In Search of Cement Replacements
Could we replace cement as the vital element in concrete some day? We look at two alternative answers to this question.
The Problems with Cement
Portland cement dominates in the construction and road building industries. From an environmental point of view, cement is not the perfect solution. The cement industry accounts up to 7% of the world’s carbon dioxide emissions. For every 600 kg of cement, approximately 400 kg of CO2 is released into the atmosphere.
It is possible to recycle concrete by crushing it and using the gravel e.g. in road construction. However, the demand for new concrete is huge and increasing. According to The Washington Post, China used more cement between 2011 and 2013 than the U.S. used in the entire 20th Century. The worldwide production of cement has increased from 3.3 billion tons in 2010 to 4.2 in 2016. Even that is not enough; shortage of cement is a real problem in some countries.
The following endeavors introduce new ways to make concrete from industrial by-products.
During his Ph.D. studies at the University of Arizona, David Stone came up with an idea to use iron carbonate as a key ingredient for a cement replacement.“The whole process is green,”David told in an interview for PBS News Hour. “This is a carbon-negative process that helps to trap the greenhouse gas, carbon dioxide.” The process can use a by-product from steel mills. “I discovered that there was this material called steel dust that is not recycled, so it typically goes straight to the landfill.” Silica is added to the mix, and that comes from ground-up glass.
Stone won a prize for his innovation, and the University of Arizona helped him secure a patent. It also licensed the technology for Stone. He became a founding member of a Nevada company called IronKast. It now owns an exclusive patent on the iron-carbonate based cement called Ferrocrete™.
According to IronKast, Ferrocrete™ performs better than Portland cement. It is stronger and does not break down when exposed to high heat or salt water. IronKast is currently focusing on pilot applications in marine environments.
A New Type of Concrete
The Finnish City of Lappeenranta and the Lappeenranta University of Technology (LUT) with their partners are developing a sustainable composite that could replace concrete. The three-year circular economy project combines forest and mining industry side streams. Their EU-funded project will also develop 3D printing.
“With concrete and 3D printing of the new material, it may be possible to escape the rigid design language of building and to create curved and even functional shapes. The new material could be used to manufacture, for example, more aesthetically pleasing noise barriers, park benches, and skateboard ramps. That is why design companies are involved in our project,” say advisors Terhi Jantunen and Eeva Pihlajaniemi from the City of Lappeenranta.
The total cost of the Urban Infra Revolution project is EUR 4.2 million, of which 80% will come from the Urban Innovation Action (UIA) programme of the ERDF. The rest will be covered by the organizations participating in the project.
FIMAtec, a Finnish robotic 3D printing innovator, is also involved. “The EU project acts as a natural continuation for FIMAtec’s development path, as new eco-friendly construction materials with superior features will change the world significantly already in the near future. FIMAtec wants to be involved in this development and act as a pioneer,” says Antti Korhonen, Director of Business Development at FIMAtec.
Will we see mass use of these or other cement replacements? It will depend on the availability of their source materials and the cost of production. It is likely that no single solution will replace cement; instead, there will be a number of substitutes for different purposes and locations.