AU675945B2 - Sacrificial collapsible isolation void forming formwork systems - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT e S. *C S.

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Name of Applicant: Actual Inventor: Address for Service U Mtocx Mtag3 occ, Invention Title: F J MANCER TRADING CO PTY LIMITED Frederick Joseph Mancer emC eenbr., 143 dreRo- Failiht Sdne NB---94- -oipd7A The following statement is a full description of this invention, including the best method of performing it known to us: -2- This invention relates to improvements in the design, manufacture and installation of fibre board void forming elements. Void forming elements are used in the construction industry to form a void within a concrete structure or an isolation void between a concrete structure and the ground the structure is built on.

Voids within a concrete structure reduce the quantity of concrete within the structure, thus reducing the weight and cost of the concrete.

Isolation voids help prevent damage to a structure due to reactivity and mine subsidence (movement of the ground the structure is built on). They also help prevent damage caused by sound vibration and vibration of the ground.

An economical way to form an isolation void is by the use of a plurality of three-dimensional fibre board elements placed end to end and side by side or otherwise as required on the prepared surface of a construction site thus forming an overall layer that concrete may be poured upon. The concrete sets and hardens gains strength and becomes self supporting and load bearing whilst in most cases the layer of void forming elements eventually deteriorates leaving a void between the concrete and the underlying ground.

Although this method of creating isolation voids is known, many of the prior art systems suffer disadvantages. In particular, S some require special waxed board and nonstandard components, which increase the cost of the void forming elements. Even more importantly, the prior art systems do not deteriorate as Sswiftly as desired in many situations.

The void forming element of the present invention is economical because it can include standard manufactured components used in the packaging industry. In addition, the components for the element of the invention may be delivered to a construction S site in disassembled form, thus reducing both delivery and 24/12/96 15:2" C11C CENTRE 06 2011041 [1004 -3storage costs. Further, the elements of the present invention may be quickly assembled by unskilled persons. if desired, the elements can, of course, be delivered fully assembled. In addition, the element of the present invention has open ends to permit admission of water and enhance deterioration of the element.

Accordingly, this invention provides a sacrificial, collapsible void forming element comprising a core and an outer casing, which has four sides and two opposed open ends, the core being contained within the four sides, wherein the outer casing is formed from a rectangular or square blank having score lines defining either four or five panels which form the four sides.

In a particularly preferred embodiment, the blank has score lines defining five panels, the second, third and fourth panels forming three of the four sides and the first and fifth panels forming the fourth side, either by abutting or overlapping, partially or completely.

In another preferred embodiment, the blank has score lines defining four panels, the first, second, and third panels forming three of the four sides and the fourth panel abutting the first panel to form the fourth side.

The outer casing is preferably rectangular but may be square and-may be made of any suitable material, having regard to the purpose of the void forming element, which must be able to collapse over time after pouring of a concrete slab. A preferred material is corrugated inner cell paper fibre board.

The core is preferably a honeycomb structure of fibre board or similar material, such as the partitioning commonly used to separate bottles and the like in bottle boxes. if the depth of the element is to be increased, the core may have two or more stages separated, for example, by intermediate layers of sheet fibre board.

-4- The main purpose of the core is to add strength to the element of the invention. The core should preferably be degradable under the conditions of intended use, namely, after the concrete gains designed strength and is load supportive, although for some applications it is desirable to use a core made from a slab or slabs, or even loose chunks, of a low-cost material such as polystyrene.

The outer casing is typically formed from one sheet of fibre board although for especially large panels it may become necessary to join one or more sheets.

In the embodiment having five panels, it is desirable for the first and fifth panels to overlap, to facilitate fixing of the first panel to the fifth panel, for example, by adhesives, mechanical fasteners or other known methods of fixing. For added strength and load-bearing value, it is preferred that the first panel overlaps the fifth panel completely. However, this invention also contemplates the situation where there is no overlap, the first and fifth panels simply butting together, being fixed by tape or other suitable means. This embodiment will differ from the embodiment with four panels, where the abutment occurs between one side and another, rather than on a single side.

If desired, a reinforcing material such as compressed fibre board or the like may be inserted inside the outer casing, so that it will lie above the core in use.

If desired, additional fibre board partitions may be vertically arranged inside the outer casing such that in use they provide reinforcement between the top and bottom sides.

Alternatively, the reinforcing material (if used) may be located outside the outer casing, on top of the element in use.

As an option, the void forming element of the invention may be inserted in a water-impervious envelope, made for example, of -V 4 24/12/96 15:27 CMiC CENTRE, 4IeOI 2013,841N.78r0 NO. 1?20 polythene sheeting or sheeting lined with bitumen. The envelope should be able to admit water, for example, through an opening therein, so that degradation of the element can occur over time after installation. The purpose of the envelope is to retard premature degradation of the element during storage on site and on initial installation.

Alternatively, a water-impervious sheet can be included within the outer casing adjacent either the top or bottom side. in either case, in use, the elemient should be laid such that the side having the sheet is closest to the earth. The inclusion of a water-impervious envelope or sheet in its different arrangements is intended to allow the user to suit a element to the moisture conditions of a particular construction site.

To allow for greater control over the useful life of the voia forming element of the invention, a water induction pipe can be included 6o that the element can be destroyed by water saturation once it is determined that the concrete has set and become load bearing.

Whilst the elements of the invention may be 'assembled prior to delivery, the components of the elements of the invention may be transported efficiently and it is therefore preferred that the void forming elements of the invention may be made up on site. Accord-ingly, this invention also provides a method of constructing a void forming element, comprising the steps of: placing a formed core on a square or rectangular blank having score lines defining first, second, third and fourth panels; (ii) folding the blank along thie score lines to form an outer casing having first, second, third and fourth sides, with two opposed open ends, the core being contained within the four sides; and (iii) securing the first and fourth panels so that they abut.

24112196 15:27 C2ML NXITIC 4* (i1C 44-31,14 N0,741-1 ('006 This invention provides a further method of constructing a void forming element, comprising the steps of: placing a formed care on a square or rectangular blank having score lines defining first, second, third, fourth and fifth panels; (ii) folding the blank along the score lines to form an outer casing having first, second, third anTd fourth sides, with two opposed open ends, the core being contained within the four sides; and (iii) securing the first and fifth panels.

Preferred embodiments of the invention will now be described in connection with the drawings in which: Fig. 1 shows a general perspective of a partly assembled void forming element embodying the invention with part only of the core in place.

Fig. 2 shows the outer casing of the element shown in Fig. 1 bef ore folding along its score lines; Fig. 3 shows the full core of the element shown in Fig. 1; Fig. 4 shows the element of Fig. 1 after the outer casing has been closed.

Fig. 5 shows a second embodiment of the outer casing; Fig. 6 shows a third embodiment of the outer casing; Fig. 7 shows in plan view an open element where the core includes additional support members; Fig. 8 shows part of the core shown in Fig. 3; Fig. 9 shows an alternative core-forming part; Fig. 10 shows the layout of a number of void forming elements placed on a sand levelling layer on a construction site; Fig. 11 shows in section the layout of elements where a concrete floor slab is to include an internal beam; Fig. 12 shows a cross-section of a prepared construction site with elements in place; Fig. 13 shows the prepared construction site of Fig. 12 in plan view; Fig. 14 shows a part cross-section of a void forming element sitting on a sand levelling layer and overlaid with concrete which includes a fluid injection pipe penetrating the upper surface of the element; e Fig. 15 shows a running bond arrangement of elements overlaid with reinforcing material.

In Fig. 1 there is shown generally at 10 a void forming element .oeo S.:0 according to the invention. It consists of an outer casing 11 and two identical core pieces 12a, 12b (12b not shown). As shown in Fig. 2, the outer casing 11 is composed of a single piece of fibre board, either solid or corrugated inner cell sheet, with four scores (creases) at required positions to assist in folding it to form a rectangular tube.

For larger panels, it is sometimes necessary to join two pieces S of fibre board to make outer casing 11. In that case, it is typical for the pieces to be butt-joined and tape-fixed along side 16 as shown at 23 in Fig. 6. A butt joint is also suitable when the element of the invention has a casing with only four sides.

-8- The two core pieces 12a, 12b are shown in greater detail in Fig. 3 and consist of an assembly of identical and interlocking corrugated fibre board partition pieces 13 similar to the division partitions within packages for bottles. A typical partition piece 13 is shown in greater detail in Fig. 8. It has six equidistantly spaced slots allowing twelve like pieces 13 to form a six-by-six lattice core piece such as 12a or 12b.

In Fig. 9, an alternative partition piece 13 is shown with five slots. Ten like pieces 13 allow a five-by-five lattice core to be formed. Such a core may be sufficient when the element has to bear a lighter load. It will be appreciated that, depending upon their application, pieces 13 may be of any desired length and include any number of slots. Equally, it will be understood that a single core piece, constructed by a like method, may be used instead of two separate core pieces.

The invention is not limited to a void forming element having a core of the kind just described. Whilst one advantage of the o present invention is to provide for a void forming element which deteriorates upon water saturation, cores made from polystyrene slabs or chunks are also favoured because of the low cost of that material together with its known load bearing eeoo characteristics.

Further, the core may have two or more stages to give depth and Sr strength to a larger void forming element. Core pieces 12a and 12b may, for example, be stacked with like pieces to form a two-tier core. It is preferable for the stages to be separated by a sheet of fibre board. Generally a larger void forming element of this kind would require an outer casing 11 joined as shown in Fig. 6 as previously described.

Outer casing 11 is folded along its score lines to form a case for core pieces 12a, 12b and has first, second, third, fourth and fifth panels numbered 14, 15, 16 r 17 and 18 in Fig. 2 and throughout the drawings where relevant. Core pieces 12a, 12b STF are placed upon the inner surface of panel 16 whereupon the -9void forming element is closed by the inward folding, first, of panel 18 overlapping panel 14. The element 10 can be secured in this closed position by the use of known means such as staples or adhesive tape.

The substantially complete overlap of panel 18 by panel 14 increases the structural rigidity of element 10 and allows a user the option of placing the overlapped surface 14, 18 to the top when greater load bearing strength is required, and the overlapped surface 14, 18 to the bottom when construction site conditions are especially wet.

It will already be understood that, within the scope of the invention, variations to void forming element 10 are contemplated which allow for greater or less rigidity. The same variations allow for a differential in the cost of the Spanels which has further advantages to users.

As one option, Fig. 5 shows a further embodiment of outer casing 11 in which the overlap of panel 18 by panel 14 is relatively minor. Such an element can be produced more economically.

In Fig. 7, core pieces 12a, 12b are shown laid in place on panel 16 before folding and closure of outer casing 11 and in addition to which additional support partitions 19 are vertically arranged between, and at either end of, core pieces 12a, 12b to give greater internal strength to element Other embodiments are possible. Instead of, or in addition to, support partitions 19, a flat fibre board sheet similar in dimensions to panel 16 may be placed over the top of core pieces 12a, 12b before element 10 is folded and closed.

A further option which allows for greater control over the life of the element 10 is explained with reference to Fig. 14.

4 Element 10 can include a hollow conduit pipe 20 through which a 3 ;liquid such as water can be passed. The pipe 20 is of such a length that its inlet end sits above the level of poured concrete and its exit end directs water immediately to the core pieces of element 10. Once the poured concrete has set and become load supporting, water can be injected down pipe guaranteeing the deterioration of element As a further alternative, element 10 can after closure be completely enveloped within a water impervious membrane such as sheet plastic. Again, the addition of that membrane would retard deterioration of element 10 and this embodiment would have particular application in especially wet construction site conditions. It is of course not necessary for a water impervious sheet to envelope the finished element 10 and it is contemplated that a sheet of plastic sized to approximate the dimensions of panel 16 could be placed on the inner face of S panel 16 before core pieces 12a, 12b are set in place, or on top of core pieces 12a, 12b before panels 18 and 14 are folded Sinto a state of closure. In either case, it is contemplated S that the element 10 should be laid such that the plastic sheet is closest the side adjacent the earth and, depending on site conditions, this may or may not be the side which has the overlapped surface 14, 18.

Figs. 10 to 15 show the invention in use. In Fig. 10, elements 10 are laid on a sand sub-base at a construction site. In general terms there are two preferred ways of laying out a plurality of elements 10; either in running bond arrangement or o in basket weave arrangement.

Fig. 11 shows in cross section an arrangement of elements which might be used where a concrete floor slab is to include an internal beam.

Figs. 12 and 13 show in cross-section and plan, respectively, a construction site where a number of elements 10 have been laid out in running bond fashion ready for pouring of the concrete.

SThe position of concrete piers is denoted by reference numeral 21 and the site has a trench 22 around its perimeter.

-C)i 2 -11- In use, it is unnecessary for every element 10 to have a water injection pipe 20 (if used); as shown in Fig. 13, a small number may only be needed to ensure saturation of a plurality of elements 10. Note that in Fig. 13 the positioning of the pipes 20 is identified by numeral 24 which is a square plastic plate shown in greater detail in Fig. 14 and the purpose of which is to keep pipe 20 stable and erect under the pressure of concrete pouring. Typically, the underside of plate 24 is glued to the outer surface of panel 14.

Should an additional load bearing and impact resistant working surface be required, large sheets of medium density fibre board may be installed over elements 10 as is shown in Fig. 15 and fixed in position by mechanical fasteners or adhesives.

It will be recognised that numerous other modifications and variations will be apparent to a person skilled in the art as i falling within the scope of the invention.

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Claims (4)

1111-YrIli I'MY -12- The claims defining the invention are as follows:- 1. A sacrificial, collapsible box-like void forming element comprising a core and an outer casing which has four sides and two opposed open ends, the core being contained within the four sides, wherein the outer casing is formed from a rectangular or square blank having score lines defining either four or five panels which form the four sides.

2. A void forming element according to claim 1, wherein the blank has score lines iefining five panels, the second, third and fourth panels forming three of the four sides and the first and fifth panels forming the fourth side.

3. A void forming element according to claim 2, wherein the first and fifth panels abut.

4. A void forming element according to claim 2, wherein the first and fifth panels partially overlap. A Void forming element according to claim 2 wherein the first and fifth panels completely overlap. 6. A void forming element according to claim 1, wherein the blank has score lines defining four panels, the first, second, and third panels forming three of the four sides and the fourth panel abutting the first panel to form the fourth side. 7. A void forming element according to any one of clainiz 1 to 6 wherein the outer casing is made of corrugated inner cell paper fibre board. 8. A void forming element according to any one of claims 1 to 7 wherein the core is a honeycomb structure fibre board. 9. A void forming element according to any one of claims I to 7 wherein the core is comprised of chunks or a slab of RA4 olystyrene. 011( 1 1 HIM (if, 011 If fill lAf 1. '411 1101 -1 -13- A void forming element according to any one of claims 1 to 9 wherein a layer of reinforcing material is provided inside the outer casing between the four sides and the core. 11. A void forming element according to any one of claims 1 to wherein one or more partitions are included within the outer casing.- 12. A void forming element according to any one of clais 1 to 11, when placed inside a water-impervious envelope. 13. A void forming element according to any one of claims 1 to 11 wherein a water-impervious sheet is placed inside the outer casing between at least one of the four sides and the core. 14. A method of constructing a sacrificial, collapsible void forming element comprising the steps of: placing a formed core on a square or rectangular blank having score lines defining first, second, third and fourth panels; (ii) folding the blank along the score lines to form an outer casing having first, second, third and fourth sides, with two opposed open ends, the core being contained within the four sides; and (iii) securing the first and fourth panels so that they abut. A method of constructing a sacrificial, collapsible void forming element comprising the steps of: placing a formed core on a square or rectangular blank having score lines defining first, second, IA4" third, fourth and fifth panels; t (ii) folding the blank along the score lines to form -14- an outer casing having first, second, third and fourth sides, with two opposed open ends, the core being contained within the four sides; and (iii) securing the first and fifth panels. 16, A method as claimed in claim 15, wherein the first and fifth panels are secured by forming a butt joint between the first and fifth panels. 17. A method as claimed in claim 15, wherein the first and fifth panels are secured by overlapping part of the first panel with part of the fifth panel and providing adhesive to the overlap. 18. A method as claimed in claim 15, wherein the first and fifth panels are secured by overlapping all of the first panel with all of the fifth panel and providing adhesive to the overlap, 19. A sacrificial, collapsible void forming element substantially as herein described with reference to Figures 1 to 4 or 5 to 6 or 7 of the accompanying drawings. A method of constructing a sacrificial, collapsible void forming element substantially as herein described with reference to Figures 1 to 4 or 5 to 6 or 7 of the accompanying drawings. Dated this eighteenth day of December, 1996 F aT MACER TRADING CO. PTY LTrD By Its Patent Attorneys R A 4,1,CHRYSILIOU MOORE MARTIN li III LI'[h 4 1,1i 01 I Ij. ABSTRACT The invention provides a sacrificial, collapsible box-like void forming element which has a core and an outer casing. The outer casing has four sides and two opposed open ends. The core is contained within or embraced by the four sides. The outer casing is formed from a rectangular or square blank having score loines defining either four or five panels which S form the four sides. The open ends of the void forming element can enhance deterioration of the void forming element after the void has been formed.