Posts Tagged ‘concrete’

Photo: Evan Qu/Unsplash.
Self-healing concrete at the Pantheon in Rome.

I grew up in a family that placed high value on the humanities — the arts, literature — and the people who practiced them. With the exception of our beloved Uncle Jim, who was a chemist, and Margaret Lawrence, who was a physician, we didn’t know how to admire people who didn’t fit our limited definition of “creative.”

But today, I’m bowled over by the imaginative pragmatism of people who invent solutions to real-world problems like those who reengineer gasoline engines to use electricity, for example, or who invent building materials that reduce the dangerous carbon dioxide we pump into the atmosphere.

I think even my parents would have loved that today’s scientists are finding inspiration in the ancients. After all, it was fine to admire archaeologists.

Adele Peters reports at Fast Company on research that suggests new possibilities for ancient wisdom.

“A road or bridge made from modern concrete might only last 50 years. But the massive Pantheon building in Rome, made from unreinforced concrete, has been standing for nearly two millennia. And nearby, some ancient concrete aqueducts still deliver water to the city. What made ancient Roman concrete so much more durable?

“A new study from researchers at MIT and Harvard University, along with labs in Italy and Switzerland, suggests that an ancient manufacturing technique can create self-healing concrete that naturally fills in cracks. Using a similar process now could help shrink concrete’s massive carbon footprint. ‘We’re looking to the ancient world as a source of inspiration,’ says chemist Admir Masic, an engineering professor at MIT who focuses on sustainable construction materials.

“Cement, the glue that binds concrete together, is responsible for up to 8% of global emissions when it’s made, both because of the energy it uses and the process of heating up limestone, a key ingredient in the material, which releases CO2 directly. Multiple startups are now working on alternatives: including companies that replace limestone with different rocks or add captured CO2 to the final product.

“The Roman-inspired approach is different. By making concrete last much longer, far less of it would need to be made in the first place. … The older production method also happens at a lower temperature, so it uses less energy.

“The researchers studied samples from a 2,000-year-old city wall in an Italian city. They focused on tiny white fragments of lime that aren’t found in modern concrete, but are ubiquitous in old ruins throughout the former Roman Empire. …

“In the past, some researchers thought that the fragments, called lime clasts, were the result of sloppy mixing. But it’s more likely that they were formed deliberately, and the study suggests that they are the reason the concrete lasts so long.

When tiny cracks form in the concrete, water travels to the lime clasts, which dissolve and then fill the cracks with calcium carbonate.

“The researchers attempted to duplicate the manufacturing process that created the lime clasts, and then tested the material against samples made with modern techniques. After cracking the samples and adding rainwater, they watched what happened: The old-school concrete healed itself within two weeks, while in the modern version, the cracks remained.

“Other approaches to ‘self-healing’ concrete also exist now. For example, it’s possible to embed bacteria in concrete that can fill cracks; but it’s costly to make. ‘Current self-healing concretes are very expensive because they are based on very complex chemistry, while our material is super cheap,’ Masic says. … The ancient process involves adding quicklime, a calcium oxide-based material (also known as lime), directly to other ingredients before adding water.

“A new startup is now spinning out from the research to bring the concrete to market. It may later add other features that the lab is studying, including making concrete that can absorb CO2 as it sits outside.” That would be amazing!

More at Fast Company, here.

Speaking of “creative,” check out the varied interests of that MIT chemistry professor: “Professor Masic’s research focuses on the science-enabled engineering of sustainable construction materials for large-scale infrastructure innovation. A chemist by training, with expertise in biomineralization, he specializes in the development of multifunctional cement-based materials, ranging from self-healing concrete materials to carbon absorbing concretes and electron conducting cement-based materials.

“He is a principal investigator in the Concrete Sustainability Hub at MIT, a faculty fellow in Archaeological Materials at MIT’s Center for Materials Research in Archaeology and Ethnology (CMRAE), and the faculty director of the Refugee ACTion Hub (ReACT) at MIT. MIT ReACT aims at providing new professional content development for displaced learners around the world.”

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Photo: Houben/Van Mierlo architecten
New homes in the Netherlands are being created with a 3-D printer. 

Now for something completely different: how those creative Dutch are using 3-D printers to create homes.

Gianluca Mezzofiore reports at CNN, “Living in a community of 3D-printed homes will soon be reality in the Dutch city of Eindhoven.

“In what is considered a world first, a single-floor, three-room house made of 3D-printed concrete will be ready for occupation in 2019. More than 20 people have already registered their interest in the house since Dutch construction company Van Wijnen announced the project. …

” ‘We need a technical revolution in the constructing area to respond to the shortage of skilled bricklayers in the Netherlands and all over the world,’ Rudy van Gurp, a manager at Van Wijnen, told CNN. ‘3D printing makes things quicker, better, cheaper and more sustainable by using less material. It also fosters creativity and freedom in the design.’

“Working along with the Eindhoven University of Technology, the construction firm is printing a special type of concrete for the house’s exterior and inner walls by adding layer upon layer.

In laying concrete only where it is needed, the amount of cement being used is significantly lower, which helps cut down on costs and environmentally destructive carbon-dioxide emissions. Van Gurp estimates that 3D-printed walls of the new houses will be 5 centimeters thick, while normally they would be about 10 to 15 centimeters. …

“At the moment, research costs and regulation restraints outweigh the benefits of 3D houses, but we may see mass production of these in the next few years, van Gurp said.”

For more pictures and details, go to CNN, here.

Photo: Houben/Van Mierlo architecten
A 3-D printer lays down layer upon layer of concrete for a new home.



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Who can resist a playful idea, especially one that comes from civil engineers, a cohort perhaps given too little credit for creativity.

Corey Kilgannon writes in the NY Times, that a beloved pastime among civil engineers is racing concrete canoes.

“It might sound like an idea that would go over like the proverbial lead balloon, but in September, a group of engineering students at City College of New York began meeting and devising a way to build a concrete canoe.

“ ‘When I heard that, my response was like: “What? A boat made of concrete?” ‘ said Dr. Friso Postma, an expert paddler from Brooklyn, who had not heard of such a thing until he was asked to coach the team this spring, once the canoe was finished.

“Team members reassured him that while they were building the canoe over the winter, in a workshop at City College, they had made certain that the vessel would float. After all, they told Mr. Postma, the primary rule in concrete canoe competitions — yes, there are such events — is paddling a boat that does not sink.

“They also told him that concrete canoeing has a rich tradition among civil engineers, and at City College, whose teams go back to at least the 1970s.

“ ‘It’s a huge thing within the civil engineering program,’ said Juan-Carlos Quintana, 29, a team member. ‘We take it very seriously.’ ”

More here.

Photo: Kirsten Luce for the New York Times
Esther Dornhelm, left, and Fidan Mamedova practice at Paerdegat Basin in Brooklyn for this weekend’s national concrete canoe championships.

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The concrete that the ancient Romans created is so durable that it may hold lessons for those who want to reduce carbon emissions.

Paul Preuss, from the Lawrence Berkeley National Laboratory, explains.

“The chemical secrets of a concrete Roman breakwater that has spent the last 2,000 years submerged in the Mediterranean Sea have been uncovered by an international team of researchers led by Paulo Monteiro of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), a professor of civil and environmental engineering at the University of California, Berkeley.

“Analysis of samples provided by team member Marie Jackson pinpointed why the best Roman concrete was superior to most modern concrete in durability, why its manufacture was less environmentally damaging – and how these improvements could be adopted in the modern world.

“ ‘It’s not that modern concrete isn’t good – it’s so good we use 19 billion tons of it a year,’ says Monteiro. ‘The problem is that manufacturing Portland cement accounts for seven percent of the carbon dioxide that industry puts into the air.’ …

“The Romans made concrete by mixing lime and volcanic rock. For underwater structures, lime and volcanic ash were mixed to form mortar, and this mortar and volcanic tuff were packed into wooden forms. The seawater instantly triggered a hot chemical reaction. The lime was hydrated – incorporating water molecules into its structure – and reacted with the ash to cement the whole mixture together.”

Apparently the key ingredients are found all over the world, enough to make a big difference in construction — and carbon emissions.

There’s more at the Berkeley Lab site for readers who can follow a technical explanation.

Photo: Berkeley Lab

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