Tuesday, October 6, 2009

Enough About Coal – Let’s Hear About Concrete!


Where would we be without concrete? It's the most prevalent building material on the planet. Without it, we'd be a world of one- and two-floor structures. The Statue of Liberty would be elfin rather than the largest 19th-century concrete structure in the U.S. No Roman Coliseum or Pantheon. No theatre at Pompeii. No Pont du Gard Aqueduct in France. No Empire State building or Sears Tower. No… well, you get the idea. Without concrete the world would, indeed, be flat, so to speak.

But all of our building with concrete comes at an enormous environmental cost because about 5 to 8 percent of all human-generated atmospheric CO2 comes from the concrete industry.

Portland cement, the binding agent in concrete, is the bugaboo -- producing it takes massive amounts of energy which, in turn, generates an enormous amount of CO2 -- for every pound of cement we create, we pump about one pound CO2 into the air. You can grasp the weight of the problem when you understand that we turn out more than 2.6 billion tons of Portland cement every year.

So, in addition to developing clean energy sources, we need to do a bit of work on cementitious materials. One green alternative, inorganic polymer concrete (geopolymer), is emerging with others that substitute "fly ash" -- one of the planet's most abundant industrial by-products -- for Portland cement. Geopolymers can reduce CO2 emissions significantly and produce a durable infrastructure that could consistently last centuries rather than decades. And the use of fly ash would eliminate the need for hundreds of thousands of acres on which to dispose of coal combustion products. Geopolymer concrete resists corrosion better than concrete with Portland cement; it exhibits high compressive and tensile strengths, and less shrinkage.

But for me -- and don’t get me wrong, I’m a Portland cement-lover from way back -- geopolymer is the concrete of choice for all of the aforementioned reasons: its binding agent is fly ash, which is abundant, cheap and ready to use now; it would reduce greenhouse gases and enable us to build a more durable infrastructure… AND it would buy us more time to implement those green energy sources -- solar, wind, geothermal, tides and others -- that seem to be taking forever to put to use. 

Let's hear some noise for geopolymer concrete, the eco-friendly building material that would mitigate the use of Portland cement and its enormous CO2 production.

Read about the University of Michigan’s Advanced Civil Engineering – Materials Research Lab, which is developing yet other ideas, such as bendable concrete, for a sustainable concrete future with an eye on durability and a reduced environmental impact. 

Also, read about:


The University of Michigan Center for Concrete Performance