AU2008255272B2 - Improvements in and in relation to concrete form work - Google Patents

Abstract

A joint 10 between two adjacent concrete slabs 11 and 12 is formed by first pouring a slab 12 using the joint form 13. The joint form 13 is lost form work and employs a joint plate 14 and an anchor plate 15 secured by rivets 16 to the joint plate 14. Dowel sleeves 17 are located at intervals along the joint plate. The dowel sleeves 17 take a square dowel plate 18 with the joint plate intersecting a diagonal of the dowel plate corner to corner. Stakes 19 pass through holes 20 in U-shaped stake plates 22 fastened to the joint plate with rivets. The joint plate has a bottom flange 23 and a top flange 24 with a return flange 25. The anchor plate has a top flange 26 and a return flange 27. The flanges 23 and 26 are aligned and appear exposed in the finished slab. The has a web 28 and an anchor flange 29 formed with an undulating edge 30. The edge 30 is formed by providing cut-outs in the flange which facilitate displacement of the edge by bending at every second tab between the cutouts to displace the edge by about 100 to the flange fold line 33 to form the undulating edge 30.

Description

1 P/00/011 Regulation 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: DANLEY CONSTRUCTION PRODUCTS PTY LTD Actual Inventor(s): ASH, Alistair; ROGERS, Ryan and IRELAND, Bruce Address for Service: INTELLEPRO Patent & Trade Mark Attorneys Level 7 102 Adelaide Street BRISBANE, QLD, 4000 (GPO Box 1339, BRISBANE, 4001) Invention Title: IMPROVEMENTS IN AND IN RELATION TO CONCRETE FORM WORK Details of Associated Australian Patent Application No 2007906778 Provisional Application(s) No(s): filed 13 December 2007. The following statement is a full description of this invention, including the best method of performing it known to me: 2 IMPROVEMENTS IN AND IN RELATION TO CONCRETE FORM WORK Embodiments of this invention relate to concrete constructions, to form work used in concrete joint forming in concrete slabs and in particular but not limited to reduction in form induced cracking or failure arising from use of lost form work. Concrete laid in large areas is prone to movement that may result in irregularities including, amongst others, cracking and slab surface misalignment. It is usual to "control" concrete using various arrangements of joints including contraction and expansion joints. It is also usual to pour large areas in sections separated by dowelled joints using metal forms. Typical joints employ a lost metal form with dowels used to keep the adjacent slabs in alignment. The metal form may be "anchored" by being "keyed", as in a "key joint", having a portion of the metal form displaced laterally or the metal form may include projections for aiding retention of the form in the concrete. It is also usual to control cracking by creating artificial lines of weakness. The presence of any foreign object including the metal form, anchoring elements, dowels and so on disrupt and interfere with the continuity in the slab and coupled with contraction, expansion and loading unpredicted lines of weakness may appear. Thus any improvement that would limit the interference of the form with the stability of a slab is desirable to minimise slab fracture, degradation and possible failure. It is desirable that embodiments of the present invention improve form work adjacent a joint form using lost form work by providing at least one edge of the lost form work as a non-straight edge thus reducing the likelihood of cracking. The non-straight edge typically extends parallel to the joint. According to the present invention, there is provided improved form work for use adjacent a joint formed by lost form work by providing at least one edge of the lost work as a 3 non-straight edge, wherein the non-straight edge is adapted as a subsurface edge serving as an anchorage for the form work and being a plate-like flange of undulating form along its length. Preferably at least in part of the edge is a curved edge. The undulations can be uniform in amplitude and frequency. Preferably, the undulations are wave like with the edge being a flange of a plate having a fold line providing a longitudinal bend and the flange edge being displaced in alternating fashion above, below or either side of an imaginary plane of the flange coincident with the plate fold line and the imaginary plane of the flange before displacement, the displacement being 5-20* with 100 being preferable. In one preferred embodiment the flange is formed as an undulating flange set at about 1200 to a vertical plate when the plate is in situ. Preferably, the non-straight edge is part of a joint comprising a first longitudinal vertically positioned joint plate and an anchor plate connected to the joint plate, the anchor plate extending along the joint plate and having an oblique flange projecting from the joint plate, the flange having the non-straight edge. Typically, the flange has spaced openings and the flange has an undulating edge. In this form the spaced openings facilitate alternating displacement of the flange out of the plane of the flange on opposite sides of the plane of the flange. Preferably, the joint plate has dowel openings spaced along the joint plate. Preferably the joint plate has stake receiving means spaced along the joint plate. The stake receiving means are typically spaced U-shaped stake plates having end flanges projecting from a connecting web, the web being fastened to the joint plate opposite the anchor plate, the stake plate flanges having openings to receive a threaded stake, the stake having at least one flat, so that upon rotation of the stake the stake thread engages the opening and 4 is secured in the opening. Thus the height of the joint plate may be adjusted along the spaced stakes. Typically, the joint plate and the anchor plate abut and have upper oppositely extending aligned flanges forming an upper contiguous edge for the joint. Typically, the joint plate upper flange and anchor plate upper flange have respective return flanges. The present invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Figure l is a section through a joint; Figure 2 is an isometric view of a typical joint form suitable for use in a joint; Figure 3 is an enlarged view of the end of the drawing of Figure 2; Figures 4 to 7 are respective end, top, front and partial side views illustrating a typical anchor plate for use in a joint.

5 Referring to the drawings and initially to Figures 1 to 3 there is illustrated a joint 10 between two adjacent concrete slabs 11 and 12. The joint is formed by first pouring slab 12 using the joint form 13. The joint form 13 is lost form work and employs a joint plate 14 and an anchor plate 15 secured by rivets 16 5 to the joint plate 14. Dowel sleeves 17 are located at intervals along the joint plate. The dowel sleeves 17 take a square dowel plate 18 with the joint plate intersecting a diagonal of the dowel plate corner to corner. Stakes 19 pass through holes 20 in U-shaped stake plates 22 fastened to the joint plate with rivets. 10 The stake holes 20 and 21 are elongate. The stakes are threaded and are flattened so that upon rotation with a suitable tool the thread engages the long edge of the holes 20 and 21 so that the joint form may be "locked" to the stake in order to set height. The joint plate has a bottom flange 23 and a top flange 24 with a return 15 flange 25. The anchor plate has a top flange 26 and a return flange 27. The flanges 23 and 26 are aligned and appear exposed in the finished slab. The anchor plate is shown in more detail in Figures 4 to 7 and has a web 28 and an anchor flange 29 formed as a non-straight edge 30. The non-straight edge is formed by providing cut-outs 31 in the flange and displacing the edge by 20 bending at every second tab 32 to displace the edge by about 100 to the flange fold line 33 to form an undulating edge as depicted. The undulating edge has less impact on the stability of the slab when compared to the edge if it were left straight.

6 While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments. 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 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. 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 common general knowledge in the field of endeavour to which this specification relates.

Claims (14)

1. Improved form work for use adjacent a joint formed by lost form work by providing at least one edge of the lost work as a non-straight edge, wherein the non-straight edge is adapted as a subsurface edge serving as an anchorage for the form work and being a plate like flange of undulating form along its length.

2. Improved from work according to claim 1, wherein the edge of the flange has undulations.

3. Improved form work according to claim 2, wherein the undulations are substantially uniform in amplitude and frequency along the edge.

4. Improved form work according to any one of the preceding claims, wherein the flange has a fold line providing a longitudinal bend and the flange is displaced in alternating fashion above, below or either side of an imaginary plane coincident with the fold line and the plane of the flange before displacement.

5. Improved form work according to claim 4, wherein the displacement is 5-200 out of the imaginary plane of the flange.

6. Improved form work according to claim 4 or claim 5, wherein the angle between the flange and a vertical plate is substantially 120* when the plate is in situ.

7. Improved form work according to any one of the preceding claims, wherein the non straight edge is adapted to be part of a joint comprising a first longitudinal vertically positioned joint plate and an anchor plate connected to the joint plate, the anchor plate extending along the joint plate and having said flange projecting from the joint plate.

8. Improved form work according to any one of the preceding claims, wherein the flange has spaced openings.

9. Improved form work according to claim 7 or claim 8 when dependent thereon, wherein the joint plate has dowel openings spaced along the joint plate.

10. Improved form work according to any one of claims 7 to 9, wherein the joint plate has stake receiving means spaced along the joint plate.

11. Improved form work according to claim 10, wherein the stake receiving means comprises spaced U-shaped stake plates having end flanges projecting from a connecting web, the web being fastened to the joint plate opposite the anchor plate, the stake plate flanges having openings to receive a threaded stake, the stake having at least one flat, so that upon rotation of the stake the stake thread engages the opening and is secured in the opening.

12. Improved form work according to claim 7 or any one of claims 8 to 11 when dependent thereon, wherein the joint plate and the anchor plate abut and have upper oppositely extending aligned flanges forming an upper contiguous edge for the joint.

13. Improved form work according to claim 7 or any one of claims 8 to 12 when dependent thereon, wherein the joint plate upper flange and anchor plate upper flange have respective return flanges.

14. Form work substantially as described with reference to the accompanying drawings and/or Examples.