common clay
3.Printing originated in China. In the period between the Sui Dynasty in the second half of the 6th century and the Tang Dynasty in the first half of the early 7th century, lithographic printing was invented and, in the 9th century, a large number of books began to be printed by the lithographic process. In the reign of Emperor Qingli of the Northern Song Dynasty (960 A.D.-1127 A.D.), a common fellow named Bi Sheng invented printing by movable type and started to use baked clay types for printing. The technology was introduced to other countries in about the mid-8th century.
5.By using clay, bentonite,cement, fly ash, colliery powder addition agent as raw materials in this paper,the performance of common material for grouting were studied to solve practical problems of common slurry and find the reasonable dispensation formula meeting requirements of different projects.
