Graphene replaces sand to make lighter, stronger concrete

Graphene replaces sand to make lighter, stronger concrete
A new study swaps sand for graphene to make lighter, more environmentally friendly concrete
A new study swaps sand for graphene to make lighter, more environmentally friendly concrete
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A new study swaps sand for graphene to make lighter, more environmentally friendly concrete
A new study swaps sand for graphene to make lighter, more environmentally friendly concrete

When you think of resources we’re running out of, sand might not be high on your list, but it’s up there thanks to our high demand for concrete. Scientists at Rice University have now shown that substituting graphene can not only save sand, but makes concrete lighter, stronger and tougher.

Despite being a sheet of carbon atoms just one atom thick, graphene has a reputation for being incredibly strong. As such, it’s no surprise that this 'wonder material' has been mixed into concrete before, usually to make it stronger and more durable. But that usually involves just adding graphene to the recipe – for the new study, the Rice team wanted to replace sand completely.

Concrete is made of three main ingredients: water, an aggregate like sand, and cement to bind it all together. Sand is the largest component by volume, and given modern humanity’s insatiable appetite for concrete, sand mining is increasing. Not only is this process destructive, but it risks running out of sources.

The research comes from the lab of Rice University chemist James Tour, whose team has been making graphene for years using a technique they developed called flash Joule heating. Essentially, a carbon-rich base material is quickly superheated with a zap of electricity, converting it into graphene flakes. In this case, the base material was metallurgical coke, a fuel source created from coal.

“Initial experiments where metallurgical coke was converted into graphene resulted in a material that appeared similar in size to sand,” said Paul Advincula, lead author of the study. “We decided to explore the use of metallurgical coke-derived graphene as a total replacement for sand in concrete, and our findings show that it would work really well.”

Saving sand wasn’t the only benefit, either. The resulting concrete was 25% lighter than concrete made with a normal aggregate, and showed a 32% increase in toughness, 33% in peak strain, and 21% in compressive strength. On the down side, there was an 11% reduction in its Young’s modulus, a measure of a material’s resistance to deformation by stretching.

While the team says graphene is currently too expensive to make this method commercially viable at scale, it at least shows that there are alternatives that could be pursued.

The research was published in the journal ACS Applied Materials.

Source: Rice University

This needs a full life cycle analysis. Replacing sand with graphene may well yield more robust concrete but there are also issues around supplying fossil fuel/coal to make the graphene, and the energy required. And what happens after the building is demolished? Yes, it shows that there are options, but let's see something much more robust in terms of analysis.
Yes, Graphene is too expensive. Well, they knew this from the start! Also the quantity required makes it an impossible project.
There is plenty of sand in the Sahara, but apparently it is the 'wrong type'.
Sheesh! Let's see, regular sand used in concrete is 80% silicon dioxide (silica sand) and 20% this and that. The two most common elements in the Earth's crust are -- wait for it -- Oxygen (46%) and Silicon (28%). Note the not-actually-a-coincidence in the percentages -- the overwhelmingly prevalent combination of the two is in SiO_2. The prevalence of Carbon is -- wait for it -- 0.02%. In the form of coal, it is difficult, expensive, and dirty to mine. There are a mere handful of actual graphite mines, and their output is almost completely consumed by several industries as graphite is a key component of batteries and we're trying to electrify basically all transportation.

Graphene costs somewhere in the range of $20 to $2000 per kilogram. Sand costs around $0.01 per kilogram.

Replacing sand with diamond, or aluminum oxide, would probably make for stronger and/or lighter concrete as well, but this is straight up no brainer stupid.
Will graphene replace microplastics as a future health threat? Will it be shown to come loose from concrete or other "new, improved!" and become a deadly carcinogen or other health hazard? Asbestos was a wonder material in its heyday (also added to concrete to make it stronger and lighter), and now it's an expensive hazwaste problem.
No mention of how well it would recycle. Will it just be dumped into landfill like old used concrete.
Along with the 11% reduction in Young's Modulus is the caveat "While the team says graphene is currently too expensive to make this method commercially viable at scale, it at least shows that there are alternatives that could be pursued."

So we have a proof of concept that cannot be feasibly produced for real world studies, for recycling, or for any other hair-brained commenter's recommendations. Maybe someone should contact Elon Musk and let him consider this material for his Rocket Launch pads - he has the money and the quirkiness to run with this type of research!
Instead of using graphene, why not just adopt the formulation that the Romans used? Their structures went up two millennia ago and are still standing. No need to get fancy. Just learn from history!
Gene Preston
I wonder if old wind generator blades could be ground up into a sand like mixture and made into concrete also? What about grinding up old concrete? A giant hammer could pound the stuff into a sand like texture. The article just opens up our imaginations about what we could use to make concrete like structures.
@rgbatduke, you really need to read up on the "sand crisis." Just because there's sand everywhere doesn't mean it's usable. Desert sand can't be used in concrete because the grains are too smooth, and no, there's no way to roughen it up.

As for all the naysayers who say this process is too expensive so it shouldn't be researched, remember the story of aluminum. Once upon a time, very hard to refine, so it cost something like 60x what it does today. Then somebody figured out an economical process and today it's one of the most commonly used metals in the world. Graphene is still new. It wasn't even isolated until 20 years ago. For all you know, somebody may figure out a way to synthesize it in bulk from atmospheric carbon dioxide, making it an ideal carbon sequestration method and killing two birds with one stone.
The people at Rice who have been using the Flash Joule Heating process to turn waste plastic into graphene and hydrogen at a 70% efficiency say that the graphene can be produced at 5% of its current market price without even considering the value of the hydrogen produced, so maybe, with all the waste plastic in the world, we'll see a crash in the price of graphene, making this cement more of a possibility.
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