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Graphene Makes Concrete Twice As Strong While Reducing Carbon Emissions (inhabitat.com)
Paige.Bennett writes: In a recent study, University of Exeter's Center for Graphene Science used nanoengineering technology to add graphene to concrete production. The resulting graphene concrete is two times stronger than traditional concrete and four times as water resistant, but with a much smaller carbon footprint compared to the conventional process of making concrete. According to the research, the addition of graphene cuts back on the amount of materials needed in concrete production by nearly 50 percent and reduces carbon emissions by 446 kg per ton.
Bold claim considering CVD is the only viable way produce graphene.
CVD is not the only way to make graphene.
Graphene is currently way too expensive for a bulk product like concrete, but if a big market is available more research will go into mass production techniques. More research should go into reinforcing concrete with other substances as well. I have seen concrete reinforced with peat moss, coconut fibers, and shredded bamboo. These increase tensile strength, and shock absorption, but reduce compressive strength.
In tension, compression, or both? If tension this could be a big deal. Compression, meh, incremental improvement.
Of course, I'm not a structural engineer. But I did read a book called Structures; Why Things Don't Fall Down so I think I'm qualified.
Is graphene safe?
"We do not yet know whether graphene flakes can become airborne and inhaled in a form that is dangerous during use."
Are carbon nanotubes the next asbestos?
"The difference with asbestos was that the hazards were not known or ignored; large-scale use meant large-scale production, resulting in emissions that weren't properly controlled, which in turn caused exposure at unsafe levels and then widespread disease. This should never have happened and should never again happen."
How much does it cost? Because lots of things are stronger than concrete. Steel, for example is like 20 times stronger than concrete in compression and basically infinitely stronger in tension.
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As articles like that point out, they do know how.
It isn't used because it is more expensive. Simple.
This is even more expensive, and even better. So, even less useful.
From the article (I know, I know): ...The production of 1m3 of concrete requires ~ 360kg of cement (assuming 1:1.5:3 materials ratio, 0.45 w/c). Therefore the addition of 125g of graphene ($0.45 per gram [4]) can decrease the total volume of cement down to 148kg per 1m3. ...
OK, so now we know the actual ratio required for the stated benefit. One gram of graphene replaces about 1.7 kilograms of cement. [(360 - 148)kg / 125g]
At $0.45 per gram it is not yet cost competitive (here in the states anyway) but it is only about an order of magnitude off, which for an initial attempt in a new material is not that bad.
i have been a practicing structural engineer for well over thirty years. So we all understand, the bulk of concrete design is typically not controlled by the concrete design strength; because concrete failures are brittle (sudden) they are avoided. There are other admixtures/components currently in use that provide the other stated benefits. Consequently, cost will be, as usual, the determining factor in graphenes adoption.
-SET