An international effort to reduce concrete’s carbon footprint

Posted on June 03, 2022

How environmentally friendly is concrete? Less than you might think. Reinforced concrete infrastructure accounts for almost 10% of global CO2 emissions, far ahead of the 2% of CO2 produced by the airline industry. Two Queen’s professors, working with academic collaborators at U of T and the University of Cambridge, are working to change that.

Their work is supported by industry leaders including Arup, Aecon, KPMB Architects, and Lafarge, along with the City of Kingston and the Cement Association of Canada, with funding sources including NSERC and Mitacs.

“If we can reduce the carbon produced in concrete manufacturing by even a fraction, that’s going to have a significant positive benefit,” says Neil Hoult, a Civil Engineering professor at Queen’s Engineering. “Increased urbanization means that the demand for concrete is going up, not down. Our research aims to cut the CO2 emissions generated by concrete production in half, the equivalent of eliminating the airline industry, twice over.”




The project, led by Professor Hoult with Josh Woods at Queen’s, Evan Bentz at the University of Toronto, and John Orr at the Department of Engineering at the University of Cambridge, also integrates a number of industry partners who are invested in making their technology and processes more sustainable.

“Lafarge is excited to participate in a project like this one. It fits perfectly into our net zero roadmap,” says Abdurahman Lotfy, Innovation & Development Manager, Aggregates & Construction Materials at Lafarge, Canada's largest provider of sustainable construction materials.  “The integration of our mix design expertise through our EcoPACT product line with structural engineering advances will allow building designers to achieve a much lower embodied carbon than would be possible otherwise. This models the sort of partnerships we need to advance our sustainable targets.”

“We’ve been participating in an increasing number of low-carbon concrete trials and are looking for ways to integrate low carbon options in our projects,” says Prabh K. Banga, Director, Sustainability at Aecon, a Canadian industry leader in the development and construction of infrastructure.  “We are pleased to provide our expertise on how to integrate low-carbon concrete into the construction industry and provide technical advice and resources to design and construct the low-carbon concrete structure for this research.”

“Strategies to make the use of concrete more sustainable with a lower carbon footprint in the built environment should leverage performance in mix designs like EcoPACT, with innovative approaches to structural geometry,” says Matt Humphries, Associate Principal at engineering, consulting and design firm Arup. “Cement is responsible for significant global greenhouse gas emissions, and Arup is committed to collaborating with Queen’s to share and adapt creative strategies it has developed to implement low-volume concrete solutions in both new construction and sustainable renovation projects.”

To achieve the goals set by Queen’s and its partners, several approaches will be explored. “We will be working on several different approaches to making concrete lower carbon,” Hoult says. “The first is shape optimization, in other words only putting material where we need material, which saves on not only material use but also structure weight. If the structure is lighter, then you need even less material.”

“The second is what’s known as functionally graded concrete. We put concrete with higher strength where we need the strength, then we use lower strength concrete, which also means lower cement concrete, everywhere else. We will be working on software packages that allow for these new techniques to be used in the design, optimizing structures for performance and low environmental impact,” Hoult says.

The bulk of the research will be done in the Queen’s Civil Engineering labs. Moving from the lab to practical applications, however, will take the project into the real world in Kingston. “KPMB and Arup will help design the demonstration structure,” Hoult says. “Aecon and Lafarge will help us build it, and it’s all going to happen at the Kingston Fire and Rescue Training Centre. It’s going to be both actively used by Kingston’s Fire Services as a classroom and as a living lab so that Queen’s and St. Lawrence College students can learn about low-carbon buildings. We’re aiming for a net-zero building philosophy.”

This work is important to Hoult, not only as an engineer but as an informed global citizen. “I think the thing that we have going for us is that everyone recognizes that this work is critical for the future of not just the civil infrastructure industry but also the planet.”

“I have been really impressed by how motivated all our partners are to see this happen, devoting considerable time and financial resources to tackling one of the grand challenges of our industry.”

“Kingston is truly a city where history and innovation thrive. The city’s Facilities Management & Construction Services department has been supporting a number of ‘learning hubs’ with post-secondary educational partners; we are working with the low carbon concrete research team to develop a real-world application for demonstration purposes and ongoing research, as well as being an active facility for the city,” says Speros Kanellos, Director, Facilities Management, and Construction.

“Making this low carbon structure net-zero as it relates to ongoing operation and use is pushing the envelope,” Kanellos continues. “It’s really exciting to participate as a partner in the kind of initiative that embodies the city’s leadership on climate action. This work will be so important as we continue to look for new approaches and technologies to aggressively decarbonize our infrastructure.”



 Master's student Jared Mason examines a novel concrete form developed in Dr. Hoult's lab.


 Students examine the properties of concrete in civil engineering labs.