Materials

Bendable concrete goes cement-free to cut environmental footprint

Bendable concrete goes cement-...
The new bendable concrete is put to the test
The new bendable concrete is put to the test
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The new bendable concrete is put to the test
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The new bendable concrete is put to the test

Concrete is the world’s most widely-used building material thanks to its incredible strength – but it doesn’t stand up well against bending. Now, researchers at Swinburne University have developed a new type of concrete that can not only bend better, but doesn’t require cement to make, reducing its environmental footprint.

Put a huge weight on top of a pillar of concrete and the material will barely notice it’s there. But apply that force to the center of a pillar, and it will bend and break relatively quickly. This weakness is because concrete has high compressive strength but lower tensile strength.

In response to that, bendable concrete has been created and improved over the last few decades. And now, the Swinburne team has improved the recipe further, by reducing how much energy it takes to produce the material, as well as cutting carbon dioxide emissions during production.

The biggest polluter in concrete production is cement, the “glue” that holds the wet mixture together. Making cement requires high temperatures, so it gobbles up huge amounts of energy and churns out a lot of greenhouse gases. And as useful as bendable concrete is, it still involves this process.

But the newly-developed concrete ditches cement entirely. Instead, it’s made using industrial waste products such as fly ash, the airborne debris given off in coal-fired power stations. This geopolymer composite, as it’s known, can be cured at room temperature, so it’s far more environmentally friendly to make.

This alternative process has been used to make regular concrete in the past, but the team says this is the first time it’s been used in bendable concrete. The resulting product cuts energy consumption and greenhouse gas emissions during production, while being far more bendable than standard concrete.

“Production of this novel concrete requires about 36 per cent less energy and emits up to 76 per cent less carbon dioxide as compared to conventional bendable concrete made of cement,” says Behzad Nematollahi, corresponding author of the study. “Our laboratory test results showed that this novel concrete is about 400 times more bendable than normal concrete, yet has similar strength.”

And even when the new material finally does crack, tiny polymeric fibers in the mixture make sure that it doesn't shatter. Instead, it will continue to hold strong under tension with multiple tiny fractures. The team says that this bendable concrete could, for example, be used in earthquake-prone areas for buildings that can withstand regular shakes without weakening. Cutting its carbon footprint should help make this more viable.

The research was published in the journal Construction and Building Materials. The bendable concrete is put to the test in the video below.

Bendable cement-free concrete

Source: Swinburne University

15 comments
Fairly Reasoner
Fly ash concrete is hardly new. And the top US coal fired generating stations DO run clean, despite what we're wanted to believe.
aki009
Cool stuff, but fly ash? Have these guys put a Geiger counter next to one of their panels? While it's not a big deal for outdoor infrastructure, I wouldn't want that stuff in my home.
Worzel
I can imagine, a 40 storey high-rise, swaying gently in the wind, like a tree on a summer afternoon. Reducing power usage is good, reducing CO2, not! The planet needs far more of it.
Pradeepsai Lokanadham
Blaming cement a big polluter ....... I want to know where do the Fly ash & coal fired airborne material comes from ... equivalently this is also polluter
MSDT
aki009 Fly ash is not radioactive to any significant level(Ignore the headline-read the article). https://www.scientificamerican.com/article/coal-ash-is-more-radioactive-than-nuclear-waste/
Aross
Lots of negatives so far. I am interested to know how this would fare in colder climates. Concrete tends to crack and crumble when subjected to frost heave. Bendable concrete sounds like an answer to this problem.
1stClassOPP
Ahhh, new road surfaces maybe?
Karmudjun
@Fairly Reasoner - You are absolutely right, Flyl Ash is a very well known pollutant for decades. But Fly Ash concrete without cement as the binder? NEW!!!!!!!!!!!!!!!!!! @Worzel - Where did you get your agricultural degree? We do NOT need more CO2 in our environment. While all photosynthesis uses CO2 (to the best of MY knowledge), the efficiency of chloroplasts is so high as to pull enough CO2 out of the air for continued existence without needing levels high enough to induce the greenhouse effect. That goes for Methane, Halogenated Anesthetic Gases, and other worst greenhouse man-made molecules. I'd like to read one or two of the studies you base your "reducing , not!" statement upon. And in the 1970's, I was in a 36 story steel and glass structure that still does sway in the winds - you would not want to be on the 40th floor of a structure that swayed more than that tower swayed. I don't get seasick but several workers did get seasick and have to go to lower floors because of the movement. If you don't get my point, nature's technological efficiency means we absolutely do not need to acidify our oceans and pump more CO2 into the air for any reason other than to destroy our environment for future generations.
GordonHoffman
So, is this similar to the geopolymer concrete that was mentioned as a building material to be used for constructing structures floating homes - from an article about the Seasteading Institute. It has been elusive to find some of this stuff to buy and use at home.
Gregg Eshelman
I'd call this concrete with a non-catastrophic failure mode, instead of bendable. Bendable implies that it should return to original shape with little or no loss of its structural properties, or will at least return to its original shape. We briefly see at the end of the video that it doesn't, as the ram rises off the still deflected slab. A structure built with this stuff would hang together considerably better during an earthquake, but it'd still be destroyed - and would be far harder to demolish to make way for rebuilding. Then there's the problem of recycling. Concrete is one of the most recycled materials, up there with metals and asphalt paving. Much of the sand and small aggregate content in concrete is produced by crushing old concrete from demolished structures. You don't see that in the bags of concrete mix you get at Home Depot or Lowes, because people expect 'shiny new' gravel in their bags of concrete.