Opus caementicium exposed inside of a characteristic Roman arch. In distinction to modern concrete constructions, the concrete Employed in Roman structures was usually lined with brick or stone. The Romans used concrete extensively from 300 BC to Advert 476.[18] In the course of the Roman Empire, Roman concrete (or opus https://deanmslew.blogripley.com/36554985/an-unbiased-view-of-reinforced-concrete-meaning