CHAPTER X 



PORTLAND CEMENT 



History of the Industry. The cement used by the ancient 

 Egyptian builders was a type similar to our present lime mortars. 

 There is no reason to beheve that they were famihar with any form 

 of hydraulic cement. The first use of this type of cement is 

 attributed to the Roman builders who used it in the great en- 

 gineering works of the early Empire. This cement was made 

 by burning a volcanic ash found abundantly in the vicinity of 

 Naples and called Pozzuolana. The product was called Puzzolan 

 cement. This type of cement differed very much from our 

 modern Portland cement both in composition and method of 

 production. A very similar cement is produced at the present 

 time from blast-furnace slag. Following the fall of the Empire 

 even this type of cement was forgotten and the great buildings 

 of the Middle Ages were laid up with plain lime mortars. 



In 1756 John Smeaton, an English engineer, began a series of 

 experiments with hydraulic cements for use in the construction 

 of the Eddystone lighthouse. When the results of these experi- 

 ments were made public in 1791 a number of men began experi- 

 ments and in 1796 a patent was given in England to a man by 

 the name of Parker. The product was also patented in France 

 about the same time and both products were very similar to our 

 present Rosendale cement. 



According to Eckel (op. cit., infra), the first compound ap- 

 proximating the composition of our present Portland cement was 

 manufactured in England under a patent granted to Joseph 

 Aspdin of Leeds, England, in 1824. No formula was given with 

 the application for the patent, so the definite composition of this 

 cement is unknown, but to it was given the name of Portland 

 cement on account of its close resemblance to the well-known 

 Oolitic limestone of Portland, a well-known building stone. 

 Aspdin 's cement was made from a mixture of chalk and clay and 

 was burned at a higher temperature than is necessary in the 

 manufacture of hydraulic cements. The method was to pulveri-ze 

 and then calcine a quantity of limestone in a furnace, then mix 

 it thoroly with an equal amount of clay in water, making a thick 

 paste. This mixture was then dried and calcined, and after 

 the carbon dioxide was driven off the mass was again powdered. 

 The resulting compound had the ability to harden under water. 



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