Design and construction of hydroelectric plants: including a special treatment of the design of dams

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McGraw publishing company, 1907 - Hydroelectric power plants - 512 pages
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Page 69 - Method. — As a method to be followed for the analysis of cement, that proposed by the Committee on Uniformity in the analysis of Materials for the Portland Cement Industry, of the New York Section of the Society for Chemical Industry, and published in the Journal of the Society for January 15, 1902, is recommended.
Page 79 - The object is to develop those qualities which tend to destroy the strength and durability of a cement. As it is highly essential to determine such qualities at once, tests of this character are for the most part made in a very short time, and are known, therefore, as accelerated tests. Failure is revealed by cracking, checking, swelling, or disintegration, or all of these phenomena. A cement which remains perfectly sound is said to be of constant volume.
Page 80 - F.) and upward. The test pieces should be allowed to remain 24 hours in moist air before immersion in water or steam, or preservation in air.
Page 70 - Inasmuch as the differences in specific gravity are usually very small, great care must be exercised in making the determination. When properly made, this test affords a quick check for underburning or adulteration. Apparatus and Method — The determination of specific gravity is most conveniently made with LeChatelier's apparatus.
Page 78 - A moist closet or chamber is so easily devised that the use of the damp cloth should be abandoned if possible. . Covering the test pieces with a damp cloth is objectionable, as commonly used, because the cloth may dry out unequally, and, in consequence, the test pieces are not all maintained under the same condition. Where a moist closet is not available, a cloth may be used and kept uniformly wet by immersing the ends in water.
Page 80 - In the present state of our knowledge it cannot be said that cement should necessarily be condemned simply for failure to pass the accelerated tests; nor can a cement be considered entirely satisfactory, simply because it has passed these tests.
Page 78 - Test pieces should be broken as soon as they are removed from the water. Care should be observed in centering the briquettes in the testing machine, as cross-strains, produced by improper centering...
Page 77 - ... proper percentage of clean water is poured; the material on the outer edge is turned into the crater by the aid of a trowel. As soon as the water has been absorbed, which should not require more than one minute, the operation is completed by vigorously kneading with the hands for an additional 1J minutes, the process being similar to that used in kneading dough.
Page 214 - But it is only within the last few years that it has been possible to realise something of the beauty and significance of this
Page 75 - The determination of the time of setting is only approximate, being materially affected by the temperature of the mixing water, the temperature and humidity of the air during the test, the percentage of water used, and the amount of molding the paste receives.

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