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October 18, 1912 |
Railway Age Gazette |
Vol. 53, No. 16. |
Concrete Tanks |
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| In its 1911 report the committee reviewed the progress that had been made up to that time in the construction of concrete tanks and examples of tanks built for railway and other purposes were given. It is becoming quite usual at railway water stations to place the tank farther away from the track and deliver water to the engines through pipe lines and stand-pipes thereby making the water tank a more permanent structure. This practice reduces the need of a structure that can be moved on account of track changes and makes the concrete tank possible. The two great arguments in favor of the concrete tank are the permanence and minimum cost of maintenance. When the life of the tank is taken into consideration the latter will more than offset the increased cost of construction. The concrete tank is more costly than the wood or steel tank, but the steady increase in the price of lumber and the more improved methods of concrete construction are steadily reducing the difference. The committee is of the opinion that when subjected to the severest winter weather the concrete tank will stand up better than tanks of other materials. The above statement is based on conversations with various engineers who have had experience in water supply, and at present cannot be substantiated by facts. However, some concrete tanks are located where they are subjected to severe freezing weather and others are being considered therefore, it will not be long before this point can be determined definitely. Many arguments are advanced against the concrete tank, the chief one being that poor workmanship will result in a defective tank and cannot readily be discovered or remedied. The statement is true, but is also true of all other forms of construction. The remedy is careful, conscientious and competent supervision in selecting materials and doing the work. There is no form of concrete construction in which the care and judgment used in the selection and application of the materials is of more importance than in tank construction. Only cement of approved brands from reliable manufactures should be used. It should be delivered on the job in original packages and each consignment should be carefully tested. The sand gravel and crushed stone must be carefully examined for impurities and all such containing impurities must be rejected. The sizes of the various materials should be carefully considered and the proportions to be used determined in order that the resulting concrete will be as dense and watertight as possible. There seems to be a wide difference of opinion regarding the kind of a mixture that will produce the most compact and impervious concrete. Most specifications call for a wet mixture, yet occasionally the dry mixture is specified. L. Heidenreich says in his Engineer’s Pocket-book of Reinforced Concrete, “The author prefers for tanks a rather dry mixture of one part cement to four parts coarse sand well tamped. If a wet mixture is used the mortar or concrete is to contract in setting, thereby causing initial compressive stresses in the steel reinforcement. When the tank is filled the concrete will crack in various places until the steel received it tension stress. This the common cause of leaky tanks, which must be plastered or painted afterwards.” The decision as to what is best must be left to the engineer and is controlled by the material available his past experience. A concrete tank costs more than other tanks, but the first cost ought not to be the governing factor. A careful comparison should be made of different designs and styles of construction of tanks having the same capacity and serving the same purpose and cost per annum in each case arrived at. This cost is the average cost per year for the life of the structure and is made up of the original cost of the structure; the interest on the original cost for a period equal to the life of the structure; the total maintenance charges form the time expenditures are made until the end of the life of the structure and the risk or liability of destruction by storm or fire, whether covered by insurance or not. The total of the above items, divided by the number of years of life of the structure, equals the cost per annum. The report included descriptions of concrete tanks built for the Baltimore and Ohio at Sir Johns Run, W. Va.; for the cities of Norway, Mich., and Waverly, Ohio, and for the Chicago City Railway at Chicago. Committee: F. E. Weiss (C. M. & St. P.); W. H. Finley (C. & N. W.); W. M. Clark (B. & O.); D. C. Musser (Pennsylvania Lines West). Discussion C. E. Smith (Mo. Pac.) stated that a wet concrete should be used to insure a waterproof structure. A. S. Markley (C. & E. I.) believed that washed gravel should be used where a good mixture is desired and the concrete should also be mixed wet. R. H. Reid (L. S. & M. S.) believed that the concrete mixture should not be depended on to secure a watertight tank, but that it should also be waterproofed on the inside. J. B. Sheldon (N. Y., N. H. & H.) stated that the Atlas Cement Company had made a careful investigation with the conclusion that concrete can be mixed too wet, as well as too dry. W. M. Clark (B. & O.) believed that enough water should be used so that when the concrete is thoroughly rammed, the water will be drawn to the surface. He has had considerable experience with the repairing of old wooden tanks by reinforcing the inside with concrete. Five or six tanks on one division have been repaired in this way. |
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| Postscript: By the 1950's the concrete jug was gone and was replaced with a wooden jug. If anyone can provide information on when and why this occurred I would be grateful. Email may be sent to "kwmcb at earthlink dot net" Click on thumbnail for 26K image: |
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