CEMENT

CEMENT. In Newly discovered lands, adventurers seek gold, while colonists seek limestone to make cement. American colonists made their first dwellings of logs, with chimneys plastered and caulked outside with mud or clay. To replace these early homes, the first bricks were imported. Brick masonry requires mortar; mortar requires cement.

Cement was first made of lime burned from oyster shells. In 1662 limestone was found at Providence, Rhode Island, and manufacture of "stone" lime began. Not until 1791 did John Smeaton, an English engineer, establish the fact that argillaceous (silica and alumina) impurity gave lime improved cementing value. Burning such limestones made hydraulic lime—a cement that hardens under water.

Only after the beginning of the country's first major public works, the Erie Canal in 1817, did American engineers learn to make and use a true hydraulic cement (one that had to be pulverized after burning in order to slake, or react with water). The first masonry on the Erie Canal was contracted to be done with common quick lime; when it failed to slake a local experimenter pulverized some and discovered a "natural" cement, that is, one made from natural rock. Canvass White, subsequently chief engineer of the Erie Canal, pursued investigations, perfected manufacture and use, obtained a patent, and is credited with being the father of the American cement industry. During the canal and later railway building era, demand rapidly increased and suitable cement rocks were discovered in many localities.

Cement made at Rosendale, New York, was the most famous, but that made at Coplay, Pennsylvania, the most significant, because it became the first American Portland cement. Portland cement, made by burning and pulverizing briquets of an artificial mixture of limestone (chalk) and clay, was so named because the hardened cement resembled a well-known building stone from the Isle of Portland. Soon after the Civil War, Portland cements, because of their more dependable qualities, began to be imported. Manufacture was started at Coplay, Pennsylvania, about 1870, by David O. Saylor, by selecting from his natural cement rock that was approximately of the same composition as the Portland cement artificial mixture. The Lehigh Valley around Coplay contained many similar deposits, and until 1907 this locality annually produced at least half of all the cement made in the United States. By 1900 the practice of grinding together ordinary limestone and clay, burning or calcining the mixture in rotary kilns, and pulverizing the burned clinker had become so well known that the Portland cement industry spread rapidly to all parts of the country. There were 174 plants across the country by 1971. Production increased from 350,000 barrels in 1890 to 410 million barrels in 1971.

At first cement was used only for mortar in brick and stone masonry. Gradually mixtures of cement, sand, stone, or gravel (aggregates) with water (known as concrete), poured into temporary forms where it hardened into a kind of conglomerate rock, came to be substituted for brick and stone, particularly for massive work like bridge abutments, piers, dams, and foundations.

BIBLIOGRAPHY

Andrews, Gregg. City of Dust: A Cement Company in the Land of Tom Sawyer. Columbia: University of Missouri Press, 1996.

Hadley, Earl J. The Magic Powder: History of the Universal Atlas Cement Company and the Cement Industry. New York: Putnam, 1945.

Lesley, Robert W. History of the Portland Cement Industry in the United States. Chicago: International Trade, 1924.

Nathan C.Rockwood/t. d.

See alsoBuilding Materials ; Housing .