Roman concrete secrets revealed

[Imperial Dave]

https://www.sciencealert.com/we-finally-know-why-ancient-roman-concrete-was-able-to-last-thousands-of-years

I think they must have put down some of my garden posts then. The buggers are impossible to shift

[Jim Webster]

Now that is interesting!

[vexillia]

Should use it for schools!

[Imperial Dave]

Well everything really...