WO1993014287A1

WO1993014287A1 - Form for casting building elements

Info

Publication number: WO1993014287A1
Application number: PCT/AU1993/000004
Authority: WO
Inventors: Mariano Villaescusa
Original assignee: Di Cosmo, Patrick
Priority date: 1992-01-10
Filing date: 1993-01-08
Publication date: 1993-07-22
Also published as: AU1834692A

Abstract

A form for casting columns of concrete having a substantially square or other rectilinear cross section comprises a cardboard tube (5, 5') adapted to resist internal pressure, a waterproof skin (4, 4'), a mould cavity liner (8, 8') defining a mould cavity of square or other rectilinear cross section and disposed within the tube (5, 5'), and foamed plastics filler bodies (7) filling the spaces between the liner (8, 8') and the tube (5, 5'). In a preferred embodiment the tube (5') is split longitudinally and interengaging tongued and grooved plastics strips (14 and 15) are applied to the split edges for interengaging alignment thereof. The split is held closed by binding means such as adhesive tapes (13) wrapped about the tube (5').

Description

Invention Title: "FORM FOR CASTING BUILDING ELEMENTS"

The following statement is a full description of this invention, including the best method of performing it known to the Applicant:-

The present invention relates to the construction of building elements and in particular to a method and apparatus for casting a building element from concrete or other hard setting material.

The invention was devised primarily for use in the in situ casting of stanchions, plinths, columns or the like, and is described in relation to that usage hereinafter; but it will be appreciated that the invention is applicable to the casting of building elements generally.

Customarily concrete columns have been erected on site by constructing a form, of timber or of metal, to define the shape of a column, pouring a concrete mix into said form, allowing the mix to set, and then dismantling the form so as to strip it away from the finished column. Usually the timber or metal of the form is discarded. A separate form is constructed in situ for each column on a building site. This involves a considerable amount of heavy work and is a time and resource consuming task.

Columns of polygonal, square or other rectilineal cross-section have typically been erected using a form comprising flat panels and a supporting framework. Such framework is necessarily complex and heavy, to enable the panels to withstand the internal pressure created by the concrete mix poured into the form without bulging unduly. Consequently skilled tradesmen need to exercise care and precision in erecting such forms. Despite these precautions, builders still at times waste considerable resources repairing out of shape columns.

Further, because it is customary for such forms to be discarded once the concrete has set, it is desirable for them to be inexpensive insofar as materials are concerned, and for them to be able to be erected and removed from the cured concrete column expeditiously and with a minimum of skill and labour.

It is an object of the present invention to provide a form for casting a building element of concrete or like material which will alleviate at least one of the above mentioned disadvantages.

The invention achieves that object by providing a form wherein a mould cavity is at least partly defined by at least one filler body adapted to withstand compression, within and supported by a tube adapted to withstand hoop stresses.

According to one aspect the invention consists in a form for casting a building element comprising a tube and at least one filler body within and supported by said tube, and at least partly defining a mould cavity of smaller cross-sectional area than that of the tube.

Preferably said form further comprises a mould cavity liner. The liner may be in area contact with the inner surface or surfaces of said filler body or bodies, and constitutes a parting, preferably waterproof, membrane or layer between the concrete mix and the filler body or bodies. The liner may, for example, be comprised of polyethylene sheet material.

Usually the filler body, or each of them, is of substantially constant cross-section along the length of the form; but the filler body, or each of them, may taper to define correspondingly tapered mould cavities, if desired.

Preferably the outer surface of the, or each, filler body conforms to, and makes area contact with, the inner surface of the tube. That is to say, the, or each, filler body preferably has a cross-section of the same shape as the cross-section of a segment of the tube.

Alternatively, the filler body may be formed of a plurality of elongate segmental filler elements, with their edges integrally united to constitute a single body surrounding and substantially wholly defining the mould cavity.

The filler body, or each of them, is composed of a material adapted to take compression without substantial deformation. It may, for example, be expandable plastics material such as polyurethane foam or polystyrene foam.

SUBSTITUT The tube is comprised of a material adapted to resist and withstand the hoop stresses created in the tube by the internal pressure of the concrete mix poured into the mould in use. It may, for example be of condensed cardboard or a solid plastics material.

In a preferred embodiment the tube is split longitudinally to enable the form to be positioned to encircle pre-fabricated steel reinforcement, other than by sleeving it upon the reinforcement from one end thereof. In these instances, the tube is bound, wrapped or otherwise tied before concrete is introduced. That is to say, the form further comprises binding means, being pliable tensile elements encircling the split tube and adapted to withstand the hoop stresses created by the concrete mix poured into the form in use.

The longitudinal edges of such a split tube are preferably furnished with interengagable locating formations to ensure an accurate register therebetween.

The binding means may comprise a multiplicity of spaced parallel strips or tapes tensioned about the mould. Alternatively it may comprise a single adhesive tape or strap wrapped helically about the mould, or an adhesive wrapping film substantially covering the outer curved surface of the form.

A form incorporating a split tube may be opened, that is to say, the free longitudinal edges of the tube may be temporarily swung away from one another to permit the form to be positioned about steel reinforcement or the like. To that end, the tube may be sprung into the open position, or it may be formed with a fold line or other longitudinally extending hinge means, preferably diametrically opposite to the split. Once the

TITUTE SHEE reinforcement has been encircled, the form is swung closed from the open position and then bound. The corners of the mould cavity are then aligned with the building walls as required, and the form is then ready to receive the concrete mix.

For preference forms according to the invention are prefabricated at a dedicated site remote from the place of use.

The forms may be prefabricated in prescribed lengths, which may be used singly, or which may be used jointly to form longer columns. Alternatively they may be prefabricated in extended lengths that may be cut into shorter lengths as required on site.

Preferred embodiments of the invention further comprise an outer waterproof skin. The skin may, for example, be comprised of aluminium foil, plastics film, laminated film or like wrapping material, or may comprise a coating of paint.

Conveniently, external indicia or markings may be provided to indicate the position of a corner of the mould cavity, to facilitate correct alignment of the form in use.

Preferably forms including unsplit tubes further comprise stripping means adapted to facilitate peeling or otherwise stripping the form from a finished building element. The stripping means may, for example, comprise a stripping wire adapted to tear or otherwise cut the form, extending longitudinally within the said tube. More particularly, said stripping wire may be positioned within the mould cavity. For preference one end of the stripping wire is furnished with a hand grip means.

SUBSTITUTE SHEET Alternatively, or in addition, the stripping means may, for example, comprise a tear line pre-disposed into the support tube, in which case, binding means may be required.

According to another aspect the invention consists in a method of making a form for casting building elements according to the first aspect of the invention comprising the step of introducing at least one filler body into a support tube to define a mould cavity of smaller cross-sectional area than that of the tube.

Preferably the method of the invention further comprises the further steps of preparing a mould cavity liner, positioning the support tube to surround said liner to define a space or spaces between said tube and liner, and filling said space or spaces with a filler body or bodies.

By way of example, two embodiments of the above described invention are described in more detail hereinafter with reference to the accompanying drawings.

Figure^" 1 is a plan cross-sectional view of a form according to the invention.

Figure 2 is a longitudinal sectional view taken on the line 2-2 of figure 1.

Figure 3 is a scrap section of that part of figure 1 within the enclosure marked 3 drawn to a larger scale.

Figure 4 is a perspective view of the form of figure 1. Figure 5 is a perspective view of another embodiment of a form according to the invention, in an open position.

Figure 6 is an enlarged detailed cross-sectional view of the subject matter within the enclosure marked 6 in figure 7.

Figure 7 is a perspective view showing the form of figure 5 in a closed position.

The form illustrated by figures 1 to 4 comprises a support tube 5 of condensed cardboard furnished with a waterproof outer skin 4 of aluminium foil or aluminised plastics film, an octagonal mould cavity liner 8 of polyethylene material, and four filler bodies 7 of polystyrene foam material filling the spaces between the major panels of the liner 8 and the tube 5. The mould cavity liner 8 comprises four major panels defining a mould cavity of substantially square cross-section, and four minor panels effectively chamfering the four corners of the mould cavity. The filler bodies 7 are in area contact with the inner surface of the tube 5 and in area contact with the outer surface of the liner 8, so as to fill the spaces therebetween. Preferably the filler bodies 7 are expanded in situ, that is to say, within the spaces they fill in the finished form.

A stripping wire 9 extends for the length of the form, between one minor panel of the liner 8 and the tube 5. The wire 9 is secured at one end to one end of the tube 5 and its other end terminates in a hand grip 10. The wire 9 is adapted to tear or otherwise cut through the wall of the tube 5 to facilitate peeling or otherwise stripping the form from a finished concrete column. Figure 4 illustrates a form wherein the wire 9 has torn a substantially longitudinal slit 11 in the tube 5 extending partway along the length of the form from the top end thereof.

Indicia or markings (not shown) on the outer surface of the form may be applied so as to indicate the corner of the mould cavity.

The form illustrated by figures 5 to 7 is in most respects the same as the figure 1 embodiment, and corresponding parts are correspondingly referenced. The differences between the two embodiments are that the liner 8', tube 5' and skin 4' (corresponding to the liner 8, tube 5 and skin 4 of the figure 1 embodiment) are longitudinally split at 12, and, in use, the form is held closed by adhesive straps 13.

The longitudinal edges of the tube 5' are fitted with extruded plastics or like strips, namely a tongued strip 14 and a grooved strip 15, which interfit to ensure an accurate register between the tube edges.

Figure 5 illustrates the form in an open position. The longitudinal split 12 has been widened to permit the form to be positioned to encircle an article such as steel reinforcement other than by sleeving it upon the article from one end thereof.

A fold line 16 has been shown in tube 5', but in other embodiments the tube sides are merely sprung apart to widen the split.

In using this embodiment, once the concrete has cured the tapes 13 or other binding means are broken or removed to permit the form to be swung to an open position and to be peeled off the column. The form is reusable.

Briefly, in use, a form according to the invention is positioned about a steel reinforcement, bound, if of the split type, positioned with the reinforcement central of the mould cavity, the corners of the mould 9 cavity are positioned to the desired orientation «_ΠH * , by securing it to a floor TK ^{0πentatl0n an}<* the form is stabili

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A form for casting building elements of^" hard-setting material comprising a tube and at least one filler body within and supported by said tube, and at least partly defining a mould cavity of smaller cross- sectional area than that of the tube.

2. A form according to claim 1 wherein said form further comprises a mould cavity liner.

3. A form according to claim 2 wherein said mould cavity liner is in the form of a parting membrane adapted to provide a non-stick interface between the filler body or bodies and hard-setting material introduced into the mould cavity.

4. A form according to any one of the preceding claims wherein said mould cavity is of substantially rectilineal cross-section.

5. A form according to any one of the preceding claims wherein said mould cavity is of substantially constant cross-section along its length.

6. A form according to any one of the preceding claims wherein said at least one filler body has a cross-section that is substantially the same as the cross-section of a segment of the tube.

7. A form according to any one of the preceding claims wherein said at least one filler body is composed of expandable plastics materiaf.

8. A form according to any one of the preceding claims wherein said at least one filler body comprises a plurality of elongate filler elements,

their edges being integral and together defining a mould cavity of rectilineal cross-section.

9. A form according to any one of the preceding claims wherein said tube is composed of cardboard.

10. A form according to any one of the preceding claims wherein said tube has a longitudinal split along its length and wherein said form further comprises binding means to hold said split closed.

11. A form according to claim 10 wherein longitudinal edges of the split tube are furnished with interengaging locating formations to ensure an accurate register therebetween.

12. A form according to any one of claims 1 to 9 wherein said form further comprises stripping means adapted to facilitate peeling or otherwise stripping the form from a cured building element.

13. A form according to claim 12 wherein said stripping means comprises a stripping wire adapted to tear or otherwise cut the tube, extending longitudinally within the tube.

14. A method of making a form for casting building elements according to any one of the preceding claims comprising the step of introducing at least one filler body into a tube to at least partly define a mould cavity of smaller cross-sectional area than that of the tube,

15. A method according to claim 14 further comprising the further steps of preparing a mould cavity liner, positioning the tube about said liner to define at least one space between said liner and said tube and introducing at least one filler body into said space so as to fill it.

16. A method according to claim 15 wherein said step of introducing at least one filler body into said space is effected by expanding a foamable plastics therein.

SUBSTITUTE SHEET_