METHOD TO PRODUCE PIECES OF CONCRETE Russian patent published in 1997 - IPC

FIELD: production of building materials and structures, production of panel building blocks, flat and spatial structures made out of cellular and monolithic /heavy-weight, lightweight concrete in particular. SUBSTANCE: aim is to make production process simpler and cheaper, to ensure high quality of pieces surfaces, to increase pieces strength and frost resistance. To realize the aim metal formwork is prepared, polymeric film is placed loose in it so, that to create hermetical without breaks in places of formwork joints shell, plastic concrete mixture is cast, its surface is covered with film so, that to create closed shell, cast mixture is compacted by vibration under overload. Then preliminary holding is exercised till concrete achieves density equal to 0.1 - 0.2 % of mark density and piece is finely hardened in medium of saturated steam or air. Polyethylene, cellophane, polyvinylchloride, polypropylene, polyamide, fluoroplastic film is used. Final hardening is exercised in formwork and film under overload and normal pressure in electric or induction or gas furnaces or using electric current passing through metal formwork or electrodes or using infra-red heaters in compliance with cyclogram: heating up to 85 - 95 C for 1 - 4 hours, isothermal holding for 6 - 15 hours, uniform cooling for 1 - 3 hours, following holding of piece in formwork under temperature of medium over 18 C for 2 - 3 hours. In other version after preliminary holding piece in film without formwork is hardened in autoclave under temperature exceeding temperature of film melting or piece without formwork and film is hardened in autoclave or in steaming chamber. EFFECT: simplified and cheaper production process, high quality of pieces surfaces, increase pieces strength and frost resistance. 3 cl, 7 dwg