LV14308B - Technological process for formation of thin wall concrete shells - Google Patents

Abstract

The invention is related to ceiling and roof constructions of buildings, and it can be used for production of concrete and fiberconcrete shells in construction engineering. The offered process is characterized in that a formwork is made out of elastic deformable material (rubber layer) having the ends fixed to the rigid frame. Size and shape of the frame correspond to the horizontal projection of the shell produced. Thickness of the frame complies with the thickness of the shell. The mould is located on the horizontal surface, filled by concrete or fiberconcrete, compacted and evened. After that the formwork fulfilled by concrete is lifted up and kept in this condition till the moment when concrete has hardened and its deformed shape, raised by deadweight of concrete and formwork, has been stabilized. After that the shell is demolded. The bottom part of the shell can be reinforced by flexible material, for example, glass fiber net, placing it on the formwork surface before filling in the concrete mix or placing it on the upper shell's surface and pressing it into the concrete upper surface layer.

Description

The invention relates to the construction of roofs and ceilings of buildings and to the technological processes of their creation. Its field of application is the manufacture and assembly of prefabricated thin-walled liners for concrete, reinforced concrete and fiber-cement.

There is a known process / 1 / for the production of concrete shells, in which the fabric is folded in various ways, fixed, manually applied to the embossed concrete mixture and then cured. The shell is rendered by separating the fabric template from the concrete surface and acquires architectural elements with different reliefs.

There is a known process / 2 / for the production of concrete shells, according to which, according to architectural requirements, the fabric is self-weighted, sprayed with a mixture of concrete, then hardened and the liner separated from the mold.

The technological process for making concrete liners is known / 3 /, according to which the canvas mold is allowed to hang at various points or lines under its own weight, then the inner surface of this formwork is hand-coated with a concrete mixture layer and hardened. The resulting liner is then stripped by separating it from the fabric mold.

These known technological processes have the following disadvantages;

1) During the concreting process, it is not possible to control and ensure the thickness of the concrete mix layer.

2) it is very difficult to level and polish the upper exposed surface of the laid layer upon completion of the concreting process, which usually results in quite complicated or creased processes using the described processes; uneven traces of technological operations and non-conforming trace geometry remain on the upper surface.

The technological process for the production of concrete shells / 3 / is known, whereby a mixture of concrete or fibrous concrete is applied on a non-inflated and leveled pneumatic mold and leveled. Then, before the concrete begins to set, the air is pumped into the mold, raised to the specified shell size, hardened and rendered. The disadvantage of this technique is the cumbersome technological process, which requires ensuring the airtightness of the formwork, the necessity of a compressed air compressor and ensuring constant pressure during concrete curing.

The object of the invention is to provide a technological process for the formation of concrete shells which does not have the disadvantages of known technological processes. To achieve this goal, an innovative technological process is proposed that includes the following operations:

- preparing a frame of solid material corresponding to the horizontal projection of the shell to be formed and having a height corresponding to the thickness of the shell to be formed;

- a sheet of flexible material, eg of rubber or synthetic fibers, of dimensions corresponding to the horizontal projection of the liner to be formed is attached to the lower edge of the frame;

- the frame, together with the sheet of elastic material attached to it, is placed on a horizontal surface, eg on a table;

- the bottom layer of the liner is reinforced, if necessary, with a mesh of a flexible material, such as fiberglass or synthetic material, before being applied to the mold described in claims 1 to 3, of a flexible material, such as rubber, before concreting. , flat surfaces of the formed floor;

- Apply a layer of concrete or fibrous concrete with a thickness corresponding to the shell thickness to the flat surface of the prepared formwork, seal it and level it;

- the upper layer of the liner, if necessary, is reinforced with a mesh of flexible material, applied to the fresh concrete surface laid and pressed into it, eg by a roller;

- if necessary, the upper surface of the concrete to be inclined;

- when the concrete mixture is in a plastic state, the formwork is gripped by the frame before the start of the curing process and lifted together with the concrete layer filled into it, allowing the elastic material floor and its concrete layer to hang in a curved position as far as properties and the diffuse load caused by the weight of the fresh concrete layer laid on it;

- the raised formwork, together with the convex concrete layer, is placed on supports that are placed under the formwork frame;

- harden the liner to prevent deformation of the mold;

- after hardening of the shell, it is revealed by lifting it out of the mold;

- when the shell is designed to be convex upwards, it is rotated 180 °, transported and assembled on site, whereby the liner can also be trimmed before shaping, with the mold and supporting it on a horizontal surface; then the mold is lifted, the liner is transported and assembled on site.

Today's prefabricated reinforced concrete technology uses solid metal or plastic molds for shell formation. Such molds are labor-intensive and expensive to produce due to their complicated two-way curved surfaces. Their use in the manufacture of folding liners, unlike the process proposed, is technologically inflexible and requires a higher capital investment.

Unlike pneumatic molds, whose surface geometry is determined by the radial pressure of the intake air, the proposed technique allows the liner to be given a geometry that corresponds to the trajectories and distributions of the main compressive / tensile stresses exerted vertically on the shell surface under load. This is much closer to the real stress-free orientation of the main stresses, without bending moments, and allows the shells to be thinner, lighter and cheaper. By folding the mold down, the mixture is slightly compressed and this reduces the likelihood of early cracking of the mixture.

Sources of information:

1. Heinz Isler, The Engineer’s Contribution to Contemporary Architecture. John Chilton, RIBA Publications, Tom Telford Publishing, London 2000, p.32, 46

2. Thin Shell Concrete from Fabric Molds. C.A.S.T. The Center for Architectural Structures and Technology. University of Manitoba, Faculty of Architecture, prepared by Mark West, 2009.

3. Robert P.Schmitz, P.E. Fabric Forms of Architectural Concrete, Ooncrete Plant International, Issue 3 (June / July) 2010.

4. Latvian patent no. No. 14277, issued May 20, 2011, to U.S. Patent Application No. P-10-162, "Technology Process for Concrete Shell Formation," dated November 30, 2010;

authors of the play V-Ā Iosa and A.Krasnikovs

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Claims

Claims (4)

Claims 1. The process of forming thin-walled concrete liners, comprising forming, preparing concrete mixture, applying to the surface of the formwork, sealing, curing and forming, characterized in that it comprises preparing a formwork from an elastic material, such as a rubber sheet, attaching the edges of the sheet. placing a mold on a horizontal surface, placing a concrete or fibrous concrete mixture in a mold, sealing and leveling, lifting the filled mold to stabilize its deflection due to weight, to a frame of a size and shape corresponding to the horizontal projection of the molded shell and to a thickness of the molded shell; concrete hardening and shaping. The process for forming thin-wall concrete liners according to claim 1, characterized in that a reinforcing material of flexible material, such as a fiberglass mesh, is laid under the surface of the formwork before applying the concrete mixture layer. The process of forming thin-wall concrete liners according to claim 1 or 2, characterized in that after laying the concrete mixture layer and before raising the formwork, a reinforcement of a flexible material, eg a fiberglass mesh, is applied and imprinted thereon. . The process of forming a thin-walled concrete liner according to any one of claims 1 to 3, characterized in that, after hardening of the concrete, the liner is turned upside down, then lifted, transported and assembled at the site.