Much Ado About Concrete > ENGINEERING.com

Concrete is the second most used material on the planet after water. If you convert the social and environmental costs of the material into externalities, as is the ubiquitous practice in business, the stuff becomes relatively cheap. If concrete were a country, it would be the third largest emitter of carbon dioxide behind the U.S. and China.

But we’re entering an era where externalities can no longer be considered external and, in the case of concrete, there are a lot of costs to be accounted for that requires an entirely new look at the way it has been used and whether it should be used in the future.

This article breaks down the role of concrete in global infrastructure and what the future of the material might look like.

Concrete’s Carbon Footprint

Most recent estimates cite concrete production as responsible for up to 8percent of global carbon dioxide emissions. To understand where these emissions come from, it’s necessary to understand how concrete is made.

Roughly half of the emissions stem from the chemical process to produce cement, called calcination. When limestone is heated at temperatures of over 825 °C (1,517 °F) for about 10 hours, it breaks down into calcium oxide (lime) and carbon dioxide that is released into the atmosphere. The energy used to heat the kiln for calcination accounts for about 40 percent of the material’s total emissions.

In the case of the world’s most common cement, Portland cement, the lime is combined chemically…

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