Production method for a concrete pillar or beam

Abstract: A production method for fabricating a concrete pillar or beam, in which method the concrete mix is sprayed against the wall of a mold (1, 2, 3, 4, 5) having a predetermined shape, after which the concrete surface is smoothed by levelling. The concrete surface is levelled with the help of a surfacing disc (6), whereby the pillar or beam is rotated so as to place one side of the pillar or beam at a time facing the surfacing disc so that the pillar or beam achieves a section of a square, rectangle, pentagon, hexagon, or a similar forn.

Description: The present invention concerns a production method for fabricating a concrete pillar or beam, according to which method the concrete mix is sprayed against the wall of a mold having a predetermined shape, after which the concrete surface is smoothed by levelling. With reference to Finnish patent applications 872244, (published 22.11.88)(& EP-A-292452, published 23.11.88) and 872245, (published 22.11.88), similar production methods have been previously disclosed for planar wall elements and for cylindrical pillars or beams resp. The aim of the present invention is to achieve advancements in this production method. AU-A-474397 refers to an apparatus for trueing concrete-clad pipes having a rotary brush arranged with its rotational axis substantially parallel to the axis of the pipe body. This means that the apparatus according to this reference can not produce a carefully levelled surface if the outer cross-section of the pipe body is not circular, as the surface of the trueing brush facing the pipe body surface has its rounded envelope surface in contact with the pipe body surface. The method in accordance with the invention is characterized in that the concrete surface is levelled with the help of a surfacing disc, rotatable about an axis being substantially perpendicular to the longitudinal direction of the pillar or beam, whereby the pillar or beam is rotated through equal fractions of 360° or indexed so as to place on side of the pillar or beam at a time facing the surfacing disc so that the pillar or beam achieves a section of a square, rectangle, pentagon, hexagon, or a similar form. Thus, with the help of the invention, pillar constructions with an appealing look are achieved that are readily transferrable and transportable by virtue of their hollow-core construction. Although the concrete pillar has a hollow-core structure, its compressive strength will be sufficient for a majority of applications. If necessary, the hollow core can be filled with concrete mix. An embodiment of the invention is caracterized by having the mold rotatable about its vertical axis and having a positional clamping facility for spraying and surfacing. This approach results in a quick production method for a concrete pillar, which is then transported for curing and hardening after spraying and surfacing. Another embodiment of the invention is characterized by having the mold placed in a horizontal rotator, and the rotator is used for turning the beam during production to alternately align three of the four sides of the beam facing the concrete spray gun and the surfacing disc so as to achieve a U-shape cored beam structure. This approach results in a cored beam structure, which has a predetermined structural strength and can be, when required, further steel-reinforced and filled with concrete mix at the construction site. A further embodiment of the invention is characterized by having the mold structure fabricated by winding plastic material, thin steel sheet or like material over elongated bars positioned so as to achieve a desired shape of the mold. The mold structure is further provided with, e.g., reinforcement fabric which offers improved adherence for the sprayed concrete mix prior to the surfacing operation. In the following, the invention will be examined in more detail by means of exemplifying embodiments with reference to the attached drawings, in which Figs. 1 and 2 show a cross-sectional view of a production method for a pillar with hexagonal cross-section. Figs. 3...8 show a production method for a beam structure with U-shaped cross-section. Fig. 9 shows the removal of a ready-cast beam structure from the rotator. Figs. 10...12 show cross-sections of different mold structures. Figs. 13...17 show a production method for a vertically aligned beam. According to the production method, concrete mix is sprayed against the walls of a mold 1, 2, 3, 4, 5 having a predetermined shape, after which the concrete surface is levelled. The concrete surface is levelled with the help of a surfacing disc 6 so by way of rotating the pillar or beam so as to place one side of the pillar or beam at a time facing the surfacing disc so that the pillar or beam achieves a desired cross-section. In accordance with the Figs. 1 and 2 as well as Figs. 13...17, the mold is rotatable about its vertical axis and has a positional clamping facility for spraying and surfacing. In accordance with Figs. 3...9, the mold 2 is placed in a horizontally aligned rotator 7, and the rotator is used for turning the beam during production to align three of the four sides of the beam facing the concrete spray gun and the surfacing disc apparatus so as to achieve a U-shaped cored beam structure. The cored beam and the mold are removed from the rotator 7 as indicated by arrow 8. Illustrated in Figs. 10 and 13 is a method for forming the mold structure using plastic sheet wound over thin bars 9. Bars 10 and wire 11 form a fabric structure, which provides adherence to the concrete mix. In accordance with Fig. 11, the mold can be formed from metal sheets 4 shaped as angle profiles. In accordance with Fig. 12, the mold is formed of angle steel profiles and elongated metal sheet strips 3.

Claims: A production method for fabricating a concrete pillar or beam, in which method concrete mix is sprayed against the wall of a mold (1, 2, 3, 4, 5) having a predetermined shape, after which the concrete surface is smoothed by levelling, characterized in that the concrete surface is levelled with the help of a surfacing disc (6) rotatable about an axis being substantially perpendicular to the longitudinal direction of the pillar or beam, whereby the pillar or beam is rotated through equal fractions of 360° or indexed so as to place one side of the pillar or beam at a time facing the surfacing disc so that the pillar or beam achieves a section of a square, rectangle, pentagon, hexagon or a similar form. A method as claimed in claim 1, characterized in that the mold (1, 5) is rotatable about its vertical axis and has a positonal clamping facility for spraying and surfacing. A method as claimed in claim 1, characterized in that the mold (2) is placed in a horizontal rotator, and the rotator is used for turning the beam during production to alternately align three of the four sides of the beam facing the concrete spray gun and the surfacing disc so as to achieve a U-shaped cored beam structure. A method as claimed in anyone of claims 1 to 3, characterized in that the mold structure is fabricated by winding plastic material, thin steel sheet or similar material over elongated bars positioned so as to achieve a desired shape of the mold.

Inventors: VIRTANEN OLLI, VIRTANEN, OLLI
Applicants: BETEMI OY
Application year: 1989
Main classification: B28B1
IPC codes: B28B1, B28B19, B28B21, B28B11