How Can We Reduce Concrete’s Hefty Carbon Footprint?

[sue4e3]

A roomful of materials scientists, gathered at UCLA for a recent conference on “grand challenges in construction materials,” slowly passed a brick-size white block around the room. They held in their hands, briefly, part of the solution to one of those grand challenges. The white block, rock solid and surprisingly lightweight, was a new alternative to cement, the glue that holds together aggregate, or crushed rock, to make the world’s most ubiquitous building material: concrete.

Production of cement — and by extension, concrete — has a large environmental footprint, mostly due to the huge amount of energy it takes to heat limestone, cement’s key ingredient, and the subsequent chemical process it undergoes. The process of creating cement emits upwards of 80 percent of the cement’s weight in carbon dioxide and accounts for about 5 percent of human-generated CO2 emissions annually. Though the white block’s production still requires some of the CO2-emitting fuel use of typical cement making, CO2 is also one of the ingredients used to create it. About one-third CO2 by mass, the cementlike substance reduces its carbon footprint by sequestering CO2 inside the finished product.

Concrete, and the cement that binds it, is the most widely used material in the world, and its usage is on the rise. From 2011 through 2013, China used more than 6.5 billion metric tons (7.2 billion tons) of cement — more than the U.S. used in the entire 20th century. Between 2006 and 2050, global production of cement is expected to increase to between 3.7 billion metric tons (4.1 billion tons) and about 4.4 billion metric tons (4.9 billion tons) a year. Since concrete’s not going away, reducing the carbon intensity of its production is becoming a global imperative. New technologies and approaches are being developed to cut down on concrete’s environmental downsides — everything from utilizing industrial by-products to reduce cement usage, to recycling existing concrete, to producing self-healing concretes that reduce the need for new concrete, to creating entirely new materials.
http://www.climatecentral.org/news/how-can-we-reduce-concretes-carbon-footprint-20274

[Gregorian]

1. In 2 years, China used as much concrete as America for the entire 20th century!

Fuuuuuuuuuck! That is hard to even fathom.

[SamKnause]

2. Hempcrete

[Esse Quam Videri]

3. As someone in the construction industry,

I appreciate you posting. Very interesting.

[sue4e3]

4. Your Welcome

[cprise]

5. I've also read about 'green concrete'

by a company called Calera Corp. It is supposed to be carbon negative (it sequesters carbon IIRC).

[muriel_volestrangler]

6. They're mentioned in this roundup of activities:

https://www.technologyreview.com/s/535646/what-happened-to-green-concrete/

I think the problem all the projects face is that their processes use materials that are available on a limited scale, compared with the vast amounts of limestone mined to produce cement in the standard way. They help a little, but can't replace the bulk of the industry.

[NickB79]

7. Step one: stop building and consuming so much stuff

If we can't do that, then nothing else we can do will make enough of an impact to change the trajectory we're currently on. Making "greener" concrete is like a morbidly obese person cutting 50 calories a day out of a 5,000-calorie lifestyle and saying good enough: it won't do nearly enough to save his life by itself. The only significant way we reduce our carbon footprint is to stop consuming so much of the planet's resources.

And the only way we ultimately stop building so much stuff is to have fewer children and live a life that demands less new stuff all the time.

[Nihil]

10. +1 on all of that. (n/t)

[NNadir]

8. There is going to be an excellent paper published on this subject in the near future. I have...

...read the paper in manuscript, and have promised not to say another word about it, but I'll link it when it appears.

[sue4e3]

9. can't wait