By Nick
Lavars
March 30, 2022
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Crumb rubber concrete made by grinding down discarded tires
has stood up well in real-world testing Photo credit: DepositphotosVIEW 1 IMAGES
The type of concrete at the center of this study is known
as crumb rubber concrete, and its production involves grinding rubber tire down
into crumbs of a similar consistency to sand. These crumbs can then be used to
replace a certain proportion of the sand typically mixed in with the cement,
water and other ingredients to form concrete, lessening the reliance on the
natural material and giving the discarded rubber a second life.
Scientists at the University of South Australia and
Melbourne's RMIT University have sought to take this material from the
"lab to the slab," noting that while it has shown a lot of promise in
laboratory testing, its reliability in real-world construction requires further
exploration.
To investigate its practical application in residential
settings, the scientists poured two crumb rubber-reinforced concrete slabs at
the University of South Australia campus in 2018, along with two conventional
concrete slabs. These formed the entrances to a civil engineering laboratory
that sees a lot of foot traffic, with the team closely monitoring the
materials' performance over time.
“We found that reinforced crumb rubber concrete (with up to
20 percent sand replacement by volume) is superior to conventional concrete in
some ways, with higher impact resistance, toughness and ductility, a higher
damping ratio, better thermal and acoustic insulation, and a lighter
weight," said study author Dr Osama Youssf. “With respect to pumping,
screeding, or finishing the concrete surface using a power trowel, contractors
also reported no difference between using the crumb rubber concrete and
conventional concrete, saying that the crumb rubber mix actually required less
physical effort across all aspects."
Factors like impact resistance and toughness bode well for
the longevity of the concrete, which is a key focus for scientists working in
this area. Concrete is incredibly carbon-intensive to make, so when it begins
to crack, degrade or fail and structures need to be replaced, it places yet
more strain on the environment. Making more durable forms of it while putting
old, non-biodegradable tires to use could therefore be beneficial on a couple
of fronts.
“The results clearly show that crumb rubber cement is a
viable and promising alternative to conventional concrete in the residential
concrete market,” said study author Professor Yan Zhuge. “We strongly recommend
that the concrete industry considers crumb rubber concrete as a sustainable
alternative to conventional concrete in reinforced residential constructions in
Australia.”
The research was published in the journal Structures.
Source: University of South Australia