Concrete is expected to contribute 12 per cent of global greenhouse gas emissions by 2060, thanks in large part to one of its main ingredients, cement, which is currently responsible for as much as eight percent of emissions.
But there's a movement to make concrete greener by reducing its carbon footprint. The Global Cement and Concrete Association has promised carbon-neutral concrete by 2050, a goal Canada wants to help the industry achieve.
"We live in a world that's still going to need cement and concrete," said Keith Brooks, programs director with Environmental Defence, citing the physical infrastructure necessary to create denser, more energy-efficient cities. "The industry's going to have to do its part to get there. But it is possible."
There are two reasons why manufacturing cement releases a lot of carbon: the combustion of fossil fuels typically used to heat the kiln, and the chemical reaction that releases carbon stored in limestone.
Reducing the carbon currently used to fire the kilns is already in progress. Adam Auer, vice-president of environment and sustainability with the Cement Association of Canada (CAC), said that almost all cement producers in Canada use some portion of lower-carbon fuel, such as waste biomass, which is mostly wood leftover from things like construction and demolition.