We're worried about the emissions from our cars, but how about the roads? Cement production is actually a major contributor to worldwide carbon dioxide emissions. As this ScienCentral News video explains, researchers at MIT are using nanotechnology to find a solution.
Building at the Nanoscale
Concrete is one of the world's most widely used materials -- it's hard to imagine life without it. But having to make so much is a problem. Production of concrete's key component, cement, accounts for at least five percent of global carbon dioxide emissions. Franz-Josef Ulm and his team at MIT hope to change that.
"Despite its ubiquitous presence in our daily life, in roads, infrastructure, concrete has kept its secret for a long time," he says.
The secret lies in cement's nanostructure, the arrangement of its atoms. The researchers studied cement from manufacturers around the world. Using a nano-sized needle, they poked the cement samples, and measured the indentations using an atomic force microscope. What they found was that all the different cement samples exhibited the same organization at the nano-level.
WEB EXTRA: MIT's Markus Buehler explains the nano-engineering of cement
In fact, the high density of cement is explained by this nanostructure. Its clusters of atoms are stacked like a tightly packed pile of oranges. "If you take the oranges and put them in an organizational scheme, like a pyramid in a grocer shop," says Ulm, "this packing density actually characterizes concrete materials at the nanoscale of the material." This high packing density accounts for the strength and stability of cement, which makes it useful for structures like tunnels and bridges.
Unfortunately, current cement manufacturing methods require very high temperatures, resulting in high carbon dioxide emissions. Ulm and his team are looking for a different mineral to use in cement that would give it an equally strong nanostructure, but would not need as much heat.
Computer simulation of concrete's nanostructure, or its arrangement of atoms. image: Markus Buehler
"A small progress here in nanoscience and nanotechnology could actually have an enormous impact on global CO2 emission," says Ulm. "The strength of science and engineering, in particular nanoengineering, is that today we have the tools in place and the knowledge in order to tackle this, one of those most critical problems, which is CO2 emission and global warming on this planet."
Beyond reducing emissions, Ulm says such control over cement could result in new kinds of concrete, potentially leading to improved nuclear waste storage facilities, blast-proof tunnels, or longer lasting roads and bridges. But this nano-engineered cement is at least five years away.
Ulm's colleague Georgios Constantinides uses a nano-sized needle to look at
cement's nanostructure.
"Five years is a reasonable timeframe to come up with a concept material. The CO2 emission is not something which you can solve from one day to the other," says Ulm. "If you put those five years in perspective to the evolution of concrete which started with the Romans, five years is a pretty short time in mankind's history."
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