AU714110B2 - Insert for concrete structures - Google Patents

Description

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AUSTRALIA

Patents Act 1990 DIVISIONAL SPECIFICATION FOR A STANDARD PATENT Name of Applicant: Actual Inventor(s): Address for Service: Invention Title: Details of Associated Patent Application No: DANIEL CHARLES UNDERWOOD Daniel Charles Underwood

INTELLPRO

Patent Trade Mark Attorneys Level D, 308 Edward Street BRISBANE, QLD, 4000 (GPO Box 1339, BRISBANE, 4001) Insert for Concrete Structures Australian Patent No. 48188/96 filed 21 March 1996 The following statement is a full description of this invention, including the best method of performing it known to me: "INSERT FOR CONCRETE STRUCTURES" TECHNICAL FIELD OF THE INVENTION THIS INVENTION relates to an insert for concrete structures and in particular to concrete structures with to key joints and inserts.

BACKGROUND

ART

At present, large floor areas of concrete are laid as slabs separated by key joints which allow relative movement between adjacent slabs while maintaining the slabs in alignment. Present key joints and the associated slabs employing the key joints have a number of undesirable features. For example, present key joints OoO 10 require skill to align and adjust their position and it would be desirable to provide key joint which can be positioned using simplified procedures. Another *.oo problem arises due to stresses formed in adjacent slabs resulting in cracking or fractures forming adjacent the key joint. It would be desirable to reduce the likelihood of cracking or fracturing by improving the key joint and thereby improve the structure of the slab.

'.".OUTLINE OF THE INVENTION In one aspect, the present invention resides in an insert for preventing concrete from flowing into a space between a stake and a key joint supported by the stake, the insert comprising key joint or stake coupling means and filler means so that the insert can be coupled to an assembled key joint and stake to inhibit flow of wet concrete into the space between the key joint and the stake.

Advantageously, the insert is typically elongate and generally U-shaped in section having a bridging portion and depending opposed flanges so that the insert can bridge over a stake with the flanges abutting against the key joint in 3 order to inhibit flow of wet concrete into the space between the stake and key joint. Advantageously, the flanges includes flexible edge portions so that the flange can sealingly deform against the key joint when the insert is coupled in place. This also allows for the flanges to be made deep enough to cater for a range of spaces between the stake and the key joint. In this embodiment, the flanges are flexible enough to flare outward for smaller spaces.

The coupling means can be any suitable arrangement which enables the S: insert to be fitted in place and embraces simple wedging actions to more complex clip action couplings. Advantageously, the coupling means comprises a hand insertable press fit clip enabling the insert to be clipped onto the stake.

BRIEF DESCRIPTION OF THE DRAWINGS :•ooo• In order that the present invention can be more readily understood and be put into practical effect, reference will now be made to the accompanying drawings and wherein:- Figure 1 is a pictorial view illustrating a key joint for use with an insert according to the invention; Figure 2 is a pictorial view illustrating a partially completed concrete construction incorporating an insert according to the present invention; Figure 3 is a pictorial view illustrating a stake for use with an insert according to a preferred embodiment of the present invention; Figure 4 is an enlarged view of a portion of the stake of Figure 3; Figure 5 is an end view of the stake of Figure 3; Figures 6 and 7 are pictorial views illustrating use of the stake of Figure 3; Figure 8 is a pictorial view illustrating one preferred embodiment of an 4 insert according to the present invention; and Figure 9 is a sectional view illustrating a preferred insert according to the invention showing the insert coupled to a stake.

METHOD OF PERFORMANCE Referring to the drawings and initially to Figure 1, there is illustrated a key joint 10 comprising a folded sheet of metal having a channel 11 and on its opposite side a projection 12. The key joint 10 includes a plurality of square Sapertures 13, each aperture having a horizontal edge 14 so that a square section *o.oo dowel passing through an aperture 13 will have one of its flat surfaces located in a horizontal plane. The apertures 13 can be punched into the metal as "knock- .i outs" 13' (see Figure 6) or can be partial "knock-outs" in the form of hinged o..

closures that can be set at 90' to the key joint to provide a horizontal seat to which a dowel passing through the aperture can be secured.

Referring to Figure 2, there is illustrated a partially completed concrete structure 15 employing the key joint 10 of Figure 1. As can be seen, the structure 15 comprises a horizontal slab of concrete 16 having the key joint 10 defining an edge of the slab 16. A plurality of square section dowels 17 are shown projecting from the slab at spaced intervals along the slab. The key joint 10 is retained in place prior to pouring the slab 16 using stakes 18 which pass through opposed elongate apertures 19 in the key joint and are embedded in the ground beneath the slab. The inclusion of the stake 18 serves to provide a simplified key joint layout and a more stable layout of key joint and dowels prior to pouring the slab 16. Details of the operation of the stake 18 will be described below.

Figure 2 shows dowels 17 capped with a cap 20 which can be made from expanded polystyrene foam or other compressible filler so as to create a concrete free gap 21 beside each dowel 17. Three dowels 17 are illustrated in Figure 2, one in phantom along with a phantom cap 20, one with the dowel and cap fitted and one with the cap omitted. The caps 20 can be applied to the dowels on both sides or on one side of the key joint only. The phantom outline serves to illustrate the arrangement on both sides.

As can be seen, the slab 16 can partially cure prior to an adjacent slab .which will embrace the projecting dowels being poured. As the two slabs cure at different rates, relative displacement of the dowels will be accommodated by the gaps 21 or compression of the filler provided by the caps Referring to Figures 3 to 5, there is illustrated a stake 18 according to a preferred embodiment of the present invention, the stake 18 comprises a cylindrical steel rod having a shank portion 22 which can be driven into the ground and locking means 23 including a plurality of selectable locking sites in the form of a plurality of grooves 24 which are opposed and offset (see Figure 4).

The locking means 23 includes opposed flats 25 so that the stake can freely slide through the elongate apertures 19 in a key joint 10 but on rotation, edges of the elongate apertures 19 frictionally engage in the grooves 24. The grooves 24 are radiused as shown in phantom at 26 in Figure 5 so that edges of the elongate apertures 19 in the key joint 10 suffer minimum deformation as the stake 18 is rotated to lock the stake 18 to the key joint Referring to Figures 6 and 7, use of the stake 18 is illustrated. In use, the stake 18 is first driven into the ground with a key joint 10 slid over the top so it sits on the shoulder 27 (see Figure 3) of the stake 18 at the transition from the 6 flats 25 to the shank 22. As can be seen in Figure 6, the key joint 10 includes a pair of elongate apertures 19 through which the stake 18 passes from below.

A plurality of stakes 18 are inserted through the key joint in this way so the key joint 10 is supported by stakes 18 at spaced locations along the key joint Once all the stakes 18 are in place in their released position, as shown in Figure 6, an operator can then slide the key joint 10 to its desired position on each stake 18 and lock the key joint 10 to the stake 18 by rotating the stake 18 using a suitable tool.

It will be appreciated that any form of locking means 23 can be employed.

10 For example, the locking means 23 could comprise a knurled surface so that as o° the stake 18 is driven through the key joint 10, the elongate apertures 19 are eo deformed to automatically engage the knurled surface. Furthermore, although the stake 18 is shown locked to both elongate apertures 19, it need only lock with *one of the elongate apertures 19.

In the illustrated embodiment, the stake 18 is of constant diameter throughout, thus requiring the key joint 10 to be slid over the stake 18 from above but this need not be the case. For example, the opposed flats 25 could be flattened using a rolling process and made wider so that the cylindrical shank portion 19 and the opposed flats 25 could both be made to pass through the elongate apertures 19 while the stake 18 is in the position illustrated in Figure 6 prior to rotation to the position illustrated in Figure 7.

Referring to Figure 8, there is illustrated a key joint assembly 28 employing a key joint 10, a stake 18 supporting the key joint 10 in a generally vertical attitude and an insert 29 according to a preferred embodiment of the present 7 invention. The insert 29 is extruded from a plastics or rubber material and includes a body 30 which is generally U-shaped in transverse section. The insert 29 is shown in phantom in its operative position clipped onto the stake 18 by elongate clip 31 (see also Figure 9).

The insert includes flexible flanges 32 which, as shown in phantom, flare out against the key joint when the insert is in place (see also Figure 9).

Figure 9 illustrates in phantom the flaring action of the flexible flanges 32 when the insert is used with a smaller key joint *There are of course, many other mechanically equivalent inserts including 10 wedging inserts which can fill a space 33 behind the stake 18 rather than create o° a cavity as in the illustrated embodiment. Moreover, while the illustrated embodiment describes a hand insertable insert, inserts that are placed with the assistance of a tool, for example driven into place with a hammer, are also within the scope of the present invention.

Whilst the above has been given by way of illustrative example of the present invention, many variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as set forth in the appended claims.

Claims (9)

1. An insert for inhibiting concrete flowing into a space between a stake and a key joint supported by the stake, the insert comprising key joint or stake coupling means and filler means arranged so that the insert can be coupled to an assembled key joint and stake to inhibit flow of wet concrete into the space between the key joint and the stake.

2. The insert according to claim 1 wherein the insert is elongate and generally U-shaped in section having a bridging portion and depending opposed flanges so that the insert can bridge over a stake with the flanges abutting against the key joint in order to inhibit flow of wet concrete into the space between the stake and key joint.

3. An insert according to claim 2 wherein the flanges include flexible edge portions so that the flanges can sealingly deform against the key joint when the insert is coupled in place. -090

4. The insert according to claim 3 wherein the flanges having a depth sufficient for a range of spaces between the stake and the key joint.

5. The insert according to claim 3 or claim 4 wherein the flanges are flexible enough to flare outwardly for smaller spaces.

6. The insert according to any one of the preceding claims wherein the coupling means is arranged for fitting in place by wedging or clipping.

7. The insert according to any one of the preceding claims wherein the coupling means comprises an insertable press fit clip enabling the insert to be clipped onto the stake. 9

8. A partially completed concrete structure comprising a generally horizontal slab of concrete having, at least one key joint support by one or more stakes, and coupled to the or at least one of the one or more stakes is the insert according to any one of claims 1 to 7.

9. An insert substantially as described with reference to the drawings. DATED this 1 9 th day of October, 1999. DANIEL CHARLES UNDERWOOD By his Patent Attorneys INTELLPRO