GB1466663A - Producing products from dry particulate material and a liquid - Google Patents

Abstract

1466663 Wetting concrete G MATTHEWS RESEARCH & DEVELOPMENT CO Ltd 2 April 1974 [18 April 1973] 18737/73 Heading B5A Dry particulate material (e.g. cement with granite, or quick setting plaster of Paris with exfoliated mica) is placed in a mould, and a vacuum applied to a first portion of the surface of the material to cause compaction. Liquid (e.g. water) is applied to a second part of the surface for drawing in by the vacuum. Further compaction does not occur after the liquid has been applied to the surface. As described for moulding concrete articles, a wetted filter paper is placed in each of an endless procession of pivotally interconnected moulds 20 (Fig. 3), to the base of each of which a vacuum is supplied by a pair of pipes 28. A hopper 48 containing a dry white cement, granite and colour pigment moves along with, and above, a first mould, moves down into the mould, and distributes the coloured cement &c. on the filter paper. The hopper 48 then rises and moves back to an initial position due to a counterweight 49, to repeat the feeding with successive moulds. As the moulds pass beneath a hopper 33, coloured or uncoloured dry cement and granite are sprinkled to fill the moulds, and the cement is levelled by a roller 60, while compacted by the applied vacuum. Water is sprayed from a pipe 64 (or flooded on from a filter cloth endless belt) and sucked into the cements, and excess removed, by the vacuum. As each mould base contacts a fixed rail, the vacuum is released from the contacting mould and replaced by a positive pressure that discharges the concrete article on to a pallet and carrier 66 (Fig. 7). The filter paper protects the concrete surface. The carrier moves along an inclined rail 68 to deposit the pallet on intermittently moving endless chains 70 (Fig. 3 also), and returns upwards with a fresh pallet to receive the next discharged article. One or both major surfaces of an article are textured or given an exposed aggregate finish. Moulds and vacuum.-Each mould 20 is open-topped and over its base receives in succession a wire or plastics mesh (or the base is channelled to define a grid), an apertured plate, the filter paper and a second apertured plate acting as a template to give an embossed surface to the concrete. The vacuum is applied to the bases of two moulds by pipes wound in opposition on a drum, and is fed to the remaining mould bases by interconnecting pipes. One of the drum wound pipes includes a concentric pipe leading to a positive pressure source. Hoppers.-The hopper 48 includes a wire mesh base and pattern plate through which material is fed by reciprocated scraper blades (51) (see Fig. 10, not reproduced). Hopper 33 includes an upstream outlet that sprinkles cement through a scalloped plate, to prevent disturbance of the coloured cement, and a downstream outlet that applies cement in bulk to fill the moulds.