AU8422998A - Improvements in dowels for slabs - Google Patents

Description

r7,7--- -lr- P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "IMPROVEMENTS IN DOWELS FOR SLABS" The following statement is a full description of this invention, including the best method of performing it known to us: THIS INVENTION relates to improvements in dowels for slabs.

In particular, the invention is directed to a cover for the dowels in concrete slabs.

Conventionally, dowels extend through the key joints between adjacent concrete slabs as disclosed in AU-A-48188/96 (DANIEL CHARLES UNDERWOOD) and WO 94/29538 (PCT1AU94100295) (WALTER PLEHANOFF). It is conventional .practice that the exposed portions of the dowels, extending into the area in which the second slab is to be poured, are coated with grease or the like to enable slip between the dowels and the concrete slab when the latter is cast to accommodate thermal expansion.

As the exposed portions of the dowels are liable to be stepped on or struck, they can be easily bent and so not lie substantially perpendicular to the key joint.

It is an object of the present invention to provide a support for a dowel for a concrete slab including: a tubular body closed at one end and open at the other end and arranged to receive a portion of a dowel extending from a slab; and clip means adapted to engage a reinforcing bar or rod interconnecting a plurality of the supports to maintain the supports in Sa predetermined configuration.

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i Preferably, the inner face of the closed end of the tubular body has at least one deformable spigot, eg., 8mm long, adapted to be compressed by the adjacent end of the dowel when the dowel undergoes thermal expansion.

Preferably, the clip means has at least one pair of opposed, resilient fingers adapted to releasably engage reinforcing rods of different thickness therebetween.

Preferably, a cap member is releasably engageable in the open end of the tubular body and has a plurality of flexible fingers or 10 segments adapted to support dowels of different diameters.

To enable the invention to be fully understood, a preferred embodiment will now be described with reference to the accompanying drawings in which: FIG 1 is an isometric view of the support; FIG 2 is a perspective view showing a pair of the supports in use with a key joint plate; and FIG 3 is a sectional side elevation of one of the supports, supporting a dowel after a slab has been laid.

The support 10 is adapted to be used with a dowel 100 extending from a key joint (not shown), the other end of the dowel being embedded in a concrete slab 200 which has been cast (see FIG.

A plurality of the dowels 100 may extend substantially perpendicularly to the key joint 101 and be arranged at preferably I r equally spaced intervals (see FIG. 1).

The support 10 has a tubular body 11 with an open mouth 12 at one end. An end wall 13 closes the other end of the tubular body 11 and has a plurality of compressible spigots 14 which extend into the interior of the tubular body 11 by a distance of, eg., 8mm.

A clip assembly 20 is formed integrally with the tubular body 11 has a pair of resilient arms 21, 22 arranged in opposed spaced relationship to form holes 23 adapted to releasably engage a length of reinforcing rod 110.

In use, the tubular bodies 11 of the supports 10 are engaged on the exposed portions of the dowels 100 and the clip assemblies 20 are engaged with the reinforcing rod 110 to maintain the desired spaced relationship between the adjacent dowels 100, ie., 15 to prevent or minimise any bending or deformation of the dowels I should they be struck.

The tubular body 11 may be dimensioned with an internal diameter of, eg., 27mm to receive a dowel 100 having an external diameter of, eg., To enable the support 10 to be used with dowels 100 of reduced diameter, eg., 8, 16 or 18mm, a cap member 30 is attached to the tubular body 11 by a strap (not shown) and is engageable in the mouth 12, and has a body 31 surrounding an annular flange 32. A plurality of segments 33 are moulded integrally with the cap body 31 and flange 32 and are adapted to be deformed inwardly by the dowel 100 when the support 10 is located on the dowel 100.

It will be readily apparent to the skilled addressee that by securing the dowels 100 to the reinforcing rod 10 via the supports the likelihood of the dowels 100 being bent or deformed is greatly minimised.

The clearance between the dowel 100 and the tubular body 11 (and flange body 31) enables thermal expansion or contraction of the dowel 100, the expansion being further accommodated by the compression of the spigots 14.

Preferably, the support and the cap are moulded from suitable plastics material, eg., of the type used to manufacture bar chairs.

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

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Claims (8)

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3. 15 iada 0. laims defining the invention are as follows: A support for a dowel for a concrete slab including: a tubular body closed at one end and open at the other and arranged to receive a portion of a dowel extending from a and clip means adapted to engage a reinforcing bar or rod connecting a plurality of the supports to maintain the supports in determined configuration. A support as claimed in Claim 1 wherein: the inner face of the closed end of the tubular body has east one deformable spigot, adapted to be compressed by an cent end of the dowel when the dowel undergoes thermal Insion. A support as claimed in Claim 1 or Claim 2 wherein: the clip means has a pair of opposed, resilient fingers pted to releasably engage reinforcing rods of different thickness ebetween. 3.' ther

4. A support as claimed in Claim 3 wherein: the clip means has a body extending transversely of the tubular body, and a respective pair of the fingers are provided at each end of the clip body.

A support as claimed in any one of Claims 1 to 4 wherein: 7 a cap member is releasably engageable in the open end of the tubular body and has a plurality of flexible fingers or segments adapted to support dowels of different diameter.

6. A support as claimed in any one of Claims 1 to wherein: the support is moulded integral', in plastics material.

7. A support for a dowel for a concrete slab substantially as hereinbefore described with reference to the accompanying drawings.

8. A method for supporting a dowel in a slab substantially 10 as hereinbefore described with reference to the accompanying drawings. DATED this fifteenth day of September 1998. 15 CONNOLLY KEY JOINT PTY LTD, By its Patent Attorneys, FISHER ADAMS KELLY.