Historically, startup founders and investors haven’t focused much on concrete.

After all, this is literally the industry that brings us the mortar in “brick and mortar.” It’s the quintessential infrastructure-heavy, capital-intensive industrial sector that startup investors like to avoid.

Nonetheless, inconvenient as it may be, we all still live in the physical world. And given the climactic upheaval humans have helped unleash on our assigned planet, we’re increasingly under pressure to do more to keep it livable.

Enter clean concrete. Over the past two years, investors have poured hundreds of millions into startups working on reducing the carbon footprint of this most ubiquitous building material. For a sense of where the money is going, we used Crunchbase data to assemble a list of 20 such companies funded in the past couple years:

A recent funding trend

The bulk of funding is comparatively recent. To date, the companies on our list have collectively raised around $436 million in equity funding — of which around 70% has come in the past two years.

The biggest round of the year, meanwhile, was just this month. CarbonCure Technologies, a Nova Scotia-based company that has developed technology for concrete producers to inject captured CO2 into fresh concrete, picked up $80 million in a growth round led by Swiss impact investor Blue Earth Capital.

CarbonCure’s marketing pitch plays up some oft-cited stats around the building industry’s carbon footprint. Currently, industry sources estimate that existing and under-construction buildings generate roughly 40% of annual global CO2 emissions. Of that, roughly a third comes from construction and building materials.

Concrete, of course, is a huge component. It’s not uncommon to see concrete referred to as the second most used substance on the planet, after water.1 More than 10 billion tons of the stuff get produced annually in what’s estimated to be a $440 billion-plus global industry.

But while concrete’s dominance in the building industry has been solid for a long time, its popularity with startup investors seems tied to the more recent rise of climate-focused investors.

The list of funding rounds this year includes some of the more prominent greentech-focused investors as lead backers, including Breakthrough Energy Ventures, Microsoft Climate Innovation Fund and Lowercarbon Capital. It seems their portfolios can’t be complete without some clean concrete in there.

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Illustration: Dom Guzman