Hydraulic Cement: Its Properties, Testing, and UseWiley & sons, 1903 - 265 páginas |
Otras ediciones - Ver todas
Términos y frases comunes
aluminate of lime ammonia apparatus block boiling test briquettes burning cakes calcium calcium sulphate Candlot carbonate carbonic acid cause cement-mortar centimeters Chatelier chloride Civil Engineers commonly consistency cracks cylinder day in air determined diameter disintegration effect employed Fahr flask free lime fresh water gauging give grains grammes grappiers heat hydrated hydraulic index hydraulic lime hydrochloric acid immersed laboratories Le Chatelier less liquid loss of strength machine magnesia material measure Methods of Testing millimeters mixed mortar mould natural cements neat cement needle obtained ordinary porosity Portland cement powder Prof proportion quantity of water quick-setting quicklime rate of setting recommended Roman cement salts sand-mortar sea-water shown in Fig sieve silica slag slaking slow-setting Society of Civil specific gravity specifications specimen standard tests sufficient sulphate of lime sulphuric acid surface swelling temperature tensile strength Tetmajer tion tube uniform unsoundness usually varies volume weight
Pasajes populares
Página 162 - 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 49 - Activity denotes the speed with which a cement begins to set. Cements differ widely in their rate and manner of setting. Some occupy but a few minutes in the operation, and others require several. Some begin setting immediately and take considerable time to complete the set, while others stand for a considerable time with no apparent action and then set very quickly. The point at which the set is supposed to begin is when the stiffening of...
Página 245 - Masons very frequently mix mortar in considerable quantities, and if the mass becomes stiffened before being used, by the setting of the cement, add water and work it again to a soft or plastic condition. After this second tempering the cement is much less active than at first, and will remain for a longer time in a workable condition. This practice is condemned by engineers, and is not usually allowed in good engineering construction.
Página 115 - The first test 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 equations of the most conscientious observers. Many things, apparently of minor importance, exert such a marked influence upon the results, that it is only by the greatest care in every particular, aided by experience and intelligence that trustworthy tests can be made.
Página 229 - In mixing cement mortar the cement and sand are first thoroughly mixed dry, the water then added, and the whole worked to a uniformly plastic condition. The quality of the mortar depends largely upon the thoroughness of the mixing, the great object of which is to so thoroughly incorporate the ingredients that no two grains of sand shall lie together without an intervening layer or film of cement. To accomplish this the cement must be uniformly distributed...
Página 115 - 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...
Página 162 - It is as follows: make two cakes of neat cement, 2 or 3 inches in diameter, about -J- inch thick, with thin edges. Note the time in minutes that these cakes, when mixed with water to the consistency of a stiff plastic mortar, take to set hard enough to stand the wire test recommended by Gen.
Página 155 - The question of a standard sand seems one of great importance, for it has been found that sands looking alike and sifted through the same sieves give results varying within rather wide limits. The material that seems likely to give the best results is the crushed quartz used in the manufacture of sandpaper. It is a commercial product, made in large quantities and of standard grades, and can be furnished of a fairly uniform quality. It is clean and sharp, and, although the present price is somewhat...
Página 173 - For making the heat test, a stiff paste of neat cement and water is made, and from this cakes 8 cm. to 10 cm. in diameter and 1 cm. thick are formed on a smooth impermeable plate covered with blotting paper. Two of these cakes which are to be protected against drying in order to prevent drying cracks, are placed after the lapse of twenty-four hours, or at least only after they have set, with their smooth surface on a metal plate and exposed for at least one hour to a temperature of from 110° C.
Página 124 - ... level; the molds in each instance, while being charged and manipulated, to be laid directly on glass, slate or some other non-absorbent material. The molding must be completed before incipient setting begins. As soon as the briquettes are hard enough to bear it, they should be taken from the molds and be kept covered with a damp cloth until they are immersed.