Concrete Construction for Rural CommunitiesMcGraw-Hill, 1916 - 223 páginas |
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Palavras e frases frequentes
28 days abutments amount applied batch beam bottom bracing brick bridges broken stone building blocks cement and sand cent Chapter clay coarse aggregate coat color column compressive compressive strength consistency construction cost cracks crete cubic foot cubic yards culverts cylinder depth desired diameter face factor of safety feet filled finish floor foot forms Gage given hydrated lime inches inches thick joints less lime machine materials mesh metal lath method mixed mixer mixture moist air mold mortar natural cement particles placed plaster Portland cement posts pounds pressure produce proportions quantities reinforced concrete removed safe load sample screen shoveled shown in Fig side sidewalks sieve silage silo slab Spacing span specific gravity square steel stone or gravel strength stresses stucco studs sufficient surface TABLE tanks temperature tensile strength test pieces tile trowel usually volume walls waterproofing weight width wire
Passagens conhecidas
Página 98 - If the percentage of elongation of any tension test specimen is less than that specified in Section 6 (a) and any part of the fracture is outside the middle third of the gage length, as indicated by scribe scratches marked on the specimen before testing, a retest shall be allowed.
Página 23 - ... sliced off at the top of the ring by a single oblique stroke of a trowel held at a slight angle with the top of the ring. During these operations care must be taken not to compress the paste.
Página 22 - App«r«tus. bearing a movable rod B, weighing 300 g., one end C being 1 cm. in diameter for a distance of 6 cm., the other having a removable needle D, 1 mm. in diameter, 6 cm. long. The rod is reversible, and can be held in any desired position by a screw E, and has midway between the ends a mark F which moves under a scale (graduated to millimeters) attached to the frame A. The paste is held in a conical, hard-rubber ring G, 7 cm.
Página 17 - F. as practicable, and observed at intervals for at least 28 days. (c)^ A third pat is exposed in any convenient way in an atmosphere of steam, above boiling water, in a loosely closed vessel for five hours. 23. These pats, to satisfactorily pass the requirements, shall remain firm and hard, and show no signs of distortion, checking, cracking, or disintegrating.
Página 18 - Faulty character of cement results more frequently from imperfect preparation of the raw material or defective burning than from incorrect proportions of the constituents. Cement made from very finely-ground material, and thoroughly burned, may contain much more lime than the amount usually present and still be perfectly sound. On the other hand, cements low in lime may, on account of careless preparation of the raw material, be of dangerous character. Further, the ash of the fuel used in burning...
Página 21 - The operation is continued until not more than onetenth of 1 per cent, passes through after one minute of continuous sieving. The residue is weighed, then placed on the No. 100 sieve and the operation repeated. The work may be expedited by placing in the sieve a small quantity of large shot. The results should be reported to the nearest tenth of 1 per cent.
Página 30 - 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.
Página 24 - Care shall 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 may increase the penetration. The time of setting is affected not only by the percentage and temperature of the water used and the amount of kneading the paste receives, but by the temperature and humidity of the air, and its determination is therefore only approximate.
Página 15 - The cement shall be stored in such a manner as to permit easy access for proper inspection and identification of each shipment, and in a suitable weather-tight building which will protect the cement from dampness.
Página 16 - This term is applied to the finely pulverized product resulting from the calcination to incipient fusion of an intimate mixture of properly proportioned argillaceous and calcareous materials, and to which no addition greater than 3% has been made subsequent to calcination.