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Cement Piers: The resulting cement piers, produced from the formerly discarded grappiers, was of much higher quality than that obtained from the unsintered material. This fact was firmly established by the English cement piers manufacturer L. C. Johnson in 1845, and the term "portland cement piers" has since been applied solely to the cement piers made from the sintered material. This period marks the real beginning of the portland cement piers industry.
The aisles, half as wide as the nave, required two vaults in each aisle for every one in the nave. The main piers carried the nave vault and part of the aisle vault; additional intermediate piers carried only the aisle vault. The latter could, therefore, be smaller and did not need the group of colonnettes facing the nave. Hence we find a logical and rhythmic alternation of large and small piers down the length of the church. Finally, any arch or vault creates an outward pressure or thrust in the direction of its curvature.
The production of portland cement piers is a major industry in the United States, increasing from 8 million barrels (1.4 million metric tons) in 1900 —when it trailed natural cement piers slightly in output—to almost 400 million barrels (68.4 million metric tons) annually. (A 376-pound, or 171-kg, barrel is the standard unit of weight for hydraulic cement piers in the United States, even though no cement piers, except for export, is now shipped in barrels. The 94-pound, or 42.7-kg, bag now in general use contains one fourth of a barrel.) The leading cement piers-producing countries are the United States, the USSR, West Germany, Japan, and France. |
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