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Concrete can be catastrophic for the environment.Drazen_/iStockPhoto / Getty Images

Concrete is the single most abundant human-made material on Earth. It’s most likely beneath you right now.

Some 70 per cent of the world’s population lives in a building made with concrete. Every year – and year after year – the world produces enough concrete to pave over the Great Lakes.

But concrete is also catastrophic for the environment.

According to data from the United Nations Environment Programme, the production of concrete is the source of 8 per cent of humanity’s carbon dioxide emissions. If the global concrete industry were a country, it would be the third-largest carbon dioxide emitter, surpassed only by China and the United States.

But what if, rather than releasing carbon dioxide into the atmosphere, concrete absorbed it instead?

One Canadian technology company has produced an alternative concrete that does exactly that.

To make this special blend, “you get rid of the cement,” says Chris Stern, chief executive officer of Montreal-based Carbicrete.

Most of concrete’s carbon dioxide emissions come from manufacturing its binding agent cement. This process involves heating limestone to 1,400 C, generally using a fossil-fuel source. The heat causes the limestone to break down and release another dose of carbon dioxide.

Over the next four decades, the equivalent of 500 New York Cities will be built around the world.

2020 Global Status Report for Buildings and Construction, United Nations

The product Carbicrete, on the other hand, uses steel slag, a waste material from the steel-making process, to replace cement as a binding ingredient. The slag is injected with carbon dioxide captured from industrial plants. The curing process converts the carbon dioxide into a mineral; not a trace of it remains.

A typical concrete block includes two kilograms of cement, Mr. Stern explains. By eliminating cement, Carbicrete reduces two kilograms of emissions. Add the kilogram of carbon dioxide injected during curing – and a single block flips the carbon footprint from a release of two kilograms to an absorption of one kilogram.

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Carbicrete uses steel slag, a waste material from the steel-making process, to replace cement as a binding ingredient.Handout

“We do three things really well,” Mr. Stern says. “We get rid of cement; we get rid of slag and get rid of CO2.”

Regulatory testing proves Carbicrete is 30 per cent stronger than conventional concrete. Furthermore, the precast products are between 10 and 20 per cent less expensive than regular precast units, “because the materials cost less,” Mr. Stern says.

A collaboration with Quebec concrete manufacturer Patio Drummond will see Carbicrete ramping up production to 25,000 units per day, while the first building using Carbicrete is set to be built in Canada at the start of next year.

Since Carbicrete’s process can be integrated into any existing concrete production plant, the five-year-old company plans to license the technology for its “negative emissions concrete,” as Mr. Stern calls it, to manufacturers around the world.

Until then, the building industry can choose from a few other Canadian companies making concrete that emits lower amounts of carbon dioxide than the regular stuff.

About 400 concrete plants around the world use CarbonCure’s concrete technology. Like Carbicrete, CarbonCure also introduces recycled carbon dioxide into its recipe, but the recipe still includes cement.

The resulting cement, however, is stronger than conventionally made concrete, so builders can use less of it in their mixes. The company says CarbonCure concrete has a 5-per-cent lower footprint than regular concrete.

Lehigh Cement blends cement with extra limestone to reduce the carbon footprint of its cement mix. The manufacturer claims its new product, EcoCem Plus, has a carbon footprint 32 per cent less than regular concrete.

One of the country’s largest manufacturers, Lafarge Canada, has also stepped up its green game, with EcoPact concrete and EcoPlanet cement. According to Jill Truscott, manager of communications at LaFarge Canada, EcoPlanet adds carbon to low-emissions raw materials to make a stronger cement that leaves a 30-per-cent smaller footprint than standard cement.

At its cement plant in Richmond, B.C., Lafarge uses alternative fuels and has implemented technology that captures dioxide produced from the industrial process. The next phase in its goal to create a circular cement solution is to put in place a system to reinject the carbon dioxide into eco-cement mixtures, Ms. Truscott says.

“We will continue to innovate and bring to market the greenest solutions,” says David Redfern, CEO at LaFarge Canada. “I’m excited about the new ideas that keep coming out. Lafarge will be there to support increased urbanization – there is no turning back now.”

Making builders green with innovation

The building industry is the world’s largest source of carbon dioxide emissions. Yet over the next four decades, the equivalent of 500 New York Cities will be built around the world, according to the 2020 Global Status Report for Buildings and Construction, published by United Nations and Global Alliance for Buildings and Construction. Here are three Canadian companies aiming to make buildings more environmentally sustainable.

Miru Smart Technologies

Ordinary office windows increase energy use. Miru’s smart windows are electronically tinted to optimize natural light and keep rooms cool – providing significant energy savings. The technology involves the use of electrochromic coatings – materials that change colour and transparency when fitted with electric voltage – which began developing at the University of British Columbia three years ago.

Nexii Building Solutions

The construction of a hotel exterior usually takes at least a year and a huge crew to complete. Using Nexii prefabricated materials, a nine-storey Courtyard by Marriott hotel, in Nanaimo, B.C., should take just a handful of trades people about 10 weeks to finish, according to a Nexii news release. The Vancouver company, founded in 2019, has developed highly insulating panels that eliminate the need for framing, insulation, drywall and exterior siding. The manufacturing process emits 30-per-cent less carbon than concrete and steel and, once constructed, the thermos-like building slashes energy use by 60 per cent.


Cooling down buildings only makes the world hotter. Evercloak wants to break the air-conditioning cycle, says Evelyn Allen, co-founder and CEO of the three-year old Waterloo, Ont.-based startup. The solution is a nanoengineered membrane that cuts the energy needed for air conditioning by more than half. Evercloak is scaling up its proprietary graphene membrane manufacturing process to commercialize the breakthrough AC technology.

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