AU2004202483B2 - Spacer for concrete reinforcing - Google Patents

Description

AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: SPACER FOR CONCRETE REINFORCING Applicant: Modfix Australia Pty Ltd The following statement is a full description of this invention, including the best method of performing it known to me: 1 2 SPACER FOR CONCRETE REINFORCING BACKGROUND OF THE INVENTION Field of the Invention 5 This invention relates to a spacer for supporting reinforcing material, such as metal bar and mesh, in concrete. The spacer is applicable for use with form work for voided raft slabs such as those for building foundations, and it will be convenient to hereinafter disclose the invention in relation to that exemplary application. However, it is to be appreciated that the invention is not limited to 10 that application. Description of the Prior Art One type of form work used for voided concrete slabs involves an array of spaced apart blocks, boxes or other bulk form voider elements, typically known as "pods", rafted together with metal reinforcing bar and mesh, and around and 15 over which concrete is poured and allowed to set in order to form the concrete slab. In one arrangement, pods are square shaped in plan view and measure about 1090 x 1090 mm. Since they are lost to the slab, they are usually composed of cardboard, plastics such as polystyrene foam, or other inexpensive and light weight materials of adequate strength to support the 20 reinforcing material and concrete until set. The reinforcing material is installed in trenches defined between the spaced apart pods and over the upper surface of the pods. In order to maintain the material in accurate location relative to the pods until the concrete is poured and set, bar chairs or spacers are installed between the reinforcing material and 25 formwork. The bar chairs locate the reinforcing bars or mesh in spaced relation to the upper surface of the pods so that the bars or mesh will extend in the upper half of the concrete covering the pods. In one form, the reinforcing bars or mesh are spaced from the upper surface of the pods by bar chairs placed under the bars or mesh and bearing on 30 the pod upper surfaces. Typically, four bar chairs are arranged in spaced apart relation over each pod in order to adequately support the bars or mesh. Those bar chairs are moulded of plastic material and have a small base for bearing on the pod upper surface, an upright support extending from the base, and a seat on the support spaced from the base for supportingly receiving a bar or mesh.

3 The seat is usually placed under the bar or mesh wire so as to secure the bar or mesh and spacer together in a stable relationship. A problem with these bar and mesh supporting bar chairs is that they tend to compress or crush the quite soft pod material under the working loads and 5 weight of the bar and mesh, and concrete whilst being poured, so that the bar chair settles or sinks into the pod. s a result, the spacing between the pod and bar or mesh is disturbed, with the bar or mesh moving into the lower half of the concrete covering the pods. As a consequence, the reinforcing provided by the bar and mesh becomes much less effective. 10 Some pods have internal ribbing which provides localised strengthening to the pod walls providing the upper surfaces. Provided the bar chairs are positioned in those strengthened regions, then the extent of bar chair movement can be minimised. However, it is not always convenient to position the bar chairs in those regions, particularly with different mesh configurations and dimensions, In those 15 circumstances, the working loads and weight of the supported bar and mesh and poured concrete will potentially cause the bar chairs to pierce through the upper surface of the pods. The bar chair movement is aggravated by construction workers standing on and walking over the bar and mesh, such as during mesh installation and finishing 20 off the formwork prior to a concrete pour, In an effort to minimise that effect, a procedure has been developed for installing the reinforcing bar and mesh involving laying all of the bar and mesh over the array of pods and then fitting the bar chairs under the mesh, or "chairing up" so as to space the bar and mesh from the pods. However, this procedure is time consuming and heavy work if all of the bar chairs 25 are to be correctly positioned. SUMMARY OF THE INVENTION It is an object of the present invention to provide a simple spacer for properly supporting reinforcing material on concrete formwork without the need for special 30 construction procedures. According to the present invention, there is provided a spacer for supporting concrete reinforcing mesh on pod formwork, including: an elongate base having a 4 bearing surface for bearing on the formwork, the bearing surface being a single, planar and continuous surface extending substantially an entire length of the spacer; an elongate support having a support surface fixed in spaced parallel relationship to the bearing surface for supporting the reinforcing mesh in spaced 5 relation to the formwork, the support surface being a single, planar and continuous surface extending substantially the entire length of the spacer adapted to abut successive parallel bars of said reinforcing mesh at spaced locations along its length and to thereby support each of said parallel bars at the same height above the bearing surface; and web means extending between the base and the support 10 for maintaining the base and the support in spaced apart relationship, the web means having at least one aperture for allowing flow of concrete through the spacer; wherein the base includes a longitudinally extending spine portion having opposed longitudinal side edges, and at least one rib portion projecting laterally from one of said edges of the spine portion, the spine portion and the at least one 15 rib portion together providing the bearing surface thereby providing a configuration enabling stable support of the reinforcing mesh on the formwork. Preferably, a plurality of rib portions are provided, the rib portions projecting from both side edges of the spine portion. Preferably, a respective series of rib portions are spaced apart along each 20 side edge. More preferably, the rib portions of one series are offset from the rib portions of the other series along the spine portion. In a preferred example, the rib portions project perpendicularly to the longitudinal extent of the spine portion. Preferably, the base is a base plate, and the spine portion is elongate 25 rectangular in plan view. More preferably, each of the rib portions is square or rectangular in plan view. Preferably, the support is a support plate, the support plate being elongate rectangular in plan view. In a preferred example, the rib means includes at least one spacing web 30 extending between the base and support in a direction along the base and support. More preferably, the or each spacing web extends between the base and support at least substantially perpendicular thereto. In one form, a single spacing 4a rib is provided, the spacing web being an elongate web plate with opposite longitudinal side edges respectively connected to the base and support. In a preferred example, the rib plate extends at least substantially wherein the web plate extends at least substantially continuously along the base and support. 5 Preferably, the spacer is of generally I-transverse cross sectional shape. Preferably, the web means includes one or more reinforcing webs for stiffening the or each rib portion, respectively, against deflection relative to the spine portion. More preferably, the or each reinforcing web extends from a respective rib portion and is connected to the spacing web. Even more preferably, 10 the or each reinforcing web extends to and is connected to the base and support. Preferably, the or each reinforcing web is a web flange extending perpendicular to the web plate.

5 DESCRIPTION OF THE DRAWINGS The following description refers to a preferred embodiment of the spacer of the present invention. To facilitate an understanding of the invention, reference is made in the description to the accompanying drawings where the 5 spacer is illustrated in that preferred embodiment. It is to be understood that the spacer is not limited to the preferred embodiment as hereinafter described and as illustrated in the drawings. In the drawings: Fig. 1 is a perspective view of a spacer according to a preferred 10 embodiment of the present invention in use supporting concrete reinforcing material on formwork; Fig. 2 is a different perspective view of the spacer of Fig. 1; Fig. 3 is a top view of the spacer of Fig. 1; Fig. 4 is a side view of the spacer Fig. 1; 15 Fig. 5 is a bottom view of the spacer of Fig. 1; and Fig. 6 is an end view of the spacer of Fig. 1. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 20 Referring initially to Fig. 1 of the drawings, there is generally shown a spacer 1 for supporting concrete reinforcing bar or mesh R in spaced apart relation to formwork F. Formwork F is typically one of an array of voider elements or pods rafted together, and over which concrete is poured to form voided concrete slab. The spacer 1 bears on upper surface S of the formwork .25 F, and the reinforcing bar or mesh R in turn bears on the spacer 1. The spacer 1 is shown in more detail in the remaining drawing Figs, and includes an elongate base 2 having a bearing surface 3 for bearing on the formwork F, and an elongate support 4 spaced from the base 2 for supporting the bar or mesh R in spaced relation to the formwork F. The spacer 1 also 30 includes web means 5 for maintaining the spaced apart relationship between the base 2 and support 4. The base 2 and support 4 extend parallel to one another, and the web means 5 extends between the base 2 and support 4 to maintain them in spaced apart relation.

6 The base 2 has a longitudinally extending spine portion 6, and a plurality of rib portions 7 projecting outwardly therefrom, the portions 6, 7, together providing the bearing surface 3. The rib portions 7 provide the spacer 1 with additional stability against toppling, in use. 5 As shown, the spine portion 6 has opposite longitudinal side edges 8 and the rib portions 7 projects laterally from each of the edges 8. In particular, a respective series of rib portions 7 are spaced apart along each side edge 8. In the preferred arrangement, the rib portions 7 of one series are longitudinally offset from the rib portions 7 of the other series, in order to increase the spread 10 of the bearing surface 3 and so improve stability in the spacer 1. The rib portions 7 project perpendicularly to the longitudinal extent of the spine portion 6. In this embodiment, the base 2 is in the form of a plate. The spine portion 6 is elongate rectangular, and each of the rib portions 7 is square or rectangular 15 in plan view. It will be appreciated that the rib portions 7, in particular, may be of other suitable shapes. The bearing surface 3 is planar throughout its extent. However, it should be appreciated that the bearing surface 3 may have some interruptions in order to facilitate location on the supporting formwork F. In the exemplary application 20 for the spacer 1, the bearing surface 3 may be provided with one or more spikes or other projections (not shown) extending from the bearing surface 3 for engaging in the pod formwork upper surface S, in order to fix the location of the spacer 1 on the upper surface S. The support 4 has a supporting surface 9 on which the reinforcing bar or 25 mesh R bears for spatial support. That surface 9 extends parallel to the bearing surface 3 of the base 2. In this embodiment, the support 4 is in the form of a plate. The support plate 4 extends parallel to the base plate 2. The support plate 4 is elongate rectangular in plan view, with opposite longitudinal side edges 10. 30 The supporting surface 9 is planar throughout its extent. However, it should be appreciated that the supporting surface 9 may have interruptions thereon in order to facilitate support of the reinforcing R thereon. In the exemplary application for the spacer 1, the supporting surface 9 may be provided with one or more clips (not shown) into which reinforcing bar can be 35 received in order to positively secure the bar relative to the spacer 1.

7 The web means 5 includes a spacing web 11 extending between the base 2 and support 4. The spacing web 11 extends in a direction along the base 2 and support 4. That is continuous along the length of the base 2 and support 4 in this embodiment, but in alternative embodiments may be intermittent or 5 discontinuous. The spacing web 11 extends perpendicular between the parallel base 2 and support 4. In this embodiment, spacing the web 11 is in the form of a plate. The web plate 11 is elongate with opposite longitudinal side edges 12 respectively 10 connected to the base and support plates 2, 4. The web plate 11 is connected along the base and support plates 2, 4 centrally between their longitudinal side edges 8, 10. The web plate 11 extends in a plane perpendicular to the planes of the-base and support plates 2, 4. Thus, in this embodiment, the spacer 1 has a generally I transverse cross-sectional shape. 15 The web plate 11 extends continuously along the base and support plates 2, 4. However, holes 13 are provided in the web plate 11 so as to allow concrete to flow therethrough. The holes 13 may be circular (as shown), or other convenient shape, and equally spaced apart along the web plate 11. The holes 13 are located closer to the base plate 2 than the support plate 4, and are 20 spaced so that two holes 13 are positioned between each adjacent pair of rib portions 7 of the base plate 2. The web means 5 also includes reinforcing webs 14 to strengthen and stiffen the rib portions 7 against deflection relative to the spine portion 6 a plurality of reinforcing webs 14 are provided, one each associated with a 25 respective rib portion 7. Those reinforcing webs 14 extend from the rib portions 7 to the spine portion 6, spacing web 11, and support plate 4. In this embodiment, the reinforcing webs 14 are in the form of flanges. The web flanges 14 extend perpendicularly to the web plate 11, and to the base and support plates 2, 4. The web flanges 14, are positioned centrally of their 30 respective rib portions 7. In this embodiment, the spacer 1 is formed in one piece. That may be achieved by moulding the spacer 1 from plastics material. In the exemplary application, the spacer 1 is about 600 mm long. Thus, the bearing and supporting surfaces 3, 9 are of that length. The spacer 1 has a 35 dimension (height) between the bearing and supporting surfaces 3, 9 of up to 8 about 100 mm depending on the desired spacing of the supporting reinforcing R from the formwork F. In the exemplary application, the spacer 1 will desirably support a weight of about 155 kilograms on a polystyrene foam pod without causing the upper 5 surface S of the pod to compress or crush more than about 5 mm. That can be achieved with a bearing surface 3 of about 180 square centimetres, provided in one example by a spine portion 6 measuring approximately 600 x 20 mm, and rib portions 7 each measuring approximately 20 x 30 mm and spaced apart approximately 65 mm along each side edge 8 of the spine portion 7. 10 In use of a preferred spacer 1 in the exemplary application, it is sufficient to provide two spacers 1 on each pod upper surface S. On pods measuring approximately 1090 x 1090 mm, the spacers 1 can be positioned parallel to and spaced about 250 mm from two opposite sides of the pod, with the ends of the spacers 1 being equidistant also about 250 mm from the adjacent other sides of 15 the pod. In this position, reinforcing bars or mesh R overlying the pod array will bear on the supporting surfaces 9 so that the spacers 1 properly support and maintain reinforcing bars or mesh R the prescribed distance from the upper surfaces S. The extended bearing surface 3 enables the spacer 1 to stably support the 20 reinforcing R without settling into or piercing the upper surface S of soft material pods during normal building constructions. This improved support can be achieved without the need for construction workers to exercise any greater care in positioning the spacers 1 or carrying out the method of construction. In particular, the spacers 1 will achieve proper support even if they are not all 25 precisely located over strengthening regions of the pod upper wall. Moreover, the spacers 1 can permit progressive "chairing up" of the reinforcing R as it is laid over the pod array and so save on installation, time and cost. The spacer 1 has improved stability against tipping or toppling, so as to better support the reinforcing R against inadvertent movement, particularly during a concrete pour. 30 Finally, it is to be understood that various alterations, modifications and/or additions may be made to the spacer without departing from the ambit of the present invention as defined in the claims appended hereto.

9 The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the 5 common general knowledge in the field of endeavour to which this specification relates. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated 10 integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (18)

1. A spacer for supporting concrete reinforcing mesh on pod formwork, including: 5 an elongate base having a bearing surface for bearing on the formwork, the bearing surface being a single, planar and continuous surface extending substantially an entire length of the spacer; an elongate support having a support surface fixed in spaced parallel relationship to the bearing surface for supporting the reinforcing mesh in spaced 10 relation to the formwork, the support surface being a single, planar and continuous surface extending substantially the entire length of the spacer adapted to abut successive parallel bars of said reinforcing mesh at spaced locations along its length and to thereby support each of said parallel bars at the same height above the bearing surface; and 15 web means extending between the base and the support for maintaining the base and the support in spaced apart relationship, the web means having at least one aperture for allowing flow of concrete through the spacer; wherein the base includes a longitudinally extending spine portion having opposed longitudinal side edges, and at least one rib portion projecting laterally 20 from one of said edges of the spine portion, the spine portion and the at least one rib portion together providing the bearing surface thereby providing a configuration enabling stable support of the reinforcing mesh on the formwork.

2. A spacer as claimed in claim 1, wherein a plurality of rib portions are 25 provided, the rib portions projecting from both side edges of the spine portion.

3. A spacer as claimed in claim 1 or 2, wherein a respective series of rib portions are spaced apart along each side edge. 30

4. A spacer as claimed in claim 3, wherein the rib portions of one series are offset from the rib portions of the other series along the spine portion. 11

5. A spacer as claimed in any one of claims 1 to 4, wherein the rib portions project perpendicularly to the longitudinal extent of the spine portion.

6. A spacer as claimed in any one of claims 1 to 5, wherein the base is a base 5 plate, and the spine portion is elongate rectangular in plan view.

7. A spacer as claimed in claim 6, wherein each of the rib portions is square or rectangular in plan view. 10

8. A spacer as claimed in any preceding claim, wherein the support is a support plate, the support plate being elongate rectangular in plan view.

9. A spacer as claimed in any preceding claim, wherein the web means includes at least one spacing web extending between the base and support in a 15 direction along the base and support.

10. A spacer as claimed in claim 9, wherein the or each spacing web extends between the base and support at least substantially perpendicular thereto. 20

11. A spacer as claimed in claim 9 or 10, wherein a single spacing web is provided, the spacing web being an elongate web plate with opposite longitudinal side edges respectively connected to the base and support.

12. A spacer as claimed in claim 11, wherein the web plate extends at least 25 substantially continuously along the base and support.

13. A spacer as claimed in any preceding claim, wherein the spacer is of generally 1-transverse cross sectional shape. 30

14. A spacer as claimed in any preceding claim, wherein the web means includes one or more reinforcing webs for stiffening the or each rib portion, respectively, against deflection relative to the spine portion. 12

15, A spacer as claimed in claim 14, when appended to any one of claims 9 to 12, wherein the or each reinforcing web extends from a respective rib portion and is connected to the spacing web. 5

16. A spacer as claimed in claim 15, wherein the or each reinforcing web extends to and is connected to the base and support.

17. A spacer as claimed in any of one claims 14 to 16 when appended to claim 10 11 or 12, wherein the or each reinforcing web is a web flange extending perpendicular to the web plate,

18. A spacer for supporting concrete reinforcing on pod formwork, substantially as hereinbefore described with reference to what is shown in the accompanying 15 drawings,