WO2008052243A1

WO2008052243A1 - Void former

Info

Publication number: WO2008052243A1
Application number: PCT/AU2007/001458
Authority: WO
Inventors: Ernest Comerford; Mark Rankin
Original assignee: Sugar Steel Engineering Pty Ltd
Priority date: 2006-11-02
Filing date: 2007-10-02
Publication date: 2008-05-08

Abstract

A void former (10, 310) for forming a void in settable material (such as concrete) includes a body (11, 311) and a cavity (18, 318) disposed in the body. The cavity is shaped to receive one or more reinforcing members (50) and in one form includes a retaining arrangement (22, 332) that retains an end (51) of the reinforcing (50) in the cavity. A formwork assembly and a method of construction is also disclosed.

Description

VOID FORMER

Technical Field

The present invention relates to void formers for forming a void in a settable material. The invention has particular application to forming voids in cementitious material to access steel reinforcing and is herein described in that context. However, it is to be appreciated that the invention has broader application.

Background hi the construction industry, structures (such as walls, floors, slabs, columns and the like) of concrete are produced by positioning reinforcing such as steel reinforcing bars in a region where concrete is then poured to produce the structure. It is useful for the construction process for some of the vertical walls of the structure to be completed prior to the floors, additional walls and other elements of the building. This allows the building to progress more quickly than it would if complete floors of the building were built one at a time.

Because the vertical walls precede other elements of the structure, it is necessary to supply some method of connecting the already completed vertical walls with the other following elements of the structure. The reinforcing bars must be supported in desired positions and often there is need to join length of bars together to ensure that the reinforcing not only is correctly positioned, but is able to transmit load across the wall or floor structures.

The connection of already completed vertical walls with other following elements is typically done using a variety of methods including pre-positioning inserts which allow threaded bars to be screwed into the insert at a later stage or placing bars bent into a shape which can fit inside the dimensions of the walls. These bent bars are later re-bent so as to protrude into the new element to be connected to the wall.

There are serious problems associated with both these types of connectors. For the pre- positioned threaded insert, the thread is often a coarse thread rolled into the reinforcing bar which needs to have a generous tolerance with the insert into which the bar is screwed. This allows the threaded bar to be screwed into the insert without the use of special tools. The generous tolerance between the rolled thread bar and the insert means that the slip in the joint can be too great to prevent lateral movement on a particular bar over a number of cycles of compression and tension. This can result in excessive concrete cracking.

The pull out bar system requires bars to be straightened onsite. This is performed using a straight pipe which causes the restraightened bar to have an S-shape at the restraightened length. This restraightened length has a small re-bending radius and is limited in its ability to resist tensile load.

Summary of the Invention

In a first aspect, the present invention provides a void former for forming a void in settable material, the void former comprising a body, and a cavity disposed in the body, the cavity being shaped to receive one or more reinforcing members.

Accordingly, a void former is provided which incorporates a cavity shaped to receive one or more reinforcing members. In this way, the void former can be utilised to locate the reinforcing prior to introduction of the settable material and also provides a means by which access to that reinforcing can be provided by removal of the void former on curing of the settable material. Typically this access is used to couple the reinforcing member to additional reinforcing to thereby provide continuity in the reinforcing in the resulting structure.

This invention has particular application in the construction industry to form the connection between steel reinforced concrete elements such as walls, floors, slabs, columns and the like.

In a particular form, the cavity is adapted to receive an end portion of the reinforcing member. In one form, the body has opposite first and second ends and the cavity is open to the first end of the body.

In a particular arrangement, the cavity includes a bottom portion that closes the cavity to the second end of the void former.

In a particular form the body of the void former tapers from the second end to facilitate removal of the void former from the hardened settable material.

In a particular form, the body has an outer surface that extends between the first and second ends and an inner surface that defines at least part of the cavity. Preferably, these wall surfaces are spaced apart so that the body portion is relatively thick. Spacing of these surfaces increases the volume of the void which will extend about the reinforcing member thereby providing easier access to the one or more reinforcing members which are exposed on removal of the void former.

In a particular form, the void former further comprises a base which is disposed at the second end of the body and that base is adapted to be fixed to a structure such as formwork or the like. In use, one or more void formers can be fixed to formwork. The formwork is used to provide a cavity in which the settable material is applied. Prior to introducing the settable material the reinforcing is installed within the cavity with part of that reinforcing being disposed within the void former. In one form, the void former supports the reinforcing member. With this arrangement, the or each void former can be used to correctly position its associated reinforcing member and also support that reinforcing member whilst it is disposed within the cavity formed by the formwork. Once the settable material is introduced into the cavity and has cured or hardened sufficiently, the formwork can then be stripped and stripping the formwork also causes the or each void former to be removed from the hardened structure. The resulting void formed by removal of each void former is arranged to extend around the reinforcing member associated with that void former thereby exposing that reinforcing member.

In a particular form, the void former further comprises a retaining arrangement positionable within the cavity, the retaining arrangement being adapted to retain the reinforcing in position within the cavity. - A -

In one form, this retaining arrangement forms a recess within the cavity which is operative to receive a terminal end of the inserted reinforcing.

In a particular form where the void former includes a bottom portion that closes the well to the second end, the bottom portion may be profiled to form the retaining arrangement. In one form that bottom portion is profiled in a stepped configuration to form a recess that receives a terminal end of the reinforcing.

In another form, the retaining arrangement is in the form of an insert that is locatable within the cavity.

In one form the insert is arranged to retain the reinforcing in the cavity by an interference fit. In a particular arrangement the insert is profiled and arranged to interfit with a profiled surface of the reinforcing member.

In one form, the cavity is generally cylindrical and the reinforcing member and insert, when in interfitting engagement, have an exterior surface that generally conforms to the cylindrical cavity.

Embodiments of the void former are ideally suited to be used with reinforcing which incorporates the facility to enable easy coupling of one end of a reinforcing element to an end of another section of reinforcing. Such a coupling arrangement is disclosed in the Applicant's earlier international application PCT/AU2006/00163 the contents of which are herein incorporated by cross reference. In that application, the reinforcing incorporates an end portion having an engagement face which is stepped and which incorporates locking formations arranged thereon to interfit with a complementary shaped end portion of another reinforcing element to form an interlock operative to accommodate axial loading. A retaining sleeve may be disposed over the interlock to thereby maintain the two reinforcing elements in the interlocked condition.

In a further aspect, the invention is directed to formwork that incorporates an inner surface on which at least one void former is disposed. In yet a further aspect, the invention is directed to an assembly comprising a void former which incorporates a retaining arrangement and a reinforcing member.

In yet a further aspect, the invention is directed to an assembly comprising a void former incorporating a retaining arrangement in any form described above and a reinforcing member arranged to be disposed in the void former. The reinforcing member has an end portion that cooperates with the retaining arrangement so that the reinforcing member is retained in the cavity of the void former.

In yet a further aspect, a method of construction is disclosed which comprises positioning a void former in an area of construction, disposing a reinforcing member in the area of construction with a portion of that member extending into the void former, pouring a settable material in the area of construction, providing conditions to allow the settable material to harden, and removing the void former from the hardened material so as to expose the portion of the reinforcing member.

In one form, the void former is affixed to formwork which defines a surface of the area of construction. In one form, the reinforcing member is supported in the area of construction prior to pouring of the settable material by engagement of the reinforcing member with the void former.

Brief Description of the Drawings

It is convenient to hereinafter describe embodiments of the present invention with reference to the accompanying drawings. It is to be appreciated, however, that the particularity of the drawings and their related description is to be understood as not limiting the preceding broad description of the invention.

In the drawings:

Fig. 1 is a perspective view of the void former of one embodiment of the present invention; Fig. 2 is a perspective cross-sectional view of the void former of Fig 1;

Fig. 3 is a bottom perspective view Fig 1 ;

Fig. 4 is a detailed cross-sectional elevation of a formwork assembly incorporating the void former of Fig 1; Fig. 5 is a perspective view of the void former (without insert) of a second embodiment of the present invention;

Fig. 6 is a top view of the void former of Fig. 5;

Fig. 7 is a bottom perspective view of a void former of Fig. 5;

Fig. 8 is a an exploded view illustrating the void former of Fig. 5 with insert and a reinforcing member arranged to be received within the void former;

Fig. 9 is a cross section elevation illustrating the connection of the reinforcing member with the void former of Fig. 5;

Fig. 10 is a detailed perspective view of the insert of the void former of Fig. 5;

Fig. 11 is a bottom perspective view of the insert of Fig. 10; Fig. 12 is a bottom view of the insert of Fig. 10;

Fig. 13 is a cross section elevation of a partially constructed connection between a wall and slab of a reinforced concrete structure; and

Fig. 14 is the cross-section elevation of the completed connection of Fig. 13.

Detailed Description of a Preferred Embodiment

Referring to the Figs 1 to 3, a void former 10 for forming a void in a settable material is shown. The void former 10 has particular application for use with cementitious material such as concrete for use in building construction as will be discussed in more detail below.

The void former 10 incorporates a body 11 which extends between first and second ends (12 & 13). The body has an outer surface 14 which tapers from the second end 13 towards the first end 12. A base 15 is disposed at the second end 13 and in the illustrated form comprises an annular flange which projects from the outer surface 14 of the body. The flange also incorporates tabs 16 which include apertures 30 to receive mechanical fasteners such as screws or the like. As best illustrated in Fig 2, the void former 10 further incorporates a cavity in the form of a holding well 18 which extends into the void former body 11 from the first end 12. The holding well 18 is defined by an inner wall 19 of the body 11 and incorporates an opening 20 at the first end 12 but is closed to the second end 13 by bottom portion 21. The bottom portion 21 is profiled to include a stepped configuration so as to form a recess 22 at the bottom of the holding well 18. The purpose of the recess 22 will be discussed in more detail below with reference to Fig. 4.

The body 11 of the void former 10 is constructed so as to be relatively thick. The outer surface 14 of the body is spaced from the inner surface 19 which defines the holding well 18. To create this thickness whilst making efficient use of material, the body portion 11 incorporates two walls (23 & 24 as best illustrated in Fig. 3), interconnected by webs 25. These webs are spaced apart and cavities 26 are disposed between these webs and are defined by the respective annular walls 23 & 24 and adjacent webs 25. With this arrangement, the outer surface 14 is formed as the outer surface of the wall 23 whereas the inner surface 19 is formed as an inner wall surface of the wall 24.

Typically the void former 10 is formed from a polymeric material typically through an injection moulding process. However, it is to be appreciated that the void former could be formed from any other suitable material as will be appreciated by those skilled in the art.

The void former 10 in the illustrated form is arranged to be used in the construction industry and is affixed to the inside face of formwork 100 (see Fig. 4). In general terms, the void former is able to be used to allow the interconnection of steel reinforcing across two separately cast structures. Such an arrangement is disclosed in Fig. 14, which illustrates the connection between a reinforced concrete wall 500 and a reinforced concrete slab 600. hi this arrangement, the wall 500 is formed prior to formation of the slab 600.

To cast the wall structure 500, formwork is erected to define a cavity 101 as shown in Fig. 4. The formwork includes the formwork section 100 which typically incorporates a plurality of the void formers 10 (only one of which is shown) on an inner surface 102 thereof. With this arrangement, the void formers 10 extend into the cavity 101 so as to provide the void 503 in the surface 504 of resulting wall 500 after casting of the concrete matrix 502.

The reinforced concrete wall 500 incorporates steel reinforcement (generally designated 501) embedded in a concrete matrix 502. The reinforcing 501 includes "starter" bars 50 that are L shaped and which are embedded in the wall matrix 502 but which are also arranged to be connected to reinforcing 601 in the slab 600. These bars have an end portion 51 that are disposed in respective voids 503 that are formed on the surface 504 of the wall 500 by a plurality of the void formers 10. These end portions 51 are coupled to end portions 602 of the tensile reinforcing bars 603 and the voids 503 are subsequently filled on casting of the slab concrete matrix 604.

Prior to introduction of the concrete, the reinforcing 501 is disposed within the cavity 101. This reinforcing includes the reinforcing bars 50 with end portions 51 of those bars being inserted within the holding well 18 of the void formers. In the illustrated form, the end portions 51 are profiled with an interlocking formation incorporating a series of upstands 52. Reinforcing of this type is the subject of the Applicant's international application (PCT/AU2006/00163) entitled "A Reinforcing Bar", the contents of which are herein incorporated by cross reference. With this configuration of reinforcing bar 50, the end portion 51 is generally stepped so that a terminal end 53 is smaller in cross section than the shaft 54 of the reinforcing bar 50 and is specifically designed to locate within the retaining element cavity 22 formed within the base of the holding well 18 of the void former 10. With this arrangement, the void former 10 is designed to properly locate the reinforcing bar 50 in both its correct position and orientation with the cavity 101.

Once the reinforcing 501 is disposed in its correct position within the cavity 101, the cementitious material, or other settable material is then introduced into the cavity and is allowed to cure so as to harden. Once the cementitious material is hardened, the formwork 100 and connected void formers 10, 310 are stripped leaving the voids 503 in the surface of the wall 500 in which the end portions 51 of respective reinforcing are disposed. The formwork 100 incorporating the void formers may then be reused as required.

Turning to Fig. 13, in forming the reinforced concrete slab 600, the formwork 200 is erected to define cavity 201 and the reinforcing 601 is installed which includes connecting the end portions 602 of the tensile reinforcing 603 to the exposed end portion 51 of reinforcing 50. A sleeve 63 is disposed over the inter-engaging end portions to complete the coupling. Once the reinforcing is correctly placed the slab 600 can be cast by introducing concrete into the cavity 201. Once the concrete is cured, the formwork can be stripped leaving the resulting structure as shown in Fig. 14.

Whilst the embodiment shown in Fig 4 uses a void former which is specifically shaped to receive the reinforcing 50 with the stepped end 51, it is to be appreciated that the shape of the holding well could be modified to receive other types of reinforcing bar and also to hold those other types of bars in correct position and orientation. Therefore it is to be appreciated that the invention is not limited to arrangements where the void former 10 is used solely with the profiled reinforcing 50 as shown Fig. 4.

A second embodiment of a void former is illustrated with reference to Figs. 5 to 12. The void former 300 of this second embodiment include many of the features of the void former 10 and like features have been give like reference numerals with the exception that the reference numerals have been prefixed with the numeral 3 to distinguish between the embodiments.

As in the earlier embodiment the void former 310 includes a body 311 that extends between first and second ends 312 and 313. The outer surface 314 of the body 311 is tapered and extends from the second end 313 to the first end 312. A base 315 which is of thicker design as compared to the base 15 in the earlier embodiment is disposed at the second end 313 and includes apertures 330 to receive mechanical fasteners such as screws of the like.

hi a similar arrangement to the earlier embodiment, the void former 310 includes a cavity 318 which extends into the void former body 311 from the first end 312. This cavity or holding well 318 is defined by an inner wall 319 and incorporates an opening 320 at the first end but is closed at the second end by a bottom portion 321. As distinct from the earlier embodiment where the bottom portion was profiled to include a recess 22, the bottom portion 321 of the void former 310 is flat as best illustrated in the sectional view of Fig. 9.

To provide adequate strength to the void former 310 whilst minimizing the materials used in the body 311, the void former 310 includes a plurality of internal ribs 325 which extend between the inner and outer walls 323 and 324 of the void former 310. As will be appreciated by those skilled in the art, the configuration of the ribbing 325 may vary depending on the material used and the strength required of the void former 310.

As in the earlier embodiment, the void former 310 is arranged to receive the end portion

51 of reinforcing bars 50.

To retain those reinforcing bars in position, the void former 310 further incorporates a removable insert 332 which is best illustrated in Figs. 10 to 12. The insert 332 which is made from a relatively hard foam or plastic material is designed to incorporate an engagement surface 331 which incorporates a profiling which interfits with the upstands

52 of the reinforcing bar 50. In this arrangement, when the insert 332 is mounted on the upstands 52 of the end portion 51 of the reinforcing bar, those components 332, 51 have an exterior profile which generally conforms to the inner profile of the cavity 318 of the void former 310 (which in the illustrated example is generally cylindrical). The exterior of the interfitting insert and end portion is arranged to be slightly larger than the cavity 318 so that the reinforcing bar 50 locates in an interference fit in the cavity 318 so that it is snugly retained within the void former 310.

As best illustrated in Figs. 11 and 12, the profile on the engagement surface 333 of the insert 332 includes a series of laterally aligned projections 334 and a series of grooves 335 which are disposed between the aligned projections 334. The purpose of these grooves 335 is to remove unnecessary material from the insert 332 and facilitate moulding of the insert.

While the void formers 10, 310 have been described with relation to a single reinforcing member being inserted therein, the void former could include a holding well and retaining member designed to hold any number of reinforcing members with connectors such as threaded inserts, stepped connectors or other connectors. Further, while a particular design of the reinforcing members has been described, the void former can incorporate a retaining arrangement which is designed for accurate positioning and alignment of a reinforcing member with any shaped end portion or no specific shaped end portion.

Void formers as described above have substantial practical benefit. They allow for the accurate alignment of reinforcing members, particularly reinforcing members with inter-engaging end portions. Further the void formers 10, 310 can be permanently connected with formwork, allowing for the simple positioning of the void formers and the subsequent consistent positioning of the reinforcing members.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Variations and modifications may be made to the void former previously described without departing from the spirit or ambit of the invention.

Claims

1. A void former for forming a void in settable material, the void former comprising: a body, and a cavity disposed in the body, the cavity being shaped to receive one or more reinforcing members.

2. A void former as defined in claim 1, wherein the cavity is adapted to receive an end portion of the or each reinforcing member.

3. A void former according to either claim 1 or 2, wherein the body has opposite first and second ends and the cavity is open to the first end of the body.

4. A void former according to claim 3, wherein the cavity includes a bottom portion that closes said cavity to said second end.

5. A void former according to either claim 3 or 4, wherein the body tapers away from the second end towards the first end.

6. A void former according to any one of claims 3 to 5, wherein the body has an outer surface that extends between said first and second ends and an inner surface that defines at least part of the cavity.

7. A void former according to claim 6, wherein the body is relatively thick between the inner and outer surfaces so as to space those surfaces apart.

8. A void former according to any one of claims 3 to 7, further comprising a base disposed at the second end of the body, the base being adapted to be affixed to formwork.

9. A void former according to any preceding claim, further comprising a retaining arrangement adapted to retain the reinforcing member in position within the cavity.

10. A void former according to claim 9, wherein the retaining arrangement is integrally formed with, or fixed to, the body.

11. A void former according to claim 10, wherein the retaining arrangement forms a recess within said cavity which is operative to receive a terminal end of an inserted reinforcing member.

12. A void former according to claim 11, wherein the cavity includes a bottom portion surface that is profiled to form said retaining arrangement recess.

13. A void former according to claim 12, wherein the bottom portion surface is profiled in a stepped configuration to form said recess.

14. A void former according to claim 9, wherein the retaining arrangement is in the form of an insert locatable in the cavity.

15. A void former according to claim 14, wherein the insert is arranged to retain the reinforcing member in the cavity by an interference fit.

16. A void former according to claim 14 or 15, wherein the insert is profiled and arranged to interfit with a profiled surface of the reinforcing member.

17. A void former according to claim 16, wherein the cavity is generally cylindrical and the reinforcing member and insert, when in interfitting engagement, have an exterior surface that generally conforms to said cylindrical cavity.

18. An assembly comprising a void former according to any one of claims 9 to 17, and a reinforcing member arranged to be disposed in said void former, the reinforcing member having an end portion that cooperates with the retaining arrangement so that the reinforcing member is retained in the cavity of said void former.

19. A formwork assembly comprising formwork having an inner surface and at least one void former according to any one of claims 1 to 17 disposed on said inner surface.

20. A method of construction comprising: positioning a void former in an area of construction; disposing a reinforcing member in the area of construction with a portion of said member extending into said void former; pouring a settable material in the area of construction, providing conditions to allow the settable material to harden; and removing the void former so as to expose said portion of said reinforcing member.

21. A method according to claim 20, wherein the void former is affixed to formwork which defines a surface of the area of construction.

22. A method according to claim 20 or 21 , wherein an end portion of said reinforcing member is inserted in said void former.

23. A method according to any one of claims 20 to 23, wherein said reinforcing member is supported in the area of construction prior to pouring of said settable material, by engagement of the reinforcing member with said void former.

24. A method according to any one of claims 20 to 23, wherein the void former is in accordance with any one of claims 1 to 17.