Directory of American Cement Industries and Hand-book for Cement Users

Capa
Municipal engineering Company, 1901
 

Outras edições - Ver todos

Termos e frases comuns

Passagens mais conhecidas

Página 106 - ... air and seven days in water, and shall be mixed in the proportion of one part of cement to three parts of crushed granite.
Página 89 - The tensile strength, limit of elasticity and ductility shall be determined from a standard test piece cut from the finished material. The standard shape of the test piece for sheared plates shall be as shown.
Página 22 - One of these cakes, when hard enough, should be put in water and examined from day to day to see if it becomes contorted, or if cracks show themselves at the edges, such contortions or cracks indicating that the cement is unfit for use at that time. In some cases the tendency to crack, if caused by the presence of too much unslaked lime, will disappear with age.
Página 25 - In selecting cement for experimental purposes, take the samples from the interior of the original packages, at sufficient depth to insure a fair exponent of the quality, and store the same in tightly closed receptacles impervious to light or dampness until required for manipulation, when each sample of cement should be so thoroughly mixed, by sifting or otherwise, that it shall be uniform in character throughout its mass.
Página 21 - The testing of cement is not so simple a process as it is sometimes thought to be. No small degree of experience is necessary before one can manipulate the materials so as to obtain even approximately accurate results. "The first tests of inexperienced, though intelligent and careful persons, are usually very contradictory and inaccurate. and no amount of experience can eliminate the variations introduced by the personal equation of the most conscientious observers.
Página 85 - The number and arrangement of the piles for each foundation shall be shown on plans, and they shall be sawed off at the elevations shown.
Página 11 - Portland cement is meant the product obtained from the heating or calcining up to incipient fusion of intimate mixtures, either natural or artificial, of argillaceous with calcareous substances, the calcined product to contain at least 1.7 times as much of lime, by weight, as of the materials which give the lime its hydraulic properties, and to be finely pulverized after said calcination, and thereafter additions or substitutions for the purpose only of regulating certain properties of technical...
Página 51 - ... cement. Each barrel must be properly lined with paper or other material so as to effectually protect the cement from dampness. Any cement damaged by water to such an extent that the damage can be ascertained from the outside will be rejected in toto and the barrels unopened. Barrels containing a large proportion of lumps will also be rejected. Broken barrels of cement. if otherwise satisfactory, will be counted as half-barrels.
Página 25 - SAMPLING There is no uniformity of practice among engineers as to the sampling of the cement to be tested, some testing every tenth barrel, others every fifth, and others still every barrel delivered. Usually, where cement has a good reputation, and is used in large masses, such as concrete in heavy foundations or in the backing or hearting of thick walls, the testing of every fifth barrel seems to be sufficient; but in very important work, where the strength of each barrel may in a great measure...
Página 23 - The quantities used in the mixture should be determined by weight. The tests should be applied to the cements as offered for sale. If satisfactory results are obtained with a full dose of sand, the trials need go ' no further. If not, the coarser particles should first be excluded by using a No. 100 sieve, in order to determine approximately the grade the cement would take if ground fine; for fineness is always attainable, while inherent merit may not be.

Informações bibliográficas