AU737849B2 - Improvements relating to foundations or footings, suspended floors or ceilings - Google Patents

Description

48655 HKS/BM P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: NICOLA LEONARDIS SActual Inventor(s): NICOLA LEONARDIS Address for Service: COLLISON CO.,117 King William Street, Adelaide, S.A. 5000 Invention Title: IMPROVEMENTS RELATING TO FOUNDATIONS OR FOOTINGS, SUSPENDED FLOORS OR CEILINGS Details of Associated Provisional Applications: PP1241 Dated 6th January 1998 PP1784 Dated 11th February 1998 The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 This invention relates to foundations or footings, suspended floors, ceilings or the like where the footing, ceiling or floor or the like is to be formed from concrete with use of lost formwork.

I have previously invented a corner spacer which is currently used in conjunction with rectilinear lost form work elements such as cardboard boxes or polystyrene blocks or boxes where spacers hold these elements in spaced apart alignment by holding corners of the elements during the pouring of the concrete. Sometimes this method of construction is referred to as a waffle pod 1 0 construction.

The problem to which this invention is directed will now be described with respect to footings but it is to be clear that the same problems apply to other applications such as suspended floors and ceilings.

o The use of a corner spacer where the spacer extended into each of adjacent channels between adjacent rectilinear elements provided a substantial improvement in the way that lost formwork in waffle pod constructions were being held.

I have observed that with some lost formwork elements (pods)that these are bein g dislodged or shifted during the pouring of the footing process to an extent that a poured beam will be wider than necessary subsequent to the e footing being poured. Because footings using this process are surrounded by a perimeter of fixed dimensions, this can result in at least one if not more of channels between elements being of lesser width than has been planned or may be desirable.

Building codes conventionally require a selected thickness of concrete around 3 0 reinforcing rods and if this is less than the code requires, then serious consequences can result for instance the foundation can be condemned or in order to allow for this problem, an excess concrete may be required overall which can significantly add to the cost of a footing.

3 5 The challenge however has been to find out what has been causing this problem because conventionally, after a footing has been poured, it is very difficult subsequently to examine the area within the concrete or beneath the concrete.

I have discovered that this problem is especially occurring when spacers of conventional design as they currently exist are being used with lost formwork elements of generally rectilinear shape but where these formwork elements have an outwardly curved or convex shaped corner.

Such a corner has been found to have advantage in reducing stress concentration in a subsequently poured footing. Such a shape can be easily achieved by making lost formwork elements from a foamed plastics material such as foamed polystyrene which is moulded with this curved corner shape.

The spacers as they are currently being produced have, for each corner, two faces defining between them a 900 corner, each face having respective planar surfaces that will be positioned in use so that a respective surface is lying in contact with a respective side of a corner of one of the lost formwork elements.

This implicitly then will leave an open area between a curved shape of the lost 1 5 formwork and the internal corner of that part of the spacer.

I have found out therefore what is causing the problem.

This is that when concrete is poured over a spacer holding the lost formwork S 2 0 with a curved corner, some of the concrete will obviously go into the gap between the spacer corner and the outer curved surface of the element and ;because concrete includes aggregate, and such aggregate can be of tapered "shapes.

When the concrete is forced or vibrated into position the aggregate is forced O between the respective faces that is on the one hand the faces of the spacer, and on the other, the lost formwork element, and they are simply pushed apart by a wedging action of the aggregate.

3 0 Such a result then can cause shifting which can lead to a minor or major dislodgment. In either case however, the effect can be cumulative as the foundation or footing is progressively poured with the result that at the end of the pour, the channels defined by the respective lost formwork elements at the end of the pour can be significantly smaller than when set up initially.

An object of this invention is to reduce this problem by providing an apparatus or a method that will assist in this.

This is to arrange that the shape of adjacent surfaces to any lost formwork will be such as to exclude concrete between the facing surfaces or have such a distance apart that the size of any aggregate extending between them will no longer have a wedging and therefore displacement effect when being pushed into position.

In one form of this invention then, this can then be said to reside in a spacer for holding apart by engaging at or close to the corners of each of at least two lost formwork elements each of the elements being generally rectilinear in outermost dimensions with at least one curved corner, the spacer including engaging surfaces adapted to engage against both sides of a curved corner of a first of the elements and further surfaces of the spacer adapted to engage against both sides of a curved corner of a second of the elements, see.

characterised in that the shape and position of each engaging surface is such 15 that when in an engaging position with respect to respective sides of an element each engaging surface of the spacer is aligned with respect to the side so that there will be no wedging shapes accessible to concrete if poured thereon.

In preference the spacer effects an absence of a wedging shape accessible to concrete by having at least said engaging surface of a shape and size curved to match the curved shape of the respective corner of the lost formwork element so that all of the perimeter at least will lie with substantially touching Scontact against the lost formwork element.

In another preferred way the spacer achieves this result by having a cover having an edge that will closely follow and engage with touching contact the curve shape of the lost formwork element thereby excluding access there past of concrete with aggregate.

The invention in one form can also be said to reside in the combination of a spacer having any one of the above characteristics and that in contact with the respective engaging surfaces with respective corners of lost formwork elements such as lost formwork elements made from polystyrene foam and 3 5 having curved corners.

Reference is being made to lost formwork elements. These are often referred to in the building trade as void formers or waffle pods or pods for a waffle pod foundation, which are intended to be consistent with the reference to lost formwork elements.

Some assistance will be gained in understanding the discovery and the implementation of the invention by reference to preferred embodiments which shall be described with the assistance of drawings wherein: FIG 1 is a perspective view of a spacer according to a first embodiment, FIG 2 is a perspective view of a spacer according to a second embodiment.

FIG 2a is a further version of the second embodiment, 1 0 FIG 3 is a perspective view of a part of a spacer which exists but where there is shown an insert adapted to fit over the existing cheeks of engaging faces of .a corner of a spacer, S FIG 4 is a plane view of spacers in an arrangement according to a further embodiment, FIG 5 is a cross sectional view along the lines 5-5 in FIG 6, and FIG 7 is an enlarged view of a portion of FIG Referring initially to FIG 4, there is shown here an arrangement of a plurality of lost formwork elements 1 which are held apart by spacers 2 so that there are left between the elements 1, parallel sided channels 3 in the manner that is *currently used conventionally in building in Australia and elsewhere at the •present time.

2 The elements 1 (which can be referred to as pods or void formers) in this case 2 5 are made from expanded polystyrene foam and have curved corners shown typically at 4 the degree of curvature being selected so that there will be a removal of stress concentration for the concrete footing eventually formed by reason of a sharp or 900 corner.

3 0 The extent of curvature is decided by those otherwise familiar with this industry so as to result in the effective removal of stress concentrations and is well understood by those familiar with this art as compared to a sharp corner for this purpose.

3 5 The problem however that is being addressed is the difficulty that with using conventional spacers, there will result in a space between cheeks or engaging surfaces defining a holding shape for spacers of previous design incorporating a right angular included angle. This leaves, implicitly, wedging shapes which are formed between the curved side of the element 1 and the planar side of the surface.

By having an outermost surface which closely follows the curved shape of the curved corner of each element 1, there quite simply is no such wedging shape within which aggregate of an expected aggregate particle size (typically mms and over) which implicitly includes tapering shapes will get between the two reacting surfaces and cause a resultant outward pressure and therefore displacement of the various elements unnecessarily. Reference to a wedging shape is intended to refer to a shape defined between two surfaces which will in the context then have the result of causing some wedging effect as a result aggregate being located therebetween and with conventional compaction of the pour have this jamming into the wedging shape and forcing the surfaces apart which in relation to any case can be established by a simple testing in 15 practice.

Now referring to FIGS 1 and 2, these refer to two different spacers each having, for each corner, a curved shape so that they will follow closely with substantially touching contact fully around the curved shape of the lost formwork element corner.

Referring then to the first embodiment in detail, this includes a frame structure S* formed from moulded plastics material so that there are a number of 2• interstices between joining parts whereby to allow for ample concrete flow 2 5 either beneath or through into other areas, and there is included four upstanding turrets shown at 10, 11, 12 and 13, each including a respective slot such as at 14 and 15 in turret 10 so as to locate steel reinforcement.

There is however at each corner shown typically at 16, 17, 18 and 19 a shape having an external or outer surface which is adapted to lay flush against the 3 0 curved shape of the corner of a polystyrene foam lost formwork element.

In this case, all of the surface such as shown at 20 is positioned and shaped so that it will lie close or in immediate contact with the corner curved shape of the lost formwork member or otherwise, the framing members and other parts of the spacer are well clear.

This then ensures that there are no interstices or areas in which tapered stones forming a part of aggregate (particularly 10mm and above) will locate between respective faces and with pushing, push them apart.

The second embodiment achieves the same effect in principle but is a somewhat simpler design in so far that there is a central turret 20 with four slots shown generally at 22 and there are frame members shown generally at 23 and 24 which thereby hold corner members shown at 25, 26, 27 and 28.

Again, the shape is chosen so as to match very closely the external curved shape of the respective corner of the polystyrene lost formwork and such that there is no gap then which will exist between the flush external surfaces such as at 29 defining between them the curved shape curved however in only one dimension, but chosen again so as to match exactly that of the external surface of the curved corner. This will ensure that there is no wedging shape accessible to aggregate of poured concrete.

:i Any other elements are kept well separate so that there isn't for instance a planar shape leading into the flush shape of the corner element.

1 5 In FIG 3, the curved shape is achieved by having an insert or cover 30 which simply fits over and by reason of slots 31 interconnects with the top at 32 of the cheek plates 33 and 34.

This has the result then of having the top 35 block any access of aggregate or stones through into an otherwise existing gap and this will achieve much the same result using however an already existing spacer of conventional type.

There are accordingly wedging shapes but they are not accessible to the aggregate of the concrete that will be poured thereover.

*Oi* 25 Finally we show in FIGS 5, 6 and 7 the way in which the shapes do take a face to face or touching alignment so that we have the polystyrene lost formwork element 40 which has against it the curved cheek 41 such that there is no essential space between them, that is, they are in continuous surface to surface contact.

This is more clearly shown perhaps in FIG 6 where there are typically frame members 43 but the corner element at 40, 41 is shown to follow and can conform accurately to the corner shape of the element 3 5 This is shown in enlarged view in FIG 7.

This then concludes the description of the embodiments.

IC I' 8 From this it will be seen that there a number of ways in which the invention can be carried out but in every case.

It is intended that the invention shall either apply to the spacer adapted to be used for lost formwork with curved corners so that the problem can be removed, or the invention can reside in the assembly including the spacers in position with respect to the curved corner elements or it can reside in the method of effecting an erection of formwork which includes using spacers of the type described and characterised as has been stated, and using these in connection and assembly with formwork with curved corners so as to ensure there are no gaps of such a size that aggregate will either fully or partially enter into a gap shape and thereby cause separation forces sufficient to dislodge location of the members.

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Claims (10)

1. A spacer for holding apart by engaging at or close to the corners each of at least two lost formwork elements each of the elements being generally rectilinear in outermost dimensions with at least one curved corner, the spacer including engaging surfaces adapted to engage against both sides of a curved corner of a first of the elements and further surfaces of the spacer adapted to engage against both sides of a curved corner of a second of the elements, characterised in that the shape and position of each engaging 1 0 surface is such that when in an engaging position with respect to respective sides of an element each engaging surface of the spacer is aligned with respect to the side so that there will be no wedging shapes accessible to o concrete if poured thereon. o:'i 15 2. A spacer as in claim 1 further characterised in that the spacer effects absence of a wedging shape accessible to concrete .by having at least said engaging surface of a shape and size curved to match the curved shape of the respective corner of the lost formwork element so that all of the perimeter at least will lie with substantially touching contact against the lost formwork 20 element.

3. A spacer as in claim 1 further characterised in that the spacer effects absence of a wedging shape accessible to concrete by having a cover having an edge that will closely follow and engage with touching contact the curve 25 shape of the lost formwork element thereby excluding access there past of concrete with aggregate.

4. A spacer as in claim 1 further characterised in that the spacer effects absence of a wedging shape accessible to concrete by having a spacer having for each respective corner two engaging surfaces which are aligned to engage respective only planar sides one to each side of a corner of a lost formwork element. A spacer for holding apart by engaging at or close to the corners each of four lost formwork elements each of the elements being generally rectilinear in outermost dimensions with at least one curved corner ,the spacer including engaging surfaces adapted to engage against both sides of a curved corner of a first of the elements and further surfaces of the spacer adapted to engage against both sides of a curved corner of a second of the elements and respectively a third of the elements and a fourth of the elements, characterised in that the shape and position of each engaging surface is such that when in an engaging position with respect to respective sides of an element each engaging surface of the spacer is aligned with respect to the side so that there will be no wedging shapes accessible to concrete if poured thereon.

6. An arrangement with a spacer as characterised in any one of the preceding claims 1-5 which spacer is positioned with respect to at least two of 1 0 lost formwork elements so as to hold these apart by having respective surfaces of the spacer holding the respective corners of the respective :i elements so that there are no wedging shapes accessible to concrete if o poured thereon. 15 7. An arrangement with a spacer as characterised in any one of the preceding claims 1-5 which spacer is positioned with respect to at least two of lost formwork elements so as to hold these apart by having respective surfaces of the spacer holding the respective corners of the respective elements so that there are no wedging shapes accessible to concrete cast 20 thereon.

8. An arrangement as in either one of preceding claims 6 or 7 further S"characterised in that each of the lost formwork elements is comprised of foamed polystyrene. C

9. A footing having therein a spacer as in any one of the preceding claims A suspended floor having therein a spacer as in any one of the preceding claims

11. A ceiling having therein a spacer as in any one of the preceding claims

12. Any one of the following having an arrangement as in any one of claims 6,7 or 8 namely a footing, a suspended floor or a ceiling. 11

13. A spacer substantially as described in the specification with reference to and as illustrated by any one or more of the accompanying drawings.

14. An arrangement substantially as described in the specification with reference to and as illustrated by any one or more of the accompanying drawings. Dated this 6th day of January 1999 NICOLA LEONARDIS By his Patent Attorneys, COLLISON CO. o*o* *oooo *g *oo