The Cement Industry of the Lehigh Valley.
By David Prentice
It is hard to imagine a world without concrete. Concrete makes possible more construction on a greater scale than would have been possible with stone, brick or lime. Portland cement is the powder that, combined with sand, aggregate and water, creates concrete. It was invented in England in the first half of the nineteenth century. But in the Lehigh Valley, between 1871 and 1899, three events occurred that changed the American, and then the international Portland cement industry. First, at Coplay, a few miles northwest of Allentown, in 1871, David O. Saylor successfully manufactured Portland cement for the first time in the United States. The second event occurred in 1889 at Coplay when Jose De Navarro successfully commercialized the rotary kiln. This was followed around 1900 when the rotary kiln was adapted to use pulverized coal rather than the more expensive fuel oil. As the price of cement fell and demand rose, in part due to the successful development of reinforced concrete as a building material, a cement boom began which then spread across the United States. Cement consumption increased almost ten fold from 1890 to 1913. The title of one trade journal was "The Cement Age". Until 1907 more than half of the Portland cement produced in the United States came from the Lehigh Valley. Even after the boom had subsided, the Lehigh Valley remained the largest producing district in the United States until 1970 and remains in the top five producing districts in 2004. The rotary kiln became the standard technology for cement manufacturing internationally and remains so in 2008.
Before the 1890s cement was mainly used as a mortar in brick or stone construction. Most mortar was made from lime or natural cement. Natural cement is manufactured by burning a naturally occurring mixture of limestone and clay in kilns. The output of the kiln is ground and the resulting cement is both stronger than lime and can set under water making it very useful for constructing canals, docks and any other construction that comes into contact with water. The secret of how to make natural cement was discovered in the late eighteenth century in England, with production beginning in 1796. Natural cement production began in the United States in 1818 when suitable materials were discovered near Syracuse, N.Y., while building the Erie Canal. Indeed, most centers of Natural cement production were initially discovered while building canals. Canals provided initial demand and then a low cost means of transportation for the bulky product when complete. The Lehigh Valley was no exception as suitable materials were discovered at the Lehigh Gap while building the Lehigh Canal in 1826. In 1830 cement production for the canal shifted from the Lehigh Gap to Siegfried, Northampton County, just a few miles northwest of Allentown, when more suitable raw materials were found there. The industry continued on a small scale after canal construction was completed for the center of Natural cement production was in the Hudson Valley at Rosendale, New York. In 1890 United States Geological Survey statistics report 76.2% of cement consumed in the United States was natural cement and 37.8% of natural cement was produced in Rosendale.