Materials

Graphene made from old tires helps strengthen concrete

Graphene made from old tires h...
Researchers have found a new way to convert old tires into graphene and then use it to reinforce concrete
Researchers have found a new way to convert old tires into graphene and then use it to reinforce concrete
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Researchers have found a new way to convert old tires into graphene and then use it to reinforce concrete
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Researchers have found a new way to convert old tires into graphene and then use it to reinforce concrete
A diagram demonstrating how graphene can be produced through flash Joule heating
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A diagram demonstrating how graphene can be produced through flash Joule heating
This microscope image shows how the layers of this turbostratic graphene don't line up properly
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This microscope image shows how the layers of this turbostratic graphene don't line up properly
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Researchers at Rice University have developed a new process to convert old tires into graphene, which can then be used to make concrete. Not only is it more environmentally friendly, but the team says the resulting concrete is substantially stronger.

The research builds on the team’s previous breakthroughs in making graphene through a process called flash Joule heating. Essentially, this involves using a jolt of electricity to quickly superheat almost any carbon source to around 2,725 °C (4,940 °F), converting it into graphene flakes. Specifically, it’s a form of the material known as turbostratic graphene, which has layers that don’t line up perfectly. That makes it more soluble, and easier to integrate into composite materials.

This microscope image shows how the layers of this turbostratic graphene don't line up properly
This microscope image shows how the layers of this turbostratic graphene don't line up properly

Last year the team demonstrated the technique using waste products like food or plastic – and now, they’ve moved onto discarded tires. The Rice team says that previous efforts to convert tires directly into graphene didn’t yield the best results, so for the new study they turned to the material left over after they’ve undergone a common recycling process.

Pyrolysis involves burning tires in a low-oxygen environment, which creates an oil that’s very useful for a range of industrial processes. But it also produces a solid carbon residue that’s been harder to find new life for.

The Rice researchers found that this tire-derived carbon black was a great candidate for producing flash graphene. When they put the material through flash Joule heating, some 70 percent of it was converted into graphene, while a mixture of shredded tire rubber and commercial carbon black yielded around 47 percent.

Next, the team demonstrated a particular use case for the new graphene material – concrete production. They added 0.1 weight/percent (wt%) for the graphene produced from tire carbon black, and 0.05 wt% for the mixture of carbon black and shredded rubber into Portland cement. They found that concrete cylinders made with this cement showed around 30 percent better compressive strength than concrete made without the graphene additive.

“This increase in strength is in part due to a seeding effect of 2D graphene for better growth of cement hydrate products, and in part due to a reinforcing effect at later stages,” says Rouzbeh Shahsavari, co-lead author of the study.

A diagram demonstrating how graphene can be produced through flash Joule heating
A diagram demonstrating how graphene can be produced through flash Joule heating

The team says that the graphene-reinforced concrete has several environmental benefits. Not only could it help prevent waste tires from ending up in landfill, but the extra strength of the final material could reduce the amount of concrete needed in structures.

“Concrete is the most-produced material in the world, and simply making it produces as much as 9 percent of the world’s carbon dioxide emissions,” says James Tour, co-lead author of the study. “If we can use less concrete in our roads, buildings and bridges, we can eliminate some of the emissions at the very start.”

The research was published in the journal Carbon.

Source: Rice University

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4 comments
4 comments
VincentWolf
Better yet just use the tires themselves to form a roadway and pour over it a leveling fluid made of rubber. Nice squishy ride!
Username
If the process produced graphene then that graphene could be used for any graphene application. If the process produces some form of carbon material that is not quite graphene then it should not be called graphene. From what I understand, the most pressing concern with concrete is it's production environment impact and that we are running out of usable sand.
Karmudjun
Amazing use for TURBOSTRATIC FLASH GRAPHENE, given the positive improvement in compressive strength, it is certainly too soon to suggest all concrete production could be reduced by any percentage. Let the engineers and scientists with long term construction experience run durability tests before claiming pie-in-the-sky outcomes of this newfound usage of the left-over tire black. By the way Michael, did anyone happen to mention how much electricity was used to produce enough Turbostratic Flash Graphene to mix with one yard of concrete? It all factors into the environmental cost equations.
toni24
I have read a few articles which link graphene to cancer and other health risks once loose in the environment. I sure hope that this form does not have that property. That being said, why not employ basalt fibers in the concrete for strength. They are easy to produce and, so far, have shown no health problems that are not also a part of the health problems of fiberglass