Patent GB-433059-A (GB)
Title: Process and apparatus for the manufacture of reinforced concrete hollow bodies
IPC: B28B23/12
Filed: 1934-02-09
Abstract: 433,059. Moulding reinforced - concrete bodies. FREYSSINET, E., 28, Rue St-James, Neuilly-sur-Seine, France. Feb. 9, 1934, No. 4374. Convention date, Feb. 10, 1933. [Class 87 (ii)] [See also Group X] In the manufacture of hollow bodies from reinforced concrete, the moist concrete, together with non-rectilinear reinforcements, is placed between a deformable mould and a deformable mandrel, the concrete being first subjected to vibration or moderate compression, or the two combined, to eliminate excess water and then being subjected to a strong compression by expansion of the mandrel to tension the reinforcements and expand the mould, the article being removed from. the mould when the concrete is sufficiently hard to resist the tensioned reinforcements. The apparatus comprises a central mandrel having a rigid core 2 surrounded by a rubber envelope 1 and an outer mould 3. The core 2 may comprise concrete rings 5 surrounded by metal sheets 6. The envelope 1 is reinforced by longitudinal rods and is connected to the sheets 6 at its edges by rubber rings 7. The mould 3 comprises a series of wooden staves 11 impregnated with synthetic resin and supported by section irons 10 which are held in position by screw jacks 11<a> in an outer frame 14. Longitudinal reinforcements 22 are first fixed in the mould by pins 23 and subjected to tension by twisting their ends together in pairs as shown in Fig. 7 and tensioning them by tools 29 before the pins 23 are inserted. Circular hoops 21 are then wound around the reinforcements 22 and. an annular hopper is attached to the top of the mould. The mould is filled with moist concrete and vibrated by applying shocks to the irons 10 and also by producing a vibratory injection of fluid into the envelope 1 through the tubes 8 so that the excess water is evacuated through the staves 11 or rises into the hopper. The hopper is provided with knives for striking off excess concrete from the mould and, after its removal, lids 18 are clamped on. Fluid under pressure is then admitted to the envelope 1 and the jacks 11<a> are unscrewed by racks 17 so that the mould may expand and the reinforcements 21 may be tensioned. To accelerate the setting of the concrete it may be heated by pipes 11<b>. When the concrete has set the jacks 11<a> are fully unscrewed and the moulded pipe is removed vertically. In a modification, Fig. 2<b>, the screws 11<a> are replaced by wedges 11<d> which co-operate with similar wedges 11<e> on the irons 10 to adjust the size of the mould under the action of hydraulic jacks 14<b>. The irons 10 are supported by angle members b which roll on rollers c on the frame. In another modification, the irons 10 may be surrounded by a second elastic envelope inside a rigid outer frame and containing fluid under pressure. When the pressure in the core is increased above the pressure in the outer envelope the mould expands. When making hollow bodies for floors, Fig. 9, the mould has movable side walls 35 and a number of mandrels 38. The longitudinal reinforcements are tensioned by gripping members 41 and the moulds are stacked in a frame 42. Jacks 43 bear against the mould walls and the moulds are first filled and vibrated and the concrete is then compressed by expanding the mandrels 38. On releasing the jacks 43 the mould expands and tensions the transverse reinforcements. Specification 431,484 is referred to.