Opus caementicium exposed in a characteristic Roman arch. In contrast to modern concrete constructions, the concrete used in Roman structures was generally protected with brick or stone. The Romans made use of concrete extensively from 300 BC to Advert 476.[18] Throughout the Roman Empire, Roman concrete (or opus caementicium) was https://prefabricated-house61481.digiblogbox.com/60326069/5-essential-elements-for-reinforced-concrete-meaning