JOINT ASSEMBLY

FIELD OF THE INVENTION

THIS INVENTION relates to a support system for a joint assembly and in particular but not limited to a support system for an expansion joint assembly supporting an alignment dowel in an expansion joint of a concrete footpath or the like. The invention also relates to a kit for a joint in concrete.

BACKGROUND TO THE INVENTION

Concrete slabs are prone to movement due to thermal effects and loading. The resulting movement can be detrimental to the slab giving rise to unsightly surface cracking or in worse case situations relative vertical shifting of adjacent sections of the slab. This is often seen in footpaths where even a small shift can create an unsafe situation for pedestrians particularly the aged and infirm.

Historically, problems concerned with maintaining the integrity of concrete slabs is not a new thing, it being usual to provide some form of controlled cracking to induce subsurface cracking. Typical methods involve a surface saw cut or crack inducer pushed into the surface. On order to prevent misalignment of slabs, dowelled joints are the norm as is some form of seat or cradle to keep dowels straight before the concrete is poured. Dowels must be released from one of the slabs and it is usual to grease the dowel or have one end in a sleeve. These arrangements are all common in the art and the art is well developed so a prior art search reveals a plethora of dowel forms and cradle arrangements to support the dowels across a joint whether it be an expansion or contraction joint. They all serve to keep the dowels straight and at least one end released. The

following are examples which are by no means exhaustive being merely a representative sample of the types of dowel supports and aligners known in the prior art.

The following were located in the PCT Article 15/5 search and the inclusion herein should not be considered as any admission that any of these documents are common general knowledge in the art. The applicant considers these are merely exemplary of the wide variety of the prior art to the extent that the present invention, being a simple one, should not be viewed as obvious, but rather as inventive in a highly developed art it being more difficult to invent in an art that is so highly developed.

Australian Patent 746561 to UNDERWOOD describes a dowel alignment device in the form of a two part hinged dowel cover that clips into a metal key joint and houses a dowel. The dowel is able to slide in the cover. The cover has an eyelet at its end and a stake may be driven through the eyelet into the ground. A wedge is used to secure the stake once the dowel is level. Thus the stake may be used to keep the dowel cover and hence the dowel in position. The dowel is not a snug fit inside the cover so there is room for some transverse movement if the dowel is not perfectly straight.

Australian Patent 602108 to REEVES describes a dowelled metal key joint where the key joint has a ground engaging flange and opposite ends of a close fitting dowel are supported by bar chairs. This combination keeps the key joint upright and the dowels in parallel spaced relation. Since there is no cover, the dowels have to be greased to prevent bonding to the concrete.

US Patent 6,210,070 to SHAW et al describes parallel spaced dowel covers mounted on a continuous wire chair frame which extends along one side of a joint, dowels are inserted in the covers which permit slip and the other ends of the dowels are supported by plastics bar chairs on the other side of the joint. Thus, as long as the subsurface is level, the frame set parallel to the joint and the right distance from the joint, the dowels will be automatically aligned.

US 3,054,565 to NETTLETON describes an expansion joint kit where an L-shaped dowel has vertical and horizontal sections, the horizontal section passes through a hole in a joint plate and the horizontal section has a threaded end held in a cover so it may slip in the cover. The cover is connected to the joint plate and a nut is screwed onto the threaded end of the dowel inside the cover. Resilient material is located inside the cover outboard of the nut and this is compressed as the concrete moves and the dowel and nut is forced against the resilient material. The cover has slots receiving tabs of a vertical extension forming a chair. Thus there is a full dowel cover extending from the metal joint plate out to include the end of the dowel, the nut and the resilient material. The position of the dowel relative to the joint is set by a flange on the horizontal section which abuts against the joint plate on the side opposite the cover. The position of the dowel and cover is set by the flange. US Patent 4,578,916 to WITSCHI describes a dowel cover welded to two spaced loops of reinforcing steel. The dowel cover is held in operative position by the loops which sit on the substrate. A corresponding metal dowel is welded to two spaced loops in the same fashion and may slide inside the cover with the

four loops supporting the whole assembly. The cover and dowel loops are positioned on opposite sides of the joint respectively.

US Patent 2,508,443 to CARTER describes a joint where a dowel is supported at both ends by a dowel cover and which in turn is supported by a wire chair shaped into a clip so that one end of the dowel cover clips into place. The wire chair is secured to a ground engaging wire which extends parallel to the joint. The ground engaging wire is secured to the road base using staples.

While these arrangements are particularly suited to long joints they are not suited to joints in narrow pathways including footpaths, sidewalks and bikeways and so one.

As stated above there are many and varied arrangements for keeping a dowel and cover or sleeve aligned. The present invention has as an object, to at least provide the public with a useful alternative to the prior art in a highly developed field. It is further object of the invention to provide a dowel support assembly and joint having greater flexibility in terms of variations in dowel placementthan previously known particularly for pavements including pedestrian malls, sidewalks or footpaths, bikeways and so on.

OUTLINE OF THE INVENTION

In one aspect there is provided a pavement as a sidewalk, footpath or bikeway, laid while wet and allowed to harden comprising a series of spaced transverse divider strips dividing the pavement into sections of predetermined length, each divider strip comprising a dowelled joint having dowel sliding in a dowel sleeve, the dowel sleeve being supported in predetermined position by a

dowel sleeve stand. The divider strips typically comprise joint plates and the dowel and dowel sleeve project from the dowel plate.

In onefurther aspect the present invention resides in a support system for a joint assembly of the type comprising a joint plate adapted to be located adjacent an expansion joint in a concrete structure, the plate being adapted to carry a dowel passing through the plate and a dowel sleeve projecting from the plate, the system comprising a stand having a plurality of dowel sleeve positioning means whereby the stand locates adjacent and supports a projecting end portion of the dowel sleeve in its operative position relative to the joint plate. In another aspect the present invention resides in a joint assembly comprising a joint plate located adjacent an expansion joint between concrete slabs, the plate carrying a dowel passing through the plate and set in a dowel sleeve, the dowel sleeve having an end portion, a dowel sleeve in support comprising a stand having a plurality of dowel positioning means whereby the stand locates adjacent and supports the projecting end portion of the dowel sleeve in its operative position relative to the joint plate.

In a further aspect the invention resides in a dowel stand comprising a base, an upright and projecting tabs or fingers which locate inside or about a dowel sleeve. In a further aspect the invention resides in a kit for a joint assembly.

Preferably, the kit comprises dowel stands, dowel sleeves and joint plates, the joint plates having a dowel sleeve locator and the dowel stand having dowel sleeve end supports adapted to support dowel sleeves at selectable heights. The

kit typically includes joint plates of different widths, each joint plate having a dowel sleeve locator matched to the selectable heights.

Preferably the joint plate includes a dowel sleeve locator enabling the dowel sleeve to be automatically located in position relative to the particular joint plate. The dowel sleeve locator typically comprises a channel extending along the joint plate. The channel is typically T-shaped in profile and the dowel sleeve has a correspondingly shaped head which is held captive in the channel and against transverse movement.

The stand typically comprises a base, an upright and projecting tabs or fingers which locate inside or about the dowel sleeve. The stand may be configured for a single dowel sleeve positioned centrally in a slab or it may be made to cater for dowel sleeves set a different heights. This means the one stand may have multi-dowel supports and be used for different concrete thicknesses where the dowel sleeve is still centrally placed in the concrete by reason of the stand having different dowel positions. The different positions of the dowel sleeves may be provided by tabs which fit inside and outside an open- ended sleeve. Preferably, at least one tab includes a frangible spacer element or stopper adapted to abut against a dowel end to provide a movement void whereby the frangible element may flexor break in response to dowel movement within the dowel sleeve caused by slab expansion.

The dowel sleeve typically comprises a tubular member, the tubular member is typically secured in its operative position by reason of a support additional to the stand, the additional support comprising a stake passing through a stake receiving means in the dowel sleeve and driven into the ground

or like adjacent an opposite end of the sleeve and near to the joint plate, thus the stand and stake are at opposite ends of the dowel sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the present invention may be more readily understood and be put into practical effect reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein:- Figure 1 is a cross-section through a typical concrete structure; Figure 2 is a perspective drawing of a typical stand; Figure 3 is a perspective drawing of a typical joint plate; and Figure 4A and Figure 4B are respective cut away and end views of a typical dowel sleeve.

METHOD OF PERFORMANCE

Referring to the drawings and initially to Figure 1 there is illustrated a concrete construction 10 which is in this case is part of a footpath where an expansion joint 11 is formed by a compressible material 12 and a joint plate 13 abutting against the compressible material 12. Relative movement of the slabs is controlled by a dowel 14 projecting into slab 15 and into a dowel sleeve 16 in slab 17. It will be appreciated that as the slabs 15 and 17 expand and contract they are controlled in terms of movement by reason of the use of the dowel and its ability to travel inside the dowel sleeve 16 in the usual way.

The dowel sleeve 16 is held in its operative position prior to pouring the slab 17 by a stand 18 at one end, a stake 19 at the other end and its head portion 20 being positioned inside and held captive in a channel 21 of the joint plate 13. This holds the head against sideways movement. So that there is room

for thθ dowel to move the stand 18 includes a plurality of projecting tabs 22 as well as frangible fingers 23 and 24, the fingers 23 and 24 abut the dowel and ensure there is a space to cater for dowel movement once the slabs have been poured by being able to flex or break. Details of the stand 18 are shown in greater detail in Figure 2.

Referring now to Figure 2, the stand 18 includes a base 45 and eight tabs 22 arranged so that the stand may be utilised with a dowel sleeve positioned at one of three different heights. This means the stand illustrated may be used to cater for slab thicknesses of 75mm, 100mm and 125mm as will be usual options in a footpath while keeping the dowel central in each case. It will be appreciated that in each case although the stand 18 is adapted to fit different thicknesses of footpath, a different joint plate 13 would be employed in each case so that the dowel is located centrally in the slab. In the case of the 75mm thick slab only one of the frangible fingers 23 will be located inside the dowel sleeve at that position and in the case of the 125mm slab only the frangible finger 24 will be located inside the dowel sleeve.

Thus it will be appreciated that the end of the dowel shown at 26 in Figure 1 would be automatically positioned relative to the joint at the desired depth and also the opposite end of the dowel will be automatically positioned within the slab 15.

By reason of the use of the stand in the channel 21 and the stake 19 which passes through a hole in the dowel sleeve, the dowel may be easily positioned at right angles to the joint. Where a number of dowels are employed these may also be located and secured in parallel so that there is little likelihood

of tension being created in the slab by reason of the use of the dowels due to the ability to properly position the dowels prior to the concrete being poured and also to keep them secure during the pour and finishing procedure.

Referring now to Figures 3, 4A and 4B, the joint plate 13 is illustrated in greater detail. The joint plate includes the channel 21 which is generally T- shaped in cross-section so that it holds the matching flange 27 of the dowel sleevel 6. The plate has upper and lower flanges 28 and 29, flange 28 providing a surface finish.

The dowel sleeve 16 includes a flange 30 having a through hole 31 through which the stake 19 passes, the dowel sleeve effectively comprising a hollow tube section 32 opened at opposite ends so as to operate as shown in Figure 1.

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 out in the appended claims. For example, where "comprising" is used it is not intended to be exclusive but the features listed are the minimum and additional features added to the combination is still within the scope of the invention described and claimed.