...The Physical, Chemical and Economic Properties of Building Stones

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Johns Hopkins Press, 1898 - 123 Seiten
 

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Seite 64 - Merrill a explains the cause of these contrasts very satisfactorily : The impact of the hammer breaks up the granules on the immediate surface, so that the light falling upon it is reflected, instead of absorbed, and the resultant effect upon the eye is that of whiteness. The darker color of a polished surface is due merely to the fact that, through careful grinding, all these irregularities and reflecting surfaces are removed, the light penetrating the stone is absorbed, and the effect upon the...
Seite 67 - ... which Frederick is situated, and through which flows the Monocacy River from north to south, entering the Potomac River at the boundary line between Montgomery and Frederick counties. The valley near Frederick has an elevation of 250 feet above tide, which changes slowly to the eastward toward Parr's Ridge, and very rapidly to the westward toward Catoctin Mountain. Situated on the eastern side of the valley, just above the mouth of the Monocacy River, and breaking the regularity of this surface...
Seite 106 - ... in the construction of the White House and the old portions of the Capitol, Interior Department and Treasury buildings. This stone has proven so poor and disintegrates so badly that the buildings are kept in a condition anywise presentable only by repeated applications of paint and putty. The results obtained with hard and soft brick are also very striking; the one weighing at the rate of 138 pounds per cubic foot, losing 16.46 grains, while the harder brick, weighing at the rate of 143 pounds,...
Seite 105 - Each v.*as immersed for half an hour in the boiling solution of sulphate of soda, and then hung up to dry, this performance being repeated daily throughout the four weeks which the experiment lasted. Although as above noted this process is practically abandoned, the series of tests given was productive of certain results which are well worth a moment's consideration. Thus the red sandstone from Seneca Creek, Maryland,, with a specific gravity of 2.672, or a weight per cubic foot of 167 pounds, lost...
Seite 65 - The results thus far obtained are sufficient for us to formulate general rules, and the average results obtained are so vastly in excess of all ordinary requirements that they may safely be ignored. A stone so weak as to be likely to crush in the walls of a building, or even in a window stool, cap or pillar, bears so visible marks of its unfitness as to deceive no one with more than an extremely rudimentary knowledge on the subject.
Seite 63 - It is for this same reason that the hammered surface of one of these rocks is of a lighter color than the natural rock face or polished surface. The impact of the hammer breaks up the granules on the immediate surface so that the light falling upon it is reflected, instead of absorbed, and the resultant effect upon the eye is that of whiteness. The darker color of a polished surface is due merely to the fact that through careful grinding all these irregularities and reflecting surfaces are removed,...
Seite 118 - Engineers the test consists in subjecting prepared prisms supported at each end by blocks 6 inches apart, to pressure applied by means of a " plunger " having a face 5 inches wide, there being then a clearance space of half an inch between the sides of the plunger and the blocks on each side, below (see Fig. 18). The results of a few experiments of this nature are given below. It is worthy of note that " before the shearing strength was reached during the tests, tension fractures were developed on...
Seite 115 - Engineers to which we have already referred 1 it was found that samples which had been submitted to the hot and cold water tests to ascertain their coefficient of expansion and contraction had suffered to a remarkable degree. The average result showed that the stones from the water baths lost in strength on an average 34.9 per cent, the granites, after passing through both hot and cold water tests, possessing but 83.7 per cent their original strength; the marbles 46.2 per cent; the limestones 58.8...
Seite 100 - California building stones,' and the efficiency of the method seems fairly well established. (2) Tests to ascertain resistance to corrosion. The question to be settled here is one relating chiefly to calcareous rocks, to limestones and marbles, or to sandstones containing a calcareous cement. The most satisfactory method available, is apparently that of Prof. Dodge, given in the publication above referred to, which is as follows: A set of pieces of essentially the same size and shape as those used...
Seite 109 - Col.Totten, in view of the difficulty of making permanently tight joints even with the strongest cements, instituted a series of experiments to ascertain the actual expansion and contraction of granite, sandstone and marble when subjected to ordinary temperature. He found the rate per inch for each degree of temperature for granite to be .000004825 inch; for marble .000005668 inch, and for sandstone .000009532 inch. That is to say a block of stone one foot in length raised from a temperature of freezing...

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