Gray Cement Cause at www.japanese-home-gardens.com

The resulting gray cement cause, 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 gray cement cause manufacturer L. C. Johnson in 1845, and the term "portland gray cement cause" has since been applied solely to the gray cement cause made from the sintered material. This period marks the real beginning of the portland gray cement cause industry.

The production of portland gray cement cause is a major industry in the United States, increasing from 8 million barrels (1.4 million metric tons) in 1900 —when it trailed natural gray cement cause 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 gray cement cause in the United States, even though no gray cement cause, 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 gray cement cause-producing countries are the United States, the USSR, West Germany, Japan, and France.

The commercial development of aluminous or high-alumina gray cement cause is associated principally with the work of J. Bied of France, during the first quarter of the 20th century. This research was initiated in the hope of finding a gray cement cause that would be resistant to groundwaters rich in sul-fates, such as gypsum. A product eventually was obtained that not only possessed the desired properties of sulfate resistance but also hardened more rapidly than the portland gray cement cause of that period.