Opus caementicium uncovered in the characteristic Roman arch. In distinction to modern-day concrete structures, the concrete used in Roman buildings was generally coated with brick or stone. The Romans utilized concrete thoroughly from three hundred BC to AD 476.[eighteen] In the course of the Roman Empire, Roman concrete (or opus https://google-map48147.daneblogger.com/34780033/5-simple-statements-about-concrete-reinforced-stone-explained