The rise of “green” concrete

Green Cement

If pressed to name a common substance that, on its face, seems least likely to be eco-friendly, I might choose white Elmer’s glue or Saran-Wrap.  But Portland cement could easily top that list as well.  It is one of the most ubiquitous materials in the world and stands as a basic symbol of industrial development throughout the past two centuries.  Portland cement (which, through sheer market domination, has come to be synonymous with “ordinary” cement) is dirty, dingy, and absolutely essential.  Its manufacturing process is largely unchanged since its creation in England in the early 1800′s.  Concrete is created by blasting raw material (primarily limestone) out of the ground, super-heating it in kilns to separate the elements, and then mixing with water and other carbonates to create a chemically reactive slurry.  This process requires an incredible amount of fuel and industrial infrastructure.  The concrete is stored in silos before eventually being transported to market in that diesel-chugging truck that will inevitably drive in front of you on the highway.  By most measures, every ton of cement produced releases an equivalent ton of C02 emissions – and global consumption rose 9.9% last year.

But “green” concrete’s moment may be nearing.  It features prominently in December’s Smithsonian magazine.   The Calera Corp., based in California, recycles power plant emissions by filtering them through seawater in order to form the carbonate base of cement.   Last year, the startup C-Crete Technologies won the M.I.T. Entrepreneur Competition for its nano-engineered cement that contains emissions.   And Sriya Green Materials, Inc. in Georgia has invested $10 million into a test plant for “small batch” production that uses the same raw materials, but lower temperatures and smaller particles in order to drastically lower energy use and production time.  If all goes according to plan, a 200,000 square foot commercial plant will follow close behind.

The promise is unmistakable: a carbon-neutral building material that could, in theory, remove a primary factor in global warming.  But can concrete really “absorb” CO2?  The companies fostering the boomlet are understandably hesitant to delve into exact details about their methods.  Nikolaos Vlasopoulos, chief scientist at Novacem (the start-up profiled in the Smithsonian article), will only allow that he has experimented with swapping the limestone for a magnesium oxide compound.  This, he says, has the effect of setting the cement’s bonds, trapping the emissions, and eliminating the need to superheat the limestone.  A number of papers currently under peer review are said to be assessing the chemical viability of this new formula.

If the methodology is sound, the biggest remaining question is scaleability.  Companies advancing “green” concrete are reluctant to compare costs to Portland cement at the moment because the latter will continue to be far cheaper until the former can produce at comparable volume.  Achieving that will require huge buy-in from domestic manufacturers in an industry that is known for its caution.  The new innovators will need to overcome durability concerns as well, since traditional Portland cement has the advantage of tried-and-tested market familiarity.

As it happens, green cement may get a timely boost from the United States government.  In 2013, new EPA regulations on mercury emissions are set to take effect.  Since mercury is a byproduct of concrete production, manufacturers will be required to implement carbon capture and storage (CCS) processes to the tune of billions of dollars.  Investors are hoping that, when caught between a rock and a hard place, the cement companies will consider “green” cement as a viable and sustainable long-term alternative instead of simply tacking on stopgap measures to satisfy the new requirements.

Globally, all eyes are on India and China, the dual engines driving a rise in construction even during a time of economic slowdown.  Unlike the U.S., the two countries are unencumbered by regulations and can almost single-handedly keep the price of Portland cement low via prodigious consumption.  China may soon control the cement market inAfrica entirely.  However, China recently agreed to test batches of the “green” concrete in a few of its development projects.  Seeing as it is still in short supply, the material will only be used for “patching” and fixes rather than new construction.  If these early experiments prove successful, entrepreneurs will gain leverage to press for wider adoption.  Until “green” concrete receives a large buy-in, the emerging technology will likely continue to exist on the margins and require R&D capital to keep it afloat.  But recent developments give advocates reason for hope.  As the world seeks radical ways to counteract emissions, the solution may ultimately lie in reinventing one of industrial society’s oldest stand-bys.


Hinshaw, Alex.  “Cement may pave Africa’s road to the future, but will China undercut that, too?”  The Christian Science Monitor.  8/18/2010.

Karkaria, Urvaksh.  ”Startup will build plant to manufacture green cement.”  Atlanta Business Chronicle.  9/13/2010.

Rev, K.R. “Making Cement Green.” Forbes Magazine.  9/20/2010.

Barringer, Felicity.  ”E.P.A. Cracks Down on Cement Emissions.”  The New York Times.  8/10/2010.


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