As the most widely used construction material in the world, concrete is also a major greenhouse gas producer. Estimates suggest that two billion tons of concrete are produced annually, and producing one ton of cement creates one ton of greenhouse gas emissions.
The Concrete Joint Sustainability Initiative notes that concrete production is nearly 40% more energy efficient that it was in 1972, but as the use of concrete continues to increase (the Portland Cement Association estimates 4% growth in 2014), efforts to further improve sustainability are gaining interest.
Here's a look at four ongoing projects that could significantly change the environmental impact of concrete.
- A new discovery by MIT researchers could mean stronger concrete that has less of an impact on the environment. According to the MIT News Office:
The findings come from the most detailed molecular analysis yet of the complex structure of concrete, which is a mixture of sand, gravel, water, and cement ... The new analysis suggests that reducing the ratio of calcium to silicate [in cement] would not only cut those emissions, but would actually produce better, stronger concrete. These findings are described in the journal Nature Communications by MIT senior research scientist Roland Pellenq; professors Krystyn Van Vliet, Franz-Josef Ulm, Sidney Yip, and Markus Buehler; and eight co-authors at MIT and at CNRS in Marseille, France.
The news has also made headlines in the general media, including reports in Scientific American and Phys.org, and the next step is to determine whether the findings at the molecular level translate to a practical scale. Read More
- Alchemy Geopolymer Solutions was recently awarded the inaugural LA StartUp Prize, a competition connecting entrepreneurs with investors, for work on geopolymer concrete. The product, which uses fly ash instead of Portland Cement, produces significantly lower greenhouse gas emissions and offers a number of other benefits in terms of strength and higher fire resistance. Team leaders, including Carlos Montes, chief technology officer and Dr. Erez Allouche, CEO of AGS, developed the operation through research at Louisiana Tech University. Read more about the award here
- A new form of cement, developed in Switzerland, has the potential to reduce the carbon footprint of concrete by as much as 40%.
According to Karen Scrivener, head of the Construction Materials Laboratory at Switzerland’s Ecole Polytechnique Federale de Lausanne (EPFL) and principal investigator of the project, the cement consists of a mixture of calcined clay and ground limestone. When the two materials are combined together the aluminates from the calcined clay interact with the calcium carbonates from the limestone to produce a cement paste which is less porous and thus significantly stronger ... Scrivener’s team believes the Limestone Calcined Clay Cement (LC3) they have developed has the potential to become the benchmark material for low-carbon concretes. Read More
- A Stanford University professor is looking to develop a concrete that can act as important tool for reducing power plant carbon emissions. Brent Constantz, also founder and CEO of Blue Planet, shared his vision in this video.
He spoke at the BuildWell conference in San Francisco earlier this year, and according to Green Building Advisor:
Constantz is focusing on a very different type of cement: a calcium carbonate cement. The calcium is derived either from seawater or — in more inland locations — from brine, and the carbonate comes from the carbon dioxide in power plant flue gases. He envisions a system in which the CO2 is extracted from flue gases to produce both a calcium carbonate cement and limestone aggregate.
Blue Planet, which has attracted some large investors, believes that concrete produced with their CarbonMix cement and limestone aggregate would be carbon-neutral or even carbon-negative, meaning that the more of it you use the more carbon is sequestered — or pulled out of the atmosphere and forever locked up.
Blue Planet is carrying out research at one of California’s largest power plants: a natural-gas-fired plant on the coast at Moss Landing (south of San Francisco). The Moss Landing power plant, now owned by Dynegy, produces four million tons of CO2 per year — CO2 that is contributing to global warming.
Read more from the Massachusetts Institute of Technology >>