Materials

Next-gen reinforced concrete is said to be lighter and more eco-friendly

Next-gen reinforced concrete i...
Amir Hajiesmaeili tests the new material to the breaking point
Amir Hajiesmaeili tests the new material to the breaking point
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Amir Hajiesmaeili tests the new material to the breaking point
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Amir Hajiesmaeili tests the new material to the breaking point
The polyethylene fibers (left) as compared to currently-used steel fibers
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The polyethylene fibers (left) as compared to currently-used steel fibers
The new concrete is strength-tested
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The new concrete is strength-tested
A view inside the polyethylene-fiber concrete
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A view inside the polyethylene-fiber concrete

Concrete is a mixture of cement, an aggregate such as gravel, and water. For added strength, steel fibers are sometimes added. Now, scientists are claiming that a new type of fiber-reinforced concrete could soon serve as a lighter and greener alternative.

The experimental building material was developed by Amir Hajiesmaeili, a PhD student working in the Structural Maintenance and Safety Laboratory of Switzerland's EPFL research institute.

In place of the usual steel fibers, it incorporates fibers made of a very stiff type of polyethylene. These not only provide the same amount of structural support as steel fibers, but they also adhere very well to the cement. As a result, approximately half as much cement is required, with readily-available limestone making up the difference.

This is quite noteworthy, as the production of traditional Portland cement is a major source of greenhouse gas emissions. In fact, Hajiesmaeili claims that the manufacturing of his ultra high-performance fiber-reinforced concrete (UHPFRC) releases 60 to 70 percent less CO2 than that of regular steel-fiber equivalents. And as an added bonus, the material is also reportedly 10 percent lighter.

A view inside the polyethylene-fiber concrete
A view inside the polyethylene-fiber concrete

Plans now call for the new UHPFRC to see its first real-world application next year, when it will be used to reinforce a bridge. "With this material, we can add value to age-old structures by ensuring they will last for a long, long time," says lab leader Eugen Brühwiler. "This solution is also much more financially and environmentally sound than razing and rebuilding existing structures like bridges and historical monuments."

And for an even more eco-friendly approach, the EPFL concrete could conceivably be used along with a new polymer rebar developed at Australia's Deakin University, the production of which requires only one quarter as much energy as that of conventional steel rebar.

Source: EPFL

11 comments
Mzungu_Mkubwa
Now, combine these polymer reinforced technologies with 3-D printing advances to remodel our world!
Gannet
And CO2 free cement? Has New Atlas ever had a look at this ? https://tececo.com/simple.eco-cement.php
jps2705
Unless I've missed something this is not new. We were using ready mixed concrete with fibre filaments added to reduce rebar quantities and shrinkage cracking 10 years ago in South Africa.
Mik Fielding
Interesting but only if the polyethylene came from a recycled source as we really don't need to add more plastic into the environment! May as well use hemp fibre instead as that has been found to be an excellent addition.
McDesign
The use of PP fibers are decades old, and "metal fibers" are NEVER put into concrete - re-bar and re-wire, yes. Pre- or post-tensioned rods or cables, yes. I mean, I'm sure this is an advance, but I don't understand what it is.
HighlanderJuan
I suspect the whole 'too much CO2' greenhouse gas promotion is false. Greenhouses still have to use CO2 generators in order to help their plants grow. And, oh yeah, CO2 is not a toxic gas, as is CO. Hempcrete may still offer a better solution.
Douglas Rogers
Most of the fibered cement is still asbestos cement, as it was put on as asbestos shingles between 1920 and 1970. Asbestos is relatively cheap and has the right elastic modulus to make a two phase material when combined with cement. It bonds well to the cement. Glass fibered cement has been used to replace asbestos. Glass rebar is used in salt water applications. Graphite works well, as it can have the same modulus as steel and asbestos but it is much more expensive.
Signguy
As others have indicatated, HEMPCRETE BEATS THEM ALL. Stop trying to reinvent the wheel!
Eric Blenheim
So the plants will have less CO2 to feed on, less plants, less oxygen for us all to breathe, less oxygen, less mental capacity, more cancer and disease. And CO2 has been debunked as a cause of global warming now, with Russian scientists having been saying for years that we are in fact heading into a mini ice age, and the science bears that out with global temperatures actually dropping now, not rising. Besides, atmospheric CO2 levels have never had any influence on global temperature in past centuries, and the gradually changing relative positions between the Sun and Earth in varying orbital cycles are what are really responsible for changing global temperatures. I don't think that stuff will really be very green when future generations find asbestos-like deposits of the plastic fibres in the soil when this 'concrete' breaks down. I am all for materials being used that really are green in how they eventually do eventually break down. Roman concrete structures from 2,000 year ago still exist, but they used a different method of production, using sea water to produce such resilience, and their concrete does not eventually break down to leave nasty sharp plastic fibres in the ground. See; 'Scientist believes she’s found the recipe for ancient Roman concrete used 2,000 years ago'. Also; 'Mystery of 2,000-year-old Roman concrete solved by scientists'.
Diane Baggett
Yes in the old days we did use metal fibers in concrete, we are currently using fiberglass.