AU730480B2 - Improvements in key joints for slabs - Google Patents

Description

it i P/00/01Il Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "IMPROVEMENTS IN KEY JOINTS FOR SLABS" The following statement is a full description of this invention, including the best method of performing it known to me: (I (ti 2 THIS INVENTION relates to improvements in key joints for slabs.

Because concrete undergoes thermal expansion and contraction, it is necessary to provide expansion joints or breaks in concrete slabs, footpaths and the like to at least minimise unwanted cracking in the concrete.

For example, it is common practice to provide expansion joints or break lines every 1.0 to 1.5 metres along footpaths.

Many different key joint systems have been disclosed 10 where a joint plate is supported by a plurality of spaced stakes. It is necessary that vertical adjustment is possible between the joint plate and the stakes so that the height of the plate can be selectively adjusted.

Examples of adjustable connection between the plate 15 and the stakes is disclosed in US 4411404 and US 4455104 (ALBERT P. WEISBACH); AU-B-36515/89 (604612) (PAUL F. CONNOLLY et al) and AU-B-28152/92 (666883) (DANIEL C. UNDERWOOD). In the US Patents of WEISBACH, the top end of each stake is flattened and has a plurality of closely spaced, vertically arranged serrations formed on one side to releasably engage the hem of a downturned flange on the joint plate, the edge of the hem serving as a locking pawl for cooperating with the serrations. In AU-B-36515/89, wedges are engaged between a central portion of the plate and respective stakes to releasably lock the plate to the stakes. In AU-B-28152/92 (UNDERWOOD), the stakes pass through pairs of aligned, elongate apertures in the plate and are rotatable through 90° so that formations on the sides of the stakes releasably engage sides of the apertures to secure the plates to the stakes.

It is an object of the present invention to provide alternative means for releasably securing the stakes to the key joint plate.

It is a preferred object of the present invention to provide 10 such means which allow easy adjustment of the plate to the stakes when the key joint assembly is being set up which will prevent accidental or unwanted adjustment of the plate relative to the stakes.

o It is a further preferred object of the present invention to o"e" provide stakes which can be adapted to suit a wide range of 15 applications, eg., where a slab is to be poured on an existing slab.

Other preferred objects of the present invention will become apparent from the following description.

Throughout the specification, the term "a keyed joint plate assembly for concrete of the type hereinbefore described" shall include: "a joint plate having substantially co-planar, vertical top and bottom sections interconnected to a rearwardly-spaced central section by rearwardly-convergent upper and lower inclined sections, a plurality of pairs of holes spaced along the plate, the holes from each pair being provided respectively in the upper and lower inclined sections in substantially vertical alignment to each other, and a substantially horizontal top edge; and a plurality of stakes to support the plates substantially vertically, each stake passing through a respective pair of the vertically aligned holes." Such definition is based on Claim 1 of parent Patent No. 604612.

In a broad aspect, the present invention resides in a S. 10 keyed joint plate assembly including: a keyed joint plate assembly as hereinbefore described wherein: each stake is formed integrally with, or associated with, a foot plate located below the bottom section of the joint plate; and 15 a pair of opposed wedge means are engaged between the foot plate and the bottom section of the plate.

o Preferably, the stake means may extend through an aperture or slot in the foot plate for sandy or loose soil) or may be terminated at the foot plate, eg., for use on very hard soils or where the slab is to be laid on an existing slab.

Preferably, at least one of the holes may have an integral resilient finger means adapted to urge the stake towards the central section of the plate.

I i) To enable the invention to be fully understood, a preferred embodiment will now be described with reference to the accompanying drawings in which: FIGS 1 and 2 are respective rear and front perspective views of the keyed joint assembly of a first embodiment; and FIG 3 is a sectional end view of the joint plate of the first embodiment.

Referring to FIGS 1 to 3, the joint plate 310 has respective, substantially co-planar, vertical top and bottom sections 10 311 and 312 interconnected to a planar central section 313 by rearwardly convergent upper and lower inclined sections 314, 315.

Aligned holes 316, 317 are formed in the inclined portions 314, 315 to receive a stake 320, the upper hole 316 having a resilient finger 318 adapted to urge the plain shank 322 of the stake 320 towards 15 the central section 313.

A foot plate 330 is placed beneath the joint plate 310 and the stake 320 extends through a slot 331 in the foot plate.

A pair of opposed wedges 340 are placed on the foot plate 330 and by movement of the wedges relative to the joint plate 310, the height of the top edge of the joint plate 310 relative to the supporting soil 350 can be selectively set.

In a modified embodiment, not shown, the stake 320 may extend through a central hole or aperture in the foot plate 330.

i i) 6 In an alternative embodiment, eg., where the slab 360 is to be laid, eg., at a round-about on an existing work slab 350, the stake 320 may be formed integrally with the foot plate 330 (and not extend below the foot plate).

Preferably, the joint plates are roll-formed from metal strip, with safety edges top and bottom and may have reinforcing ribs in the top handle bottom sections. Alternatively, joint plates may be, eg., extruded from suitable plastics material.

The stakes may be formed from steel rod, eg., with 10 digging points at their lower end or may be moulded from suitable plastics material. Where the stake 320 and foot plate 330 are a. formed integrally, this is preferably done by moulding the two ***components together in plastics.

It will be readily apparent to the skilled addressee that 15 the joint plates may have a range of profiles.

Various other changes and modifications may be made to the embodiment described and illustrated without departing from the present invention.

Claims (4)

1. A keyed joint plate assembly as hereinbefore described wherein: each stake is formed integrally with, or associated with, a foot plate located below the bottom section of the joint plate; and a pair of opposed wedge means are engageable between the foot plate and the bottom section of the plate.

2. An assembly as claimed in Claim 1 wherein: the stake extends through an aperture or slot in the foot 10 plate for sand or loose soil, or is terminated at the foot plate for use on very hard soils or where the slab is to be laid on an existing slab.

S3. An assembly as claimed in Claim 1 or Claim 2 wherein: at least one of the holes has an integral resilient finger means adapted to urge the stake towards the central section of the 15 plate.

4. A keyed joint plate assembly for concrete substantially as hereinbefore described with reference to FIGS. 1 to 3 of the accompanying drawings. DATED this fifth day of June 2000. PAUL FRANCIS CONNOLLY and ALMA IRENE CONNOLLY By their Patent Attorneys FISHER ADAMS KELLY