab stage."

McGeachy said in recent years, the city has increased the use of low carbon cement to reduce its carbon footprint.