Patent GB-144426-A (GB)
Abstract: 144,426. Neilson, R. April 10, 1919. Tanks and cisterns. - Reinforcedconcrete cylinders and other vessels or hollow structures are rendered impervious to fluids by providing an inner layer of bitumen or bituminous material, which extends over the whole of the inner surface of the concrete and is itself protected from the corrosive action of the fluid by a coating of motar, cement, &c. The cylinders &c. are built up in such a manner as to minimize the formation of blow-holes in the bituminous layer and so as to enable the presence of such holes, if formed, to be ascertained and rectified before the completion of the manufacture of the cylinder &c. The composite cylinder &c. may be built up from the outside or from the inside. In the former case, the sections b, Fig. 1, are first built up and are formed of concrete reinforced by steel rings e or helical steel windings and also a series of longitudinal tubes f, which are so arranged that the tubes of the various sections register and are adapted to receive binding-rods g, which receive screw-nuts for securing the sections together; or, if the tubes are of greater diameter than the rods g, groutings of cement may be used to connect the rods to the tubes. A bituminous layer c is moulded on to the inside of the reinforced-concrete section b by positioning the sections b vertically over a base, sealing the outer-joint between each section and the base with hot bitumen, and, when this is set, pouring hot bitumen into the section, and displacing this vertically by a vertical plunger with a convex face. Sufficient bitumen is employed to line the whole of the section and also overlap the upper edge, and the base to which the section is secured is formed with an annular recess so as to mould an overlapping edge on the bottom of the section. The sections are tested by eye, or in a hydraulic machine, and then a mortar lining d is applied. In connecting up the sections to form a complete cylinder &c., the sections are placed vertically over one another with the tubes f in register, and steel rings i are placed between the abut. ting edges, and the overlapping edges c<1> of bitumen are heated and pressed together so as to ensure continuity of the bitumen. A grouting j of cement is finally placed between the adjoining sections. Very heavy sections are connected in a horizontal position by the aid of trolleys &c. and any means for applying longitudinal pressure. As shown in Fig. 3. mortar cylinders d are first moulded preferably with annular recesses d<1> for receiving an overlap of bitumen. The bitumen is moulded around the' cylinders d by stopping the ends of the cylinders and causing the cylinders d to displace the bitumen c, which is placed in an outer concentric mould. A continuous outer reinforced-concrete layer b is then moulded around a number of inner sections. which are connected together by melting the bitumen at the junction of the sections and pressing them together. In a further modification, as shown in Fig. 3, cylinders are built up in situ; as shown in Fig. 5, two units built up as described above are connected together by means of rods p engaging in registering tubes m, n, which are strengthened by reinforcing steel hoops or spirals o. Steel rings q are arranged between the tubes m, n and the flanges of bitumen, which are united by heat. The joint is secured by applying longitudinal pressure by jacks &c., and cement groutings are finally used to secure the rods p in position and to close the annular space between the pipe sections.