Bulletin - Geological Survey of Alabama, Issues 7-10

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Geological Survey of Alabama, 1903 - Geology

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Page 12 - By a 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...
Page 42 - ... limestone (cement rock) mixed with a comparatively small quantity of purer limestone, as in the Lehigh plants, requires less thorough mixing and less fine grinding than when a mixture of limestone and clay (or marl and clay) is used, for even the coarser particles of the argillaceous limestone will vary so little in chemical composition from the proper mixture as to affect the quality of the resulting cement but little should either mixing or grinding be incompletely accomplished. A very good...
Page 10 - ... of the clayey materials. The burning takes place at a high temperature, approaching 3,000 F., and must therefore be carried on in kilns of special design and lining. During the burning, combination of the lime with silica, alumina, and iron oxide takes place. The product of the burning is a semifused mass called clinker, and consists of silicates, aluminates, and ferrites of lime in certain definite proportions.
Page 56 - This may seem, at first sight, improbable, for Portland cement clinker is much harder to grind than any possible combination of raw materials; but it must be remembered that for every barrel of cement produced about 600 pounds of raw materials must be pulverized, while only a scant 400 pounds of clinker will be treated, and that the large crushers required for some raw materials can be dispensed with in crushing clinker. With this exception, the raw material side and the clinker side of a dry-process...
Page 19 - MgCO3 and being composed of 47.6 per cent magnesia (MgO) and 52.4 per cent carbon dioxide (CO2). liocks of the limestone series may therefore vary in composition from pure calcite limestone at one end of the series to pure magnesite at the other. The term limestone has, however, been restricted in general use to those rocks which have a composition between that of calcite and dolomite.
Page 15 - Portland cement mixture, when ready for burning, will consist of about 75 per cent. of lime carbonate (CaCO,) and 20 per cent. of silica (Si0j), alumina (A1j0j) and iron oxide (Fej08) together, the remaining 5 per cent. including any magnesium carbonate, sulphur and alkalies that may be present. The essential elements which enter into this mixture — lime, silica, alumina, and iron — are all abundantly and widely distributed in nature, occurring in different forms in many kinds of rocks. It can...
Page 15 - ... a mixture of correct composition. The almost infinite number of raw materials which are theoretically available are, however, reduced to a very few in practice under existing commercial conditions. The necessity for making the mixture as cheaply as possible rules out of consideration a large number of materials which would be considered available if chemical composition was the only thing to be taken into account. Some materials otherwise suitable are too scarce; some are too difficult to pulverize....
Page 17 - Deposition from solution by purely chemical means has undoubtedly given rise to numerous limestone deposits. When this deposition took place in caverns or in the open air it gave rise to onyx deposits and to the "travertine marls" of certain localities in Ohio and elsewhere. When it took place in isolated portions of the sea through the evaporation of the sea water it gave rise to the limestone beds which so frequently accompany deposits of salt and gypsum.
Page 13 - Portland cement is an artificial product, obtained by finely pulverizing the clinker produced by burning to semifusion an intimate mixture of finely ground calcareous and argillaceous material, this mixture consisting, approximately, of one part of silica and alumina to three parts of carbonate of lime (or an equivalent amount of lime).
Page 119 - ... creek bottoms of the country near the limestone outcrops, and of the clays of the Grand Gulf formation, which very generally in this section overlies the limestone. Some analyses of the last named clays have been made from material occurring near St.

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