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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.
In principle you are correct. In practice, from both a cost and feasibility point of view this makes zero sense in the context of the scale at play. Concrete is (by far) the most abundant synthetic material ever made: therefore, any, I mean any, material that is added would need to be cost competitive at the scale not of a few cm per minute, but tons per hour. None of the current processes actually are cost effective as they claim to be. In other words those folks in the paper show do due diligence before venturing into claims they cannot support.
What will it cost? If it costs 100 times as much per ton they might as well not waste their time. We hear about all these miracles but it seems they are decades, maybe a century, away from being practical. Well, maybe one day.
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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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