Portland Cement
Roman builders used volcanic tuff found near Pozzuoli village near Mount
Vesuvius in Italy. This volcanic tuff or ash mostly siliceous in nature thus acquired the name
Pozzolana. Later on, the name Pozzolana was applied to any other material, natural or
artificial, having nearly the same composition as that of volcanic tuff or ash found at Pozzuoli.
Romans added blood, milk and lard to their mortar and concrete to
achieve better workability. Haemoglobin is a powerful air-entraining agent and plasticizer,
which perhaps is yet another reason for the durability of Roman structures.
Joseph Aspdin took the patent of portland cement on 21st October 1824. The fancy name of portland was given owing to the resemblance of this hardened cement to the natural stone occurring at Portland in England.
See an overview of the cement manufacturing process in this 7-minute animation.
Common materials used to manufacture cement include limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore. These ingredients, when heated at high temperatures form a rock-like substance that is ground into the fine powder that we commonly think of as cement.
Cement manufacturing process:
http://www.cement.org/cement-concrete-basics/how-cement-is-made
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