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By Jeff Wing
November 28, 2016
Bricks and mortar. Steel. Glass. Wood. Buildings have been made of the same stuff for about 5,000 years. It could be said that the last great construction materials disruption occurred around 1800 B.C., when it was inadvertently discovered that mixing iron with carbon at high temperatures produced a new hybrid metal with amazing qualities of strength and resilience. It came to be called steel, and it changed the world. Nowadays, the engineering and materials breakthroughs are happening at the molecular level, breakthroughs which are poised to remake our culture. Nanotech may just be the new steel.
The construction industry is keeping a keen eye on nanotechnology research, deeply engaged as that research is in what is called Materials Science; the building of customized new materials from the molecule up––materials that do exactly what you want them to. Nanotech is, after all, engineering. True, the objects being engineered are small—or more accurately; very, very, very small. Nanotech deals with objects that are measured in nanometers. For a sense of scale, consider that a human hair is about 90,000 nanometers thick. A Carbon Nanotube (one of nano-construction's tiny new building blocks) is 1 nanometer thick. One. Nanometer. Thick. Nanotech’s ability to fabricate materials at that very base level means re-engineering and tailoring materials at their very essence. Once perfected, this capability is going to change the way we live, the way we heal, and the way we build. Here are a few examples.
If the goal is “lightweight and super strong,” you could do worse than the Polymer Nanotruss, a nano structure whose implications for the construction sector are almost unimaginably vast. The tiny polymer nanotruss' geometry is based on the microstructures that comprise seashells, whose disproportionate lightness and strength have long fascinated researchers. In work being led by Caltech’s Dr. Julia Greer, the first polymer nanotruss was constructed by reverse-engineering the foundational molecular structure of the seashell.
Now researchers coat these tiny structures with various common materials––ceramic, in one notable instance––and then remove the underlying polymer framework. What is left behind is a new ceramic (in this instance), a ceramic that at the molecular level has taken on the structural advantages of the nanotruss that was its foundation. The finished “nano-ceramic” structure is actually 85% air, but is much less brittle than standard ceramic due to its new micro-structural strength. The nanotruss model suggests that forming nearly any kind of familiar compound around these hyper-efficient microstructures will lead to super-strong, super-lightweight building materials that could one day replace bricks and steel in our buildings.
Researchers found that when they experimentally etched a geometric microstructure pattern onto a steel plate, the steel was able to deflect or bend seismic wave activity away from a direct influence on the steel plate itself. The micro pattern, minutely etched into the surface of the steel plate and actually invisible to the naked eye, acted as a sort of baffle to buffer and redirect the energies of the elastic waves directed at the steel. The experiment has great implications for seismically active regions. When the micro pattern etching has been perfected and we are able to scale the etching process, the cladding (or skin) of a building could be made of one of these “metamaterials,” and the seismic shock wave event deflected by these minutely engraved micro patterns.
Concrete is so central to our built environment it’s impossible to imagine construction without it. But the uncomfortable fact is, the production of concrete is not a terribly green process. Concrete production is, in fact, the second highest pollutant-process in the world. Researchers have found that the introduction of cellulose nanocrystals to a concrete mixture overcomes the structural flaws inherent to concrete’s production, drawing water more thoroughly into the mix and allowing less concrete to do more with its added nano-strength. This has environmental implications, since less concrete would be needed to achieve the same structural effect. And the nano-additive, cellulose, is so commonly found, both in the plant world and as a byproduct of the paper and agriculture industries, this “nano-solution” does not require much energy to be spent in its curation.
Dr. James Tour of Rice University has been busy building cars for the past several decades. That might seem like a strange occupation for a synthetic chemist, until you learn that his cars are small—so small that 50,000 of them could have a nano-tailgate party around the diameter of a human hair. The wheels of these cars are actually individual molecules. What role could these nano cars play in construction? Hint: there is strength in numbers.
If 50,000 of these tiny cars can fit around the diameter of a human hair, think of how much work would get done if you flooded a project with invisible swarms of billions of these tiny cars, each with its individual task assignment. Dr. Tour posits just this kind of benevolent traffic jam being used for a new kind of construction; building with nano-machines. Rather than using the traditional building materials, you would provide the common raw materials of sugars and carbohydrates to power the nano-machines, and the base nanomaterials of the building itself. Buildings would begin as very light scaffolding comprised of cells which the nano-dragsters would fill with molecular building material. Hypothetically, if you were present at this nano-groundbreaking, you would soon perceive a building forming right there in front of you; not as bricks and steel being moved into position, but as swarms of programmed molecules being directed to individual and group tasks which in the aggregate would produce a building.
In this approaching new world, the tiny shall inherit the Earth. Or at least make it a better place to live. Nanotech research promises to bring very small but potent solutions to everything from construction to self-cleaning walls to spinal cord repair.
But is there any danger inherent to nano research? Dr. Tour corrected this misperception.
“Well, if the release is massive. Real nanobots do not self-reproduce, so it would have to be a massive release of a toxic material. But nano itself is no more toxic than organic chemicals, or inorganic chemicals. And there are a lot of safeguards in place, and studies. Unlike other newly explored fields in the past, the toxicology and environmental ramifications have been closely studied and watched from the very birth of the field.”
Good to know.
Construction may be overdue for a more introspective era. For years, global design firms have been competing to see whose enormous, ultra-modern building can reach the highest heights. It’s interesting to note that the future of construction may in fact be all about going small. Really, really, (really) small.
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