Recycled coffee grounds make cement stronger, say scientists

Originally published at: Recycled coffee grounds make cement stronger, say scientists | Boing Boing


Probably better just to compost them.


i usually compost them, but with the amount we generate our compost seems like 30% coffee grounds. if i could give some so someplace that would use them for concrete projects, that would be great.


I can add a substantial ongoing supply of coffee grounds if anyone wants them.

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Now let’s figure out how to build things using lots of salt, and get busier with the desalination process in coastal areas.


Well, this sounds kind of useless to me. You can’t first use the grounds to make coffee, so we’d need to start farming even more coffee, or stop drinking it ourselves.

That’s not the way I read it. I think they are talking about used coffee, which is the more common meaning of “coffee grounds”.

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Concrete & coffee is actually a pretty good description of my first years as a civil engineer.

And in case anybody wonders, yes, the kind of sand needed to make good concrete isn’t just laying around everywhere. Composition, shape, grading curve, and so on, it really matters. Saudi Arabia, for instance, has to import it. There are places with black markets for sand, sand robberies, people making off with whole sandbanks.


Sandbank robbery

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Wow, salt and 5% something else for a brick! (And, not fired at the melting point of salt.) Huh. Better hopium than I use.


I’ve seen stuff about people trying to make the right sand. Brown glass is worthless except for making more brown glass when recycling. So, one of the options is to grind the glass down basically to sand, and in so doing, you can get the control over the shape and size that you need, mostly.

Plot point in a Carl Hiaasen book too.

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I’m very curious about what the expectations are for longer term chemical stability.

There are some bits and pieces (like this one) from archeologists fretting about charcoal missing from the archeological record in certain alkaline conditions that suggests some room for relevant interactions within the concrete; potentially even on a timeframe where it will become relevant within the expected service life.

I don’t doubt that this has been considered; and is probably already under review; but at a bare minimum replacing mostly-silicon-dioxide sand with pyrolyzed organic material isn’t going to make predicting what happens over the course of a few decades of service under various conditions any simpler.

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Almost certainly a ‘do not’ item at the ‘oh it has live cultures that come alive with water to cure any crack’ cement company. ( aka green basilisk. Probably others also.)

e.g. ‘Feed after midnight’ → concrete eats carbon fiber reinf. DO NOT.
‘Get it wet’ → Heals cracks
‘Feed Jimmy Johns in crack’ → concrete takes on pear-shaped finish. DO NOT.

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