On Tuesday, July 4, 2017 at 1:29:55 PM UTC-7, Stormin' Norman wrote:
I have always been amazed by Roman concrete, particularly the
hydraulic-setting concrete which they used to construct piers and
other harbor structures.

Scientists explain ancient Rome's long-lasting concrete

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

It was not union made.