Low-Carbon Cement Makes a Dent in Climate Change, One Slab at a Time

It’s probably been awhile since you thought about cement. And by “awhile” I mean, well, ever. Fair enough. Cement is not exciting—it’s just there.

And by “there” I mean, well, everywhere. In fact, in its most common form (concrete), cement is the second-most widely used material on our planet (after water), with global production topping four billion tonnes annually. The Cement Association of Canada estimates Canadians use enough of it every year to fill Toronto’s Rogers Centre from floor to ceiling with concrete 23 times over.

All of which turns out to be a bit of a problem when concerned about climate change. Despite the obvious advantages of cement—no other building material is quite so strong, safe, reliable, versatile, and affordable—it remains a massive source of CO2 emissions, accounting for about 8 per cent of the world’s annual total. To put that in perspective, if you were to list the worst emitters of CO2 the “country” of cement would sit in third place, behind only China and the United States.

The good news: a number of recent innovations have the potential to change this, one slab at a time. New Jersey start-up Solidia is tackling the chemical process that creates cement. By using carbon dioxide instead of water as a binding agent, and a lot less heat, the company has cut emissions by some 30 per cent. CarbonCure, a company in Nova Scotia, has made concrete into a carbon sink by mineralizing CO2 and blending it into the ready-mix. Meanwhile in Montreal, Carbicrete has created a new formulation for concrete by using ground steel slag, a steelmaking by-product, for a binder instead of cement. And then there’s BioMason, a North Carolina company attempting to make concrete obsolete altogether, producing bio-engineered bricks and blocks formed from a soup of calcium, waste aggregate, and bacteria, a process that generates 99 per cent less CO2 than traditional cement.

In the fight against climate change, we tend to celebrate what we can see: the blue bins, the electric cars, the windmills. Sure, these things make us feel good, but they mask a whole other front in this battle—most of which is invisible and underappreciated but immensely consequential. What would happen if we could all stand up and cheer a truck full of boring, grey eco-cement as much as we do that exciting electric supercar? We could build another, greener world—or at least, a mighty solid foundation for one.