MISCELLANEOUS USES OF REINFORCED CONCRETE In other chapters the main points in rein forced concrete construction work are treated. The use of reinforced concrete is becoming so general, and its possibilities are so numerous and of such a varied description, that in this rapidly advancing stage of the use of the material it is practically out of the question to cover every possible application. The fundamental and es sential principles do not vary to so great an extent.
The following pages are devoted to the de scription of a number of instances where rein forced concrete has either displaced some less stable form of building material, or has proved an innovation in a certain form of construction.
Concrete Coal Pocket. The use of reinforced concrete as a structural material is extending rapidly, and owners contemplating building are getting away from the old lines, out of the rut, as it were, and erecting structures which have all the advantages of the old method, none of their disadvantages, and at the same or a slight addi tional cost obtain a genuine fireproof structure on which it is a waste of money to carry insur ance, and on the contents of which the cost of insurance is only a small percentage of the cost 285 for the same material in a structure which can easily be destroyed by fire.
One of the many novel uses to which rein forced concrete has been put is the construction of large coal pockets for the storage of anthra cite coal.
One of these pockets has been constructed for the Lehigh & Wilkesbarre Coal Co., at Charles town, Mass., and is capable of holding 10,000 tons of coal. It is shown in process of construction in Plate 25. The owners decided to construct of concrete in order that they might have a build ing which would last for all time—one on which there would be no maintenance charges, and which positively could not burn down.
On the site of this new pocket there was originally a wooden pocket which was in use up to the time the construction of the new pocket was commenced. The old pocket had been erected about twelve years previously, and it was costing $1,000 each year to keep it from falling down—an equivalent of 5 per cent on an investment of $20,000.
The new pocket is 182 feet long, 92 feet wide, and 24 feet deep, and is set up on square columns arranged to allow the construction of paved driveways 13 feet wide, with a head-room of 10 feet 6 inches under the pocket, so that, in loading, a team may be driven through any of the driveways under the pocket containing the grade of coal desired. Upon reaching the proper chute,
the driver pulls a lever, releasing the coal, which passes over a screen into the wagon, giving a load of clean coal in the shortest possible time. In this way it is possible for a retail company to do the same amount of business with two-thirds of the teaming, compared with the old method of shoveling into wagons from storage piles.
The pocket was located on a filled area between two bulkheads, allowing a width of about 40 feet on one side. On the other side the wall of the pocket was located on the bulkhead line which necessitated filling out into the slip a width of 30 feet for a driveway. With such a great dead weight as the pocket and the coal, it was, of course, impossible to construct the foundations directly on the fill, as the probability was that there would be uneven settlement and possible serious damage to the pocket. It was therefore neces sary to build a pile foundation, as the absence of any firm bearing stratum precluded the use of deep footings owing to their prohibitive cost. It was eventually de termined to use concrete piles, these being more desirable in every way than wooden piles and actually costing less money.
In the event of using wood piles, the building laws would have required that they be cut off 10 feet below the surface of the ground, and a load of only ten tons could be carried on each pile. This would have necessi tated the use of three times as many wooden piles as concrete, and required an enormous amount of excava tion, bracing, and additional concrete to carry the foot ings down to grade. Necessity of tide work would have made the use of wooden piles more expensive and awk ward, because the excavated trenches would have filled with water at each rise of the tide, necessitating pump ing, submerging fresh concrete at each tide, and making progress slow and difficult. The construction of a coffer dam around the site was out of the question because of the expense involved. Concrete piles were selected because of their unquestioned durability and their greater supporting power and economy.