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Okay, so I've noticed that a lot of people grind coffee, and a lot of companies grind it on an industrial scale.

Having produced some of the drink we called coffee, a huge proportion of the mass of the beans is simply thrown away, discarded. It's biodegradable, at least, but it's still waste.

Could coffee grounds, dried out and compressed, be used as a building material?

If it can, it would have these benefits:

  • A building material from a wasted resource
  • The source material is plentiful, it's everywhere.
  • No additional mining or agriculture would be required to produce it.
  • Like wooden housing, it would bio-degrade if left abandoned. So it's a low environmental impact.

Questions on this topic:

  • Can it be done?
  • What challenges would it present?
  • What practical issues are keeping this from happening?
  • What would it be like living in a coffee house?
  • Well, I am drinking about one brick's worth of coffee a year. If I continue doing that for the next 1000 years, or so, I will have enough bricks to make half a wall... –  Jun 03 '16 at 11:22
  • @CuriousOne possibly, but how about your average Starbucks? Or the factories manufacturing instant coffee? –  Jun 03 '16 at 11:34
  • You can buy about five brand new bricks for the price of one latte and ten used ones. :-) –  Jun 03 '16 at 12:35
  • @CuriousOne You might have a point there http://www.wickes.co.uk/Products/Building-Materials/Bricks%2C-Blocks+Lintels/Bricks/Engineering-Bricks/c/1001107 Perhaps I should give up coffee and build a house. –  Jun 03 '16 at 12:38
  • Interesting, but not a physics question, I think. – sammy gerbil Jun 03 '16 at 13:20
  • How do you feel about bio-degradable bricks? My coffee grounds (and some I pick up from Starbuck's, since they give them away for free) go into my compost heaps. –  Jun 03 '16 at 17:10
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    The *worldwide* production of coffee is about 8 billion kg per year, The *UK* alone produces about 7 billion kg of clay/sand bricks, and the US over 30 billion kg, even though the US makes much more use of wood as a structural building material than the UK, Add in the rest of the world, and the adjective "plentiful" doesn't seem quite right here. – alephzero Jun 03 '16 at 23:12
  • You answered your own question. Coffee grounds are biodegradable. Bricks made out of sand and clay are not. – user16622 Jun 03 '16 at 15:56

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Bricks are primarily made of sand and clay. The sand acts as a filler, and clay is a substance that has some rather remarkable qualities. Coffee grounds do not exhibit the qualities of sand or clay.

That said, people have suggested using coffee grounds to improve various qualities of bricks. Coffee grounds exhibit one quality that neither sand nor clay possess: Coffee grounds burn. The coffee grounds in a brick made with a mix of sand, clay, coffee grounds, and lime will burn upon being fired, thereby increasing the porosity of the fired brick.

Since coffee grounds burn (they burn quite nicely, better than wood), another use for spent coffee grounds is artificial logs for fireplaces.


References:

P. Muñoz Velasco, et al., "Eco-fired clay bricks made by adding spent coffee grounds: a sustainable way to improve buildings insulation," Materials and Structures 49.1-2 (2016): 641-650.

Rodney K. Sprules, "Coffee-based solid fuel composition", US patent 5910454 A.

David Hammen
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