Cement Curb at www.japanese-home-gardens.com

THE USE of gravel as a paving material can be very effective in many styles of garden. Furthermore, it is easy to lay and easy to maintain. However, you must take steps to restrict the tiny stones to the pathway by providing some form of positive edging, such as bricks laid on edge or cement curb stones bedded in sand or cement, or even stout preservative-treated boards secured by stakes driven into the ground.

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

The production of portland cement 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 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 in the United States, even though no cement, 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-producing countries are the United States, the USSR, West Germany, Japan, and France.