Cement is shipped in barrels or in cotton or paper bags.
The usual dimensions of a barrel are: length 2 ft. 4 in., middle diameter 1 ft. 41 in., end diameter 1 ft. 3.1 in.
The bags hold 50, 100, or 200 pounds.
Rosendale, N. Y. 300 lb. net Itosendale, Western 265 " Portland 375 " A barrel of Rosendale cement contains about 3.40 cubic feet and will make from 3.70 to 3.75 cubic feet of stiff paste, or 79 to S3 pounds will make about one cubic foot of paste. A barrel of Rosendale cement (300 lb.) and two barrels of sand (71 cubic,feet) mixed with about half a barrel of water will make about 8 cubic feet of mortar, sufficient for A barrel of Portland cement contains -,bout 3.25 to 3.35 cubic feet-100 pounds will make about one cubic foot of stiff paste.
A barrel of cement measured loosely increases considerably in bulk. The following results were obtained by measuring in quan tities of two cubic feet: 1 bbl. Norton's Rosendale gave 4.37 cu. ft.
" Anchor Portland gave 3.65 " " Sphinx Portland gave 3.71 " " Buckeye Portland gave.. • 4.25 " • Preservation of Cements. Cements require to be stored in a dry place protected from the weather; the packages should not be placed directly on the ground, but on boards raised a few inches from it. If necessary to stack it out of doors a platform of planks should first be made and the pile covered with canvas. Port land cement exposed to the atmosphere will absorb moisture until it is practically ruined. The absorption of moisture by the natural cements will cause the development of carbonate of lime, which will interfere with the subsequent hydration.
ri 1 SC E L LA NEOUS CEMENTS.
Slag Cements are those formed by an admixture of slaked lime with ground blast-furnace slag. The slag used has approximately the composition of an hydraulic cement, being composed mainly of silica and alumina, and lacking a proper proportion of lime to render it active as a cement. In preparing the cement the slag upon coming
from the furnace is plunged into water and reduced to a spongy form from which it may be readily ground. This is dried and ground to a fine powder. The powdered slag and slaked lime are then mixed in proper proportions and ground together, so as to very distribute them through the mixture. It is of the first importance in a slag cement that the slag be very finely ground, and that the ingredients be very uniformly and intimately incorporated.
Both the composition and methods of manufacture of slag cements vary considerably in different places. They usually con tain a higher percentage of alumina than Portland cements, and the materials are in a different state of combination, as, being mixed after the burning, the silicates and aluminates of lime formed during the burning of Portland cement cannot exist in slag cement.
The tests for slag cement are that briquettes made of one part of cement and three parts of sand by weight shall stand a tensile strain of 140 pounds per square inch (one day in air and six in water), and must show continually increasing strength after seven days, one month, etc. At least 90 per cent must pass a sieve containing 40,000 meshes to the square inch, and must stand the boiling test.
Pozzuolanas are cements made by a mixture of volcanic ashes with lime, although the name is sometimes applied to mixed cements in general. The use of pozzuolana in Europe dates back to the time of the Romans.
Roman Cement is a natural cement manufactured from the septaria nodules of the London Clay formation; it is quick-setting, but deteriorates with age and exposure to the air.