ABSTRACT
Cement can be manufactured either from natural cement stones or artificially by using calcareous and argillaceous materials. The examples of natural cements are Roman cement, Puzzolana cement and Medina cement and those of artificial cement are Portland cement and special cements. Cement can be manufactured either by dry process or wet process. The approximate limits of chemical composition in cement are shown. The factors responsible for the physical properties of concrete are the extent of hydration of cement and the resultant microstructure of the hydrated cement. Soundness of cement may be tested by Le-Chatelier method or by autoclave method. Heat is evolved during hydration of cement, the amount being dependent on the relative quantities of the clinker compounds. An increase in the fineness of the cement increases the cohesiveness of the concrete mix and thus reduces the amount of water which separates to the top of a lift, particularly while compacting with vibrators.
