@shawngoldwater There are surely tricks about concrete the Romans knew that we don't; on the other hand, they'd be amazed by what the #CivilEngineering department at the #UDeSherbrooke can do, to say nothing of the #WorldOfConcrete annual exposition, https://www.worldofconcrete.com/en/attendee.html .

Our concrete doesn't last as long as that of the Romans because we put it in tension; we use steel reinforcing to resist the tension; and then we expose the #ReinforcedConcrete to salts and heavy live loads.