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Old tires make for stronger concrete

Old tires make for stronger co...
Civil engineering postdoctoral researcher Obinna Onuaguluchi tests the reinforced concrete
Civil engineering postdoctoral researcher Obinna Onuaguluchi tests the reinforced concrete
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Some of the polymer fibers obtained from shredded tires
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Some of the polymer fibers obtained from shredded tires
Civil engineering postdoctoral researcher Obinna Onuaguluchi tests the reinforced concrete
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Civil engineering postdoctoral researcher Obinna Onuaguluchi tests the reinforced concrete

For some time now, crumbs of rubber from ground-up discarded tires have been used to produce a more resilient form of asphalt. Researchers from the University of British Columbia are taking things in a different direction, however, by using polymer fibers obtained from old tires to make concrete stronger.

Added to existing concrete (which is a mixture of cement, sand and water), the stretchy fibers bridge tiny cracks as they form, keeping them from becoming bigger. In lab tests, concrete with the added fibers was found to be over 90 percent more resistant to problematic cracks, as compared to conventional concrete.

What's more, the fibers only need to make up 0.35 percent of the total mixture.

Some of the polymer fibers obtained from shredded tires
Some of the polymer fibers obtained from shredded tires

Not only could the technology help keep tires from ending up in landfills, but it should also reduce the number of times that concrete structures have to be replaced. Given that cement production is a major source of carbon dioxide, the less often the material has to be used, the better for lessening the emission of greenhouse gases.

Led by civil engineering professor Nemkumar Banthia, researchers used the fiber-reinforced concrete to resurface the steps of UBC's McMillan building last month. Utilizing sensors embedded in the concrete, they are now monitoring it for factors such as strain and cracking – so far, the results are promising.

A paper on the project was recently published in the journal Materials and Structures.

Source: University of British Columbia

9 comments
Oun Kwon
What a refreshing news! Good for them.
VincentWolf
Why can't they just make it more like 10% rubber so we get some impact resistance built in as well (flexibility, grip, etc)?
SzMike
It might be because of other factors, like thermal expansion.
Bruce H. Anderson
Larger fibers are in current use to prevent cracking. This looks like another source has become available, and it also removes product from the waste stream. I wish them well.
christopher
Fire?
DouglasAnkrum
..Good deal...I used to work as a welder/mechanic for a company that built the tire shredders, a lot of engineering went into getting more useful products out of the old tires. the most useful rubber came from the tread area, sidewalls were considered 'scrap' due to the fabric embedded in the rubber, steel wire from the bead was also recycled..still, only about 30% of the tire was reclaimed. Hopefully this process will help, otherwise the tires just go to 'storage' in landfills where they pretty much never break-rown....
Rob Tillaart
Although it sounds good for the recycling of old tires, I wonder if the rubber downgrades the ability to recycle the concrete after its economic life. ( 30-100++ years?) Does the rubber has the same life expectancy as concrete? What will happen with the strength and structure of the concrete when the rubber breaks down after 10, 20,30,.. years?
JimFox
"downgrades the ability to recycle the concrete after its economic life. ( 30-100++ years?) Does the rubber has the same life expectancy as concrete? What will happen with the strength and structure of the concrete when the rubber breaks down after 10, 20,30,.. years?" It's NOT rubber but polymer fibres! You should work on your reading skills, Rob. Various fibres have been used concrete/cement strengthening for many years including thin HS steel needles and glass fibre. Like any reinforcement, concrete cover is essential if it subject to degradation. In Australia I bought acoustic flooring underlay made from old tyres that were 'crumbed' then heated/rolled into sheet form.
Bob Stuart
I remember the first test of asphalt with rubber breaking up rather quickly on Douglas St. @ Crystal Gardens. I hope it is better now, not just unadvertised. Adding fiber to concrete is well known to work at any scale; rebar is just the cheapest format for labour.