LIBRARY OP THK UNIVERSITY OF CALIFORNIA. Class MOLDING CONCRETE BATH TUBS, AQUARIUMS AND NATATORIUMS Houghton's Concrete Worker's Reference Books POPULAR 50c. HAND BOOKS Concrete Wall Forms . . . . 50c. Concrete Floors and Sidewalks . . SOc. Practical Silo Construction . . 50c. Molding Concrete Chimneys, Slate and Roof Tiles SOc. Molding and Curing Ornamental Concrete SOc. Concrete Monuments, Mausoleums and Burial Vaults SOc. Molding Concrete Bath Tubs, Aquariums and Natatoriums .... SOc. Artistic Concrete Bridges . . .SOc. Constructing Concrete Porches . .SOc. Molding Concrete Flower Pots, Boxes, Jardinieres, Etc. . . . .SOc. Molding Concrete Fountains and Lawn Ornaments SOc. Concrete for the Farm and Shop . .SOc. Houghton's Other Practical Concrete Books Concrete from Sand Molds . . . 12.00 Ornamental Concrete Without Molds . 2.00 A * pedal circular of an* of the book* tail! be tent on rtquett. Any of these bock* tent prepaid on receipt of the price. THE NORMAN W. HENLEY PUBLISHING Co. 132 NASSAU STREET. NEW YORK MOLDING CONCRETE BATH TUBS, AQUARIUMS AND NATATORIUMS A PRACTICAL TREATISE EXPLAINING THE MOLDING IN CONCRETE OF VARIOUS STYLES OF BATH TUBS, LAUNDRY TRAYS, ETC., WITH EASILY CONSTRUCTED MOLDS FOR THE PURPOSE. THE MOLDING OF AQUARIUMS AND NATATORIUMS, AS WELL AS THE WATER-PROOFING METHODS USED FOR SAME, ARE FULLY TREATED. By A. A. HOUGHTON Author of " Concrete from Sand Molds," " Ornamental Concrete Without Molds," Etc., Etc Fully Illustrated by Original Drawings. NEW YORK THE NORMAN W. HENLEY PUBLISHING CO. 132 NASSAU STREET 1911 ... ..-- .... :...-.... -,, FIG. 16. Molding and water-proofing a concrete natatorium. AQUARIUMS AND NATATOBIUMS. 51 When the concrete has hardened enough to per- mit, the core form is removed, and the inside of the tank given a thick coat of asphalt, or even hot tar, tarred felt, or some perfect water-proof- ing material that will also act as a binder or ad- hesive between the two layers of concrete. The balance or second layer of the floor is then laid upon this asphalt coating and the core erected to . complete the wall to the desired thickness, the concrete being placed for same as soon as the asphalt coating is in place. This method places an absolute water-proof layer of material between the two sections of wall and floor, as shown by the dotted lines in Fig. 16. By having it nearly in the center of wall each layer of concrete is thick enough to stand the loading without cracking, even if the bond between layers is not perfect. The concrete pool or tank should be sloping with the greatest width at the top, so that in event of the water in same freezing at any time, the pressure would be far less than if the sides were vertical. The outside wall should have a footing of suffi- cient width to support the wall. This must rest upon solid ground or a foundation wall that is amply strong enough for the load, so that there is no possible danger of the wall settling and thus causing the concrete to crack and injure the use- fulness of the work. Where there is any danger 52 MOLDING CONCRETE BATH TUBS, from this cause, or in large pools of this kind, the work should have ample reinforcement by tying expanded metal or wire lath to steel rods or bars spaced at the proper distance apart to take all the strain. The concrete for the foundation may be mixed 1:3:6, using sharp sand, running from coarse to fine, and gravel not to exceed 2 inches in diameter, where the foundation walls are placed in a trench and below ground. This is covered with a 6-inch course of 1:2:4 mixture, well tamped, at the ground line. The body of the large pool may be built of well graded aggregates in the proportions of 1:2:4, using gravel or broken stone as the large aggregate. This is plastered upon the in- side with a coating of one part Portland cement to two parts of clean, sharp sand. The concrete must be mixed wet and well tamped or forced into place, so to reduce the amount of voids, allowing the forms to remain about two to three days, so to permit the concrete to harden before removing to apply the plaster coat. Openings for inlet and outlet are made by in- serting short sections of iron pipe in the concrete, or by using a tapering wood plug or form for opening. These should be well greased, so to prevent the concrete from adhering to same. AQUARIUMS AND NATATORIUMS. 53 WATER-PROOF CONCRETE Concrete that is made properly, so to secure the maximum density, is practically impervious to water with a low pressure. In this regard the proper proportioning of the materials, grading the aggregates so to leave the least percentage of voids, care and thoroughness in mixing, and the use of water in a quanity ample to thoroughly wet the mixture, are of the greatest importance in securing a dense and water-proof concrete. It is also of importance that the concrete should be a rich mix, where the work will permit, and if this is not possible, as upon large tanks, the inside surface should be plastered with a rich mixture. A rich mixture of concrete where subjected to a low water pressure is usually impermeable, and this increases with the age of the work. Where the joints occur in the work, special care should be given to the water-proofing, so that water-tightness may be assured. The water pressure against the surface of the concrete, must be considered in estimating the necessary water-proofing treatment. This is usu- ally from 15 pounds to 156 pounds per square foot of wall surface, and with a lifting pressure under a floor of 31 pounds to 312 pounds per square foot, for a hydrostatic head of 6 inches to 5 feet; for a head up to 10 feet, the pressure against the wall per square foot will be up to 312 pounds, and 54 MOLDING CONCRETE BATH TUBS, under a floor this will be doubled, or 624 pounds to the square foot. With a head of 15 feet, the wall pressure will be 468 pounds against each square foot of the wall surface; 20 feet gives a wall pressure of 625 pounds ; 25 feet a pressure of 781 pounds to the square foot of wall surface. With a hydrostatic head of 30 feet, the pressure against the wall will be 937 pounds ; above 30 feet in hydrostatic head the average pressure is easily estimated by multiplying the pressure at 20 feet, or 625 pounds, by the number of times 20 feet is contained in the estimated hydrostatic head. The lifting or pressure under a floor surface is usually estimated at double the water pressure against