Posted May 21, 2022, 3:30 PM
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Join Date: Jun 2020
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This article in The Economist isn't about Winnipeg Roads, but it is relevant to the future of road building here. The article is about graphene, which has all sorts of interesting and useful material properties, but has so far been difficult to commercialize. However, it's first big application seems set to be as an additive to road materials.
I snipped out the most relevant ~20% of the article. The rest can be found here: The wonder material graphene may have found its killer app
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Graphene, which consists of monolayers of carbon atoms bonded in a repeating hexagonal pattern, is the thinnest known material. It was isolated in 2004 at the University of Manchester by Andre Geim and Konstantin Novoselov, who went on to win a Nobel prize for their discovery.
At the time, amid much hype, graphene was said to offer astonishing possibilities. It certainly has many interesting properties. For a start, it is 200 times stronger than steel. Yet it is extremely lightweight and flexible. It is also an excellent conductor of heat and electricity, and exhibits interesting light-absorbing abilities. Recently, for example, it has been shown that by arranging several sheets of graphene at particular angles, a superconducting version of the material (that is, one which lets electricity pass without resistance) can be created.
Yet despite this promise, apart from a few niche uses in electronics, water filtration and some specialist sports equipment, graphene remains largely unemployed. Certainly, no killer application of the sort predicted when the stuff was discovered has emerged. But that could be about to change. Concrete is as far from superconductivity on the technological sexiness spectrum as it is possible to get.
That does, indeed, sound like a killer app. There is, though, some way to go. As with most new materials it can take years for commercial production to scale up to the point of mass-market adoption. Petroleum-based carbon-fibre composites were invented in the 1950s, but it took more than 30 years before they began to be used in significant quantities in aircraft and cars. Graphene is now moving in that direction.
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One mixture in which Dr Tour is particularly interested in is concrete, some 30bn tonnes of which are poured every year. The addition of a small amount of graphene to concrete provides an anchor for the cement in it to grab onto, resulting in a more powerful interaction as the concrete cures. This means not only that less concrete is needed to achieve the same level of strength, but also that structures made of it are likely to last longer. Graphene-enhancement would also protect rebar, the steel rods used to reinforce concrete, from moisture. If water creeps into tiny cracks in concrete it can cause rebar to rust and expand, which results in concrete crumbling and sometimes in buildings collapsing.
In certain cases, indeed, the use of rebar in construction might be avoided altogether, saving costs and the emissions involved in producing the steel from which it is made. Last year, a team from the University of Manchester, working with Nationwide Engineering, a British construction company, used graphene to enhance the concrete floor of a new gymnasium in Amesbury, in southern England, avoiding the need for rebar. This reduced the amount of material that would otherwise be required by nearly a third, resulting in a similar saving in CO2 emissions.
Another hazard to concrete is chlorine, which is found in seawater and is particularly corrosive. [Graphene manufacturer] Sixth Element says it has found the addition of just 0.005% of graphene to marine cement enhances its resistance to chlorine by 40%.
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Other potential markets include adding small amounts of graphene to the bitumen used to make asphalt roads. This would greatly prolong their life, preventing creeping and rutting in hot weather and cracking during cold spells, which leads to potholes.
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