Coffeecrete? Coffee Grounds can make Concrete Stronger

[Brad]

Coffee grounds offer performance boost for concrete

https://techxplore.com/news/2023-08-coffee-grounds-boost-concrete.html

[littleman]

I wish they explained a bit more about how coffee grounds do this.  Maybe its the nitrogen?

During WWII the UK & Canada were considering making giant aircraft carriers made from ice and wood pulp, apparently adding wood pulp to ice makes it much stronger.

https://en.wikipedia.org/wiki/Project_Habakkuk