Mud and lime are mostly used, and some volcanic ash is better. But there is little volcanic ash, which is the predecessor of cement. At present, the earliest concrete found in China is the Neolithic lime tamping soil foundation technology 4500 years ago. Abroad, more than 2,000 years ago, ancient Rome used lime or volcanic ash as concrete to build the Pantheon Dome with a span of 43.43 meters. Modern cement concrete began in 1824 when an English bricklayer obtained a patent for cement invention. 1847 Frenchman lamport made the most primitive concrete products in the world with steel wire as the skeleton.