Portland cement: its composition, raw materials, manufacture, testing and analysis

The Chemical publishing company, 1906 - 385 Seiten

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Seite 351 - Constancy of Volume. Pats of neat cement about three inches in diameter, one-half inch thick at the center, and tapering to a thin edge, shall be kept in moist air for a period of twenty-four hours. (a) A pat is then kept in air at normal temperature. (b) Another is kept in water maintained as near 70° F.
Seite 279 - A convenient method for cleaning the apparatus is as follows : The flask is inverted over a large vessel, preferably a glass jar, and shaken vertically until the liquid starts to flow freely; it is then held still in a vertical position until empty; the remaining traces of cement can be removed in a similar manner by pouring into the flask a small quantity of clean liquid and repeating the operation. 18. — More accurate determinations may be made with the picnometer.
Seite 173 - The precipitate shall be dissolved in a small quantity of hot hydrochloric acid, the solution diluted to about 100 cc, 1 cc of a saturated solution of sodium-ammonium-hydrogen phosphate added, and ammonia drop by drop, with constant stirring, until the precipitate is again formed as described and the ammonia is in moderate excess. The precipitate shall then be allowed to stand about two hours, filtered and washed as before.
Seite 320 - After 24 hours in moist air the test pieces for longer periods of time should be immersed in water maintained as near 21" Cent. (70° Fahr.) as practicable; they may be stored in tanks or pans, which should be of non-corrodible material.
Seite 301 - Care should be taken to keep the needle clean, as the collection of cement on the sides of the needle retards the penetration, while cement on the point reduces the area and tends to increase the penetration.
Seite 170 - ... minutes, or longer if the blast is not powerful enough to effect complete conversion to a cement in this time. It is then transferred to an evaporating dish, preferably of platinum for the sake of celerity in evaporation...
Seite 279 - The whole quantity of the powder is introduced, and the level of the liquid rises to some division of the graduated neck. This reading plus 20 cu. cm. is the volume displaced by 64 gr. of the powder. 15. — The specific gravity is then obtained from the formula: Weight of cement Specific gravity = Displaced volume 16. — The flask, during the operation...
Seite 173 - NH4OH is added drop by drop with constant stirring until the crystalline ammonium-magnesium ortho,phosphate begins to form, and then in moderate excess, the stirring being continued for several minutes. It is then set aside for several hours in a cool atmosphere and filtered. The precipitate is redissolved in hot dilute...
Seite 299 - Cement. desired position by a screw F, carries an indicator, which moves over a scale (graduated to centimeters) attached to the frame K. The paste is held by a conical, hard-rubber ring I, 7 cm.
Seite 300 - The setting is said to have commenced when the needle ceases to pass a point 5 mm. (0.20 in.) above the upper surface of the glass plate, and is said to have terminated the moment the needle does not sink visibly into the mass.

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