r/science • u/mvea Professor | Medicine • Nov 03 '19

Chemistry Scientists replaced 40 percent of cement with rice husk cinder, limestone crushing waste, and silica sand, giving concrete a rubber-like quality, six to nine times more crack-resistant than regular concrete. It self-seals, replaces cement with plentiful waste products, and should be cheaper to use.

https://newatlas.com/materials/rubbery-crack-resistant-cement/
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u/the_original_Retro Nov 03 '19

I'd like to see how this stuff lines up though. Its nature has REALLY changed with these additions, and asphalt works so well because it has the flexibility that this stuff has.

Could be it's just as good as asphalt perhaps?

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u/leno95 Nov 03 '19

The biggest issue with concrete (assuming this is what you're referring to) is that with temperature differences moisture trapped inside after the concrete has cured can cause expansion and contraction due to the moisture freezing/warming up. This eventually leads to spalling and the surface eventually crumbles away.

As long as the concrete is used in an area where the temperature doesn't have dramatic changes over a year it shouldn't be too bad.

You could use additives to help with the weaknesses concrete has with temperature variations, but from a financial standpoint it is no longer cost effective. You'd just opt for asphalt/tarmac as an alternative, as they have similar properties at a far lower cost. Source: I'm an infrastructure quantity surveyor.

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u/Herbert-Quain Nov 03 '19

I think he was referring to the rubber rice concrete. Less cracks, due to being less brittle, and "self-sealing" sound promising...

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u/MerryChoppins Nov 03 '19 edited Nov 03 '19

You skipped the whole discussion about salt use in roadways and spalling. I live in a state where we don’t just spread salt, we also have scheduled brine spraying of bridges and overpasses on all interstates, state routes, TARP routes, etc to prevent accidents. The leeching induced spalling can sometimes be unreal.

Edit: leeching induced spalling due to corrosion of steel elements

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u/WazWaz Nov 03 '19

Asphalt is recyclable. Just as well though, since its main ingredient comes from the bottom of an oil refinery so we'll run out eventually, by necessity.