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

ALTHOUGH CRAZY paving has often been sneered at, there is a great deal to be said for it, provided that the broken stone of which it is constructed is natural and also that it is properly laid. It is those bits of broken cement or synthetic paving, or stretches of cement marked out in a random pattern, or poorly fitted paving with ugly, thick mortar joints that have given crazy paving a bad name. Properly laid random paving can look perfect in a rural setting, although it is inclined to seem out of place in cities or with avant-garde architecture. If you intend to use natural stone for your crazy paving, bear in mind that the pieces are likely to vary considerably in thickness. Prepare the ground carefully if the paving is to present a flat, even surface.

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.