Procedure for the Production of Concrete Elements

The present invention relates to a procedure for the production of concrete elements, whereby the element is shotcreted using a shotcrete gun.

In current practice, the concrete elements needed for building purposes are cast in various moulds. The moulds, which are usually held in a horizontal position, are filled with fresh concrete, which is then allowed to harden in the mould. The necessary reinforcements and isolation materials are placed in the moulds either before or during the casting operation.

The object of the present invention is to achieve a new type of procedure for the production of concrete elements. The procedure of the invention is characterized in that a vertically placed wal structure, such as a sheet or board of insulating material with concrete reinforcement, is shotcreted. The invention renders casting moulds superfluous, because a sufficiently even concrete layer of the desired thickness can be formed directly on the vertical wall structure. The element can be easily moved and manipulated when the concrete is still fresh, because it is light and no moulds are needed. The surface of the element is visible all the time, so that any defects can be easily mended. The surface of a casting in a mould cannot be seen and defects are always more difficult to repair after the element has been removed from the mould.

A preferred embodiment of the invention is characterized in that the wall structure, suspended from rails by means of supporting arms, is moved along the rails at the same time when it is shotcreted by a shotcrete gun moving in the vertical direction. Thus the wall structure can be easily moved back and forth while the shotcrete gun advances from the bottom edge upwards, so that an even concrete layer of the desired thickness is formed. The supporting arms are detached from the element and used again.

Another embodiment of the invention is characterized in that the shotcrete gun is moved on separate rails running in a direction perpendicular to the direction of movement of the wall structure. The shotcrete gun being movable in this manner, the distance to the wall structure is short, which makes it possible to use very stiff fresh concrete that will stick to the wall structure without dripping off. Previously known shotcrete guns use very loose fresh concrete because they need hoses to transfer it to the target.

A preferred embodiment of the invention is further characterized in that, after the element has been shotcreted, the concrete surface is smoothed by mechanical means, i.e. treated with an incisor which is moved in the vertical direction e.g. at the same time when the element is moving in the horizontal direction.

A preferred embodiment of the invention is further characterized in that the concrete surface is smoothed by mechanical means, i.e. treated with a lapping disc rotating around its axis, the disc being likewise moved up and down as the element is moving back and forth.

A preferred embodiment of the invention is further characterized in that the concrete surface is smoothed by mechanical means, i.e. treated with a brush moving up and down as the element is moving back and forth.

With all the above-mentioned embodiments designed for finishing treatment, the desired appearance of the concrete surface can be achieved by simple means, because the surface is sufficiently fresh immediately after the shotcreting.

A preferred embodiment of the invention is further characterized in that a conveyor is provided below the element to collect and remove the extra concrete falling down during shotcreting or surface treatment. The amount of this extra concrete accumulated during the treatment is fairly large, so it can be removed with a belt conveyor and reused while it is still fresh.

A preferred embodiment of the invention is further characterized in that the incisor consists of a tightened band or wire which is vibrated and/or run around a continuous track as in a bandsaw when the concrete surface is being cut. In this manner, the whole surface of the element can be evened with a single operation.

A preferred embodiment of the invention is further characterized in that the form of the cutting edge of the incisor is adjusted by means of intermediate supports to produce different shapes. Thus the concrete surface can be shaped in various ways and even a round column can be given the desired appearance and form.

In the following, the invention is described by the aid of an example, reference being made to the drawings attached, wherein:

FIG. 1 illustrates the procedure for the production of concrete elements and the apparatus implementing it, seen from the side.

FIG. 2 shows a section through FIG. 1 along the line II--II.

FIG. 3 illustrates the surface treatment of an element of a circular form.

FIG. 4 represents a bandsaw-type concrete incisor.

By the present procedure, the concrete element is produced by shotcreting a vertically oriented wall structure 1 consisting of a board 2 of insulating material provided with concrete reinforcement 3 on its surface. The wall structure 1 is moved back and forth as shown by the arrow 4 while fresh concrete is sprayed directly onto the wall structure 1 by a shotcrete gun 8 moving in the vertical direction as shown by the arrow 7. The wall structure 1 is suspended from rails 6 by means of supporting arms 5. The shotcrete gun 8 is moved along separate rails at right angles to the direction of movement of the wall structure. After the shotcreting, the fresh concrete surface of the element is treated with an incisor 10, a rotating lapping disc 11 or a brush 12 as required. Below the element is a belt conveyor 13 placed so that it will receive and take away the superfluous fresh concrete falling down during shotcreting and surface treatment. In FIGS. 3 and 4, the incisor consists of a tightened band 14 or wire 15 which is vibrated or run around a continuous track as in a bandsaw when the concrete surface is being cut. The form of the cutting edge of the incisor in FIG. 3 can be adjusted by means of intermediate supports 16 e.g. to shape a column.

It is obvious to a person skilled in the art that the invention is not restricted to the examples described above, but that it may instead be varied in the scope of the claims to follow. Thus the procedure may employ e.g. profiling tools to produce brick wall patterns or the like. The incisor may also consist of a rigid straight plate with a knife-like sharpened edge, which can also be bent into a desired form.