On Wed, 24 Nov 2004, Russell McMahon wrote:

> A basic form of concrete was discovered by the Greeks in about 3rd 
> century before Christ. Oldest known building using concrete is Temple of 
> Concord dated 121 BC.
>
> http://www.swan.ac.uk/classics/staff/ter/grst/What's%20what%20Things/concrete.htm

Imho anybody operating a kiln to smelt bronze should have discovered 
cement as soon as he'd have the kiln made of the wrong (or right ?) kind 
of stone, at the earliest after the next rain. So I think that concrete 
was known since sometime in the bronze age or before.

Peter

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