Environment

MIT's new cement recipe could cut carbon emissions by more than half

MIT's new cement recipe could ...
A study carried out at MIT suggests that altering the quantities of materials in cement mixing could substantially reduce CO2 emissions (Photo: Shutterstock)
A study carried out at MIT suggests that altering the quantities of materials in cement mixing could substantially reduce CO2 emissions (Photo: Shutterstock)
View 1 Image
A study carried out at MIT suggests that altering the quantities of materials in cement mixing could substantially reduce CO2 emissions (Photo: Shutterstock)
1/1
A study carried out at MIT suggests that altering the quantities of materials in cement mixing could substantially reduce CO2 emissions (Photo: Shutterstock)

As one of our most relied upon construction materials, concrete makes a significant contribution to our overall carbon emissions. Calcium-based substances are heated at high temperatures to form the cement, a process that produces carbon dioxide. But by slightly altering the quantities of materials used, scientists from MIT have uncovered a new method of cement mixing that could reduce these emissions by more than half.

Concrete is generally made by mixing gravel, water, sand and cement. To produce the cement, calcium-rich materials such as limestone are cooked up, typically with clay, at temperatures as high as 1,500° C (2,732° F). The energy required to heat up the mix combined with a resultant chemical reaction generates carbon dioxide, a process the researchers say is responsible for between five and ten percent of total industrial greenhouse gas emissions.

By examining the makeup of cement, the MIT team, led by senior research scientist Roland Pellenq, found that reducing the ratio of calcium to the silicate-rich clay substantially reduced the output of carbon dioxide. Typically, calcium to silica ratios can vary between 1.2 to 2.2, though 1.7 is seen as the standard for producing cement. By compiling a database that compared the chemical makeup of the different ratios, the researchers determined that 1.5 ratio was in fact the optimal mix. According to the researchers, this slight change in calcium levels could reduce carbon emissions by as much as 60 percent.

Furthermore, with the altered ratio the mix proved to have a higher resistance to fractures, with the researchers claiming this is due to the molecular structure transforming from a tightly ordered crystalline to a disordered glassy structure. Pellenq describes the mix of 1.5 to be "magical ratio," with twice the mechanical resistance to fractures of normal cement.

The analysis of the cement mix was carried out at a molecular level, meaning the team will need to conduct further research to make sure it can apply to engineering scale applications. Pellenq says the formula could find a home in oil and gas industries, where more resistant cement could be particularly useful in preventing leaks and blowouts.

The research was published in the journal Nature Communications.

Source: MIT

14 comments
David Rochlin
Grancrete lite. Grancrete is a product already on the market with similar properties, based on materials developed by U.S. Department of Energy research to encapsulate nuclear waste. It uses a formula for cement involving Magnesium, instead of Calcium as a reactant, as I recall, actually absorbs CO2, and has greater strength than ordinary cement.
MattII
Okay, if that can be upscaled it would be pretty cool.
Richardf
Fasinating stuff but more needs to be done in the areas of removing old concrete and these newer versions as rapidly as new forms of construction are in operation. A building can be biult in 15 days this number will drop to probably a week and then as robots enter the feild less. However a building takes longer to get rid off. Site management , pirotecnics and then concrete smashers and big trucks to recycle and dispose of the stuff. A hyrocloric approch to concrete should be the next step. Very strong yet very easy to dismantle. Bactria have been shown to break down metal gurders etc but may risk spreading to ajoing buildings. A top down approch of disoloving a building via 1 chemical or 2 lazer cannon made to attack the composites of the building. Older buildings could be addressed with a diffrent approch. Any feed back welcome on such approches¿
BeWalt
Amazing. Precise process control, that's where the magic happens. But now how do we get the industry to care? Here come the dirty words: Government intervention! Regulations! Taxes! A textbook case for carbon taxes.
VirtualGathis
In a discussion regarding this on NextBigFuture a construction contractor with concrete experience commented that there is a break point right where these MIT students are aiming. Something like 1.2:1 to 1.4:1 the contrete flash cures and loses 60% of it's strength. That's why they aim for 1.7 as it avoids the flash cure when the mixing machines fail to get the ratio absolutely perfect. He suggested that these students were too hasty in publishing. They should have run a few thousand feet in bulk batches before declaring they had a "holy grail" solution to fixing concrete as it would have forced them to use the same machines in use today and not these tiny lab batches and lab machines. It would require a complete revamp of the mixing machines industry wide to implement the tighter controls on the ratio.
alien678
Doh... check out hempcrete... over 100+/- , structures 250K$$$ and up have been built in France in the last five years, there are bridges 600 years old in Europe made of Hempcrete... also check out www.envirseal.com... their M50 increases the shear strength 200%, use www.scaleban.com treated water kick everything up another 17%... but anyone who has read the "Space Merchants" knows none of this going to happen anytime soon.
StWils
First, Great story! Second, like many things more study is needed to make this a useful reality. I would like to know how well this concrete compares to pozzolan cements. There are many structures built by the Romans that are still completely functional after two thousand years. There is a sea wall at Bari that still defines part of the harbour exactly as intended when it was built during Emperor Constantine's rule. Third: BeWalt has it absolutely backasswards, Governments set standards and level the playing field in ways that free markets do not and will not. As just one example the disaster CAUSED by BP in the Gulf of Mexico was driven by market forces and a large measure of greed. Also, GM, Ford, GE, and many other companies have repeatedly hidden, lied about, concealed, etc product defects for purely greedy reasons. Market Forces alone will never make any company own up, up front, on any kind of trustworthy, reliable basis.
Lbrewer42
This is supposed to be about science. Google Game over IPCC. The IPCC data (The UN's go-to for information on the THEORY of global warming - and the pro-climate change bastion of information) was compiled into one place and it is a proven, scientific FACT that there has been no warming caused by manmade sources these last 15 years. Despite the "proven science" of AGW, it has been one of the biggest non-scientific lies foisted upon the public that was ever created. The information caused many pro-AGW sites to start talking about the 1 year "hiatus" AGW has taken. When confronted with this, the UN made a statement they would not abandon their work in making regulations about AGW giving the lame excuse that they just wanted to be sure. Don;t just beleive someone telling you ADW is science. Become educated by doing your own research - on both sides of the issue. You will find the AGW crowd always has fudged their data/reports. So although the pseudo-science community may lad this concrete b/c of less emissions, in reality the point it moot. Either that or the palm trees the initial global warming "science" stated as absolute fact as being grown on the shores of Lake Erie by the year 2000 are of the invisible kind. I have been following the evolution of this argument and lie now since it was first started. All it has really done is filled a lot of bureaucrat's pockets with our tax dollars whilst giving more governmental control over our lives. But please... if you believe this is wrong, prove it with some homework of your own that will include looking at the actual data instead of taking your professor's words. Secondhand knowledge can be (and in the case of pro-AGW ideas) as reliable as rumor. So although this post could be considered secondhand - at least I am willing to admit it and say prove it for yourself.
Synchro
@VirtualGathis did you actually read the article? "the team will need to conduct further research to make sure it can apply to engineering scale applications". @Lbrewer42 I'm intrigued by how you intend to prove something using a lack of data. Lining pockets? That's all for the fossil fuel companies, who get 20 times as much for taking a dump in our atmosphere. Why would you ever think that's preferable? And of course: "What if it's all a hoax and we made the world a better place for nothing?"
Gannet
http://www.tececo.com.au/simple.eco-cement.php