Opus caementicium exposed inside of a characteristic Roman arch. In distinction to modern day concrete buildings, the concrete Utilized in Roman properties was generally protected with brick or stone. The Romans utilized concrete extensively from three hundred BC to AD 476.[18] Through the Roman Empire, Roman concrete (or opus caementicium) https://judo63950.thezenweb.com/an-unbiased-view-of-concrete-reinforced-retaining-wall-73919977