Construction, meet Climate Tech.
Construction contributes over 10% of annual carbon emissions and that number is growing as populations and economies continue to grow too. But aside from the fuel costs of heavy machinery and the variety of materials used in projects, the biggest offender in construction is concrete which, alone, makes up around 8% of those annual emissions. Every year, over 10 billion tons of concrete are used around the world. What is it exactly about concrete that makes it responsible for the emissions?
Concrete itself is actually primarily made up of aggregate (gravel or sand), water, and Portland cement. The cement acts as a binding agent that’s activated when mixed with water and while the composition varies depending on regional climate and intended use, cement usually makes up only about 10–15% of concrete composition. But the use of cement is a double whammy of emissions: 1) a lot of fossil-fueled-heat is needed to process the cement and 2) a hefty release of CO2 occurs during the chemical reaction of binding.
Unfortunately, many believe that cement and concrete are necessary evils of economic development in cities and there’s little evidence to support that usage is slowing down.
Luckily, some tech companies have decided to zero in on this issue and figure out how to tackle it. One idea that’s been floated is to capture the carbon release while concrete is being mixed like CarbonCure proposes. Carbon capture and storage techniques as a whole are getting increasingly more attention thanks to research by scholars like M. Granger Morgan at Carnegie Mellon University, but much of the work is still at the basic research or demonstration stage; far from being soon implemented into construction sites worldwide.
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Another possible solution is to tweak the recipe of concrete itself. That’s what Montreal-based Carbicrete is trying to do. They inject the concrete mixture with steel slag to achieve the same strength and structural integrity of original concrete mixtures and claim to produce a final product that’s actually net carbon-negative! The concrete has to cure in a special chamber though, which means that this technique can only really work for precast concrete (think: CMU building blocks or, individual pieces of a project that are pre-fabricated and need to be transported on-site). Precast concrete has the advantage of better quality control and speedier curing times, but most projects can’t justify the costs compared to cast-in-place. So I worry about the widespread adoption of technology like Carbicrete’s.
Another startup, Solidia, based out of New Jersey, has developed two branches of technologies: sustainable cement manufacturing (where fossil fuels traditionally are needed to provide heat) and sustainable concrete curing (where CO2 emissions are released). When used together, their patented system can cut the carbon footprint of concrete by up to 70% as a whole. I’m excited to follow this 60-person company’s continued growth into commercial markets.
One area I’m looking forward to seeing more innovation is the use of artificial intelligence to optimize the composition. As mentioned earlier, the particular recipe of a batch of concrete and amount of cement needed is dependent on a variety of things. These include: the humidity and temperature of the region, the intended structural purpose and required compressive strength, the rate of loading, and the size of the aggregate being mixed in.
Just as there is with baking a cake, surely the proportion of ingredients can be perfected. That’s where AI can come in. Promising research out of the University of Southern California and IMB’s Watson Research Center shows that a generative AI model trained on environmental impact data can seek out that ideal concrete recipe, optimizing for lowest carbon emissions while keeping the strength and safety requirements as constraints. I’d love to see models like this shared with the structural engineers responsible for providing the mixture design and specifications for projects to help move the needle on the industry’s carbon emissions.
