GB1011036A - Improvements in or relating to the production of hollow concrete articles - Google Patents

Abstract

1,011,036. Moulding hollow concrete articles. DOW-MAC (PRODUCTS) Ltd. Dec. 19, 1963 [Sept. 24, 1963], No. 37450/63. Heading B5A. A method of manufacturing an elongated concrete article 1 with an internal hollow or hollows 2 comprises arranging a plurality of rigid diaphragms 3, which will form a permanent part of the finished article, upright in spaced, face to face relation, passing wires through transverse apertures 8 in the diaphragms to form a core and securing them at their ends in tensioned condition to anchorages, covering the wires between the diaphragms with flexible sheet material,- and casting concrete around the core using a mould. Preferably the diaphragms are pre-cast concrete slabs 6 and may have integrally formed projections 7, corresponding in contour and position to the core. The projections may also be covered by the flexible sheet and may have apertures or grooves 8 through which the core wires pass. The projections may be annular concrete frames. The diaphragms may be provided with additional apertures 9 through which additional, preferably pre-tensioned reinforcing wires are passed. The hollows 2 may be tapered, in which case the core wires are converged by passing them through a steel retaining ring. The core wires may be removed after casting, in which case sheathing material, preferably P.V.C. is introduced into the diaphragm apertures before the casting operation. The ends of the articles may be formed hollow and then filled with concrete. The flexible sheet material may be water resistant paper, sisal kraft paper, rubber, canvas or plastics material, e.g. P.V.C. Articles made include beams and piles.