Roman concrete

[Kitty Von Catsworth]

So scientists are just learning how the ancient romans mixed concrete  ,lol.   Apparently it is far better ,stronger and longer lasting than todays  .  

http://www.bbc.com/news/science-environment-40494248

[Mister Obvious]

The concrete gains strength from the exposure rather than eroding...

That's really brilliant. It reminds me of a theory I developed about the Japanese (I believe) making products out of self-mending materials. When they get damaged, they use heat etc. to 'bind' back together.