AU2008207677B2

AU2008207677B2 - Contraction joints and formwork for concrete

Info

Publication number: AU2008207677B2
Application number: AU2008207677A
Authority: AU
Inventors: Mark Anthony Connolly; Paul Francis Connolly; David Boyd Taylor
Original assignee: Leviat Pty Ltd
Current assignee: Leviat Pty Ltd
Priority date: 2003-03-25
Filing date: 2008-09-02
Publication date: 2012-02-02
Anticipated expiration: 2024-03-03
Also published as: AU2009101012B4; AU2009101012A4; AU2009222558A1; AU2004200839A1; AU2009222558B2; AU2008207677A1

Abstract

TITLE: CONTRACTION JOINTS AND FORMWORK FOR CONCRETE A contraction joint member (10A, 11 0A, 210A) for concrete slabs has a body (111, 211) and a pair of vertically spaced flanges (13, 14, 5 113, 114, 213, 214), with sets of aligned holes (15, 115, 215) extending horizontally to one side of the body (111, 211) to receive stakes (17). A contraction joint member may be used as formwork for concrete slabs. C?) LO (0 N( .(...N....... .. .... ..... ... .. ... ... ... ... ... . ... .. .. .. C)? do LO) * (N C14)

Description

P/00/011 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "CONTRACTION JOINTS AND FORMWORK FOR CONCRETE" The following statement is a full description of this invention, including the best method of performing it known to us: 1 TITLE: CONTRACTION JOINTS AND FORMWORK FOR CONCRETE THIS INVENTION relates to contraction joints and formwork for concrete. 5 Contraction joints are provided between adjacent concrete slabs to accommodate the thermal contraction of the slabs as the ambient temperature varies. In extreme conditions, e.g., in full sunlight, the temperature variation over a day may be 30-40*C. If insufficient capacity for contraction is provided, the slab(s) may suffer cracking, which 10 mechanically weakens the slab(s) and is aesthetically unacceptable. There have been many types of contraction joints used in the past, but these usually have limitations, including cost of manufacture, ease of installation, and inability to be used in continuous concrete pours. SUMMARY OF THE INVENTION 15 It is an object of the present invention to provide a contraction joint member designed to avoid, or at least ameliorate the deficiencies of the known joints. Other preferred objects of the present invention shall become apparent from the following description. 20 Throughout the specification, the terms "substantially vertical" and "substantially horizontal" shall be used to describe the common orientation of a component when in use. In one aspect, the present invention resides in a contraction joint member, including: 25 a substantially vertical, planar body; at least two, vertically spaced, substantially horizontal, flanges extending from one side of the body; and a plurality of sets of aligned holes in the flanges operable to receive supporting stakes or pins; wherein: 1110583_1 2 the body and the flanges are formed from sheet metal, roll formed or folded to shape, each of the flanges being connected to an upper or lower edge of the body by a respective connecting portion lying adjacent a side face of the one side of the body; and 5 the body is non-compressible to accommodate thermal contraction of concrete slabs when separated by the body. Preferably, releasable locking means are provided between the body and/or the flanges, and the stakes or pins, to enable the vertical position of the contraction joint member, relative to an adjacent slab to be 10 poured, to be vertically adjusted. In a second aspect, the present invention resides in a formwork for concrete slabs employing the contraction joint member as hereinbefore described. Preferably, spaced holes are provided in the body of the 15 contraction joint member, to allow steel reinforcing rods and/or dowel members (used to keep slabs in vertical alignment) to extend through the contraction joint member. For use in formwork, these holes are omitted, or optionally, be provided as knock-outs. BRIEF DESCRIPTION OF THE DRAWINGS 20 To enable the invention to be fully understood, preferred embodiments will now be described with reference to the accompanying drawings, in which: FIG. 1 is a sectional end view of a first embodiment of an expansion joint member, not forming part of the invention; 25 FIG. 2 is a similar view of a second embodiment, not forming part of the invention; FIG. 3 is a similar view of a third embodiment, not forming part of the invention; FIGS. 4 and 5 are perspective views of the first embodiment 1110583_1 3 in use; FIGS. 6 and 7 are respective section end views of joints formed, corresponding to FIG. 5 and 4, respectively; FIG. 8 is a perspective view of formwork employing a 5 contraction joint, in accordance with the present invention, having a profile based on the first embodiment; FIG. 9 is a perspective view of formwork employing a contraction joint having a profile based on the second embodiment; FIGS. 10A and 10B are schematic end views of alternative 10 metal section profiles for the contraction joint member of the formwork of FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 4 to 7, the expansion joint member 15 10, not forming part of the present invention, has substantially vertical body 11 where the body has a second body portion 12 and a pair of vertically spaced, substantially horizontal flanges 13, 14 roll-formed from a single piece of galvanised sheet steel. Spaced pairs of holes 15, 16 in the flanges 13, 14 are adapted to receive stakes 17 which are releasably 20 locked relative to the expansion joint member 10 by, e.g., wedges 18 to allow the vertical height of the expansion member to be selectively adjusted. (in an alternative embodiment, not shown, the holes 15, 16 may be non-circular, and are releasably engaged by flanges or other releasable locking formations on the stakes 17.) 25 The first portion 20 of the body 11 may be formed by an elongate strip of "ABELFLEX" (Registered Trade Mark) resiliently compressible material (or other resiliently compressible elastomeric material) which is fixed to the second portion 12, eg., by contact (or other suitable) adhesive (or double-sided tape) (not shown)). The first body 1110583_1 4 portion 20 has a removable top strip 21, as illustrated in more detail in FIG. 5. In the embodiment shown in FIG. 5, the top strip 21 may be removed to leave a recess or groove 19 which may be filled with a sealant (not shown) to seal the expansion joint between the slabs CS. 5 It will be noted that the first portion 20 is of greater height (eg., by 10mm) than the second portion 12 of the body 11. For the sealed type joints shown in FIGS. 5 and 6, the expansion joint member 10 will be installed in the configuration shown in FIGS. 5 and 6 where the top edge 22 of the first portion 20 provides a screeding surface for the concrete, 10 (FIG. 6 shows the joint, after the concrete slabs have been poured, but before the top strip 21 has been removed and the sealant applied to the groove 19.) For a non-sealed type joint of FIGS. 4 and 7, the expansion plate member 10 will be used in an inverted configuration, where the adjacent top edges of the first and second portions 20, 12, will provide the 15 screeding surface. The flanges 13, 14 are offset by 10mm, relative to the centre line of the first body portion 20 and equally spaced about the centre line of the second body portion 12. The holes 23 are offset relative to the centre line of the second body portion 12, but are equally spaced about the 20 centre line of the final expansion joint. A plurality of holes 23 are provided in the second body portion 12 (and may also be provided through the first body portion 20) to allow reinforcing steel rods and/or dowels 30, to extend through the body 11. The dowels 30 may be of any suitable cross-section (eg., circular, 25 square, rectangular, thin planar). It will be readily apparent to the skilled addressee that the resiliently compressible material of the first body portion 20 will accommodate up to, e.g., 10-15mm of thermal expansion/contraction between adjacent concrete slabs CS. 1110583_1 5 Referring to the second embodiment of FIG. 2, the expansion joint member 110 has a substantially vertical body 111 with substantially horizontal flanges 113, 114, each having holes 115, 116 therethrough. 5 The body 111 is formed integrally with the flanges 113, 114 by an extrusion process, the body 111 being hollow, and divided into "zones" by resiliently compressible ribs 124. Spaced holes 123 through the body 111 allow the passage of steel reinforcing rods and/or dowels as hereinbefore described. io In the third embodiment of FIG. 3, the expansion joint member 210 again has a body 211 and flanges 213, 214 (with holes 215, 216) integrally formed by an extrusion method. The body 211 is formed of plastics material with a high percentage of void spaces (or aeration) to allow resilient compression of is the body in the horizontal direction by the adjacent concrete slabs CS. In an alternative embodiment, not shown, the body 211 may be formed by a co-extrusion, where the second body portion and flanges are integrally formed of a readily non-compressible, rigid material, eg, PVC, and the first body portion (spaced from the flanges 213, 214) are 20 formed, by co-extrusion, of the compressible (ie., aerated) material. As shown in FIGS. 1, 2, 3 and 6, a strip of tear-off tape 21A, 121A, 221A may be provided to provide a clear joint line. In addition, as shown in FIGS. 2 and 3, a tear-off moulding strip 121, 221 may be provided on the body 112, 212, to enable the 25 expansion joint members 110, 210 to be used in the preparation of sealed joints. As shown in FIG. 8, by omitting the compressible material of the one body portion 20 and the holes 23, the roll-formed metal section (12, 13, 14) can be employed as a contraction joint member used in 1110583_1 6 formwork 10 A for the pouring of concrete slabs. Each flange 13, 14 is connected to an adjacent upper or lower edge of the body 12 by a respective connecting portion 13A, 14A, where each lies adjacent the side face 12A of the body 12. 5 Similarly, as shown in FIG. 9, by the omission of the holes 123, through the body 111, the expansion plate member 110 of the second embodiment can also be used as external formwork 11 QA for the casting of concrete slabs. (It will be readily apparent to the skilled addressee that the expansion joint member 210 of the third embodiment 1C of FIG. 3 can be similarly modified for use as external formwork.) FIGS. 10A and 10B show alternative roll-formed profiles of the roll-formed metal sections 1OB, 10C of the contraction joint member of the first embodiment and of the corresponding formwork. In these alternatives, the flanges 13B, 14B, 13C, 14C are roll-formed intermediate 15 the adjacent portions of the second body portion 12B, 12C, rather than as "edge" flanges as in FIG. 1. By omitting the compressible material of the one body portion 20, the roll-formed section can be used in a contraction joint, e.g., to control shrinkage cracking. 20 In the other alternative embodiments described and illustrated, the expansion joint member can be connected to a contraction joint member by substituting rigid (or semi-rigid) material for the compressible material in the joint member body. The specific profiles illustrated are by way of illustrative 25 examples only and their specific shapes are not essential to putting the invention into effect. In addition, the profiles may be formed, e.g., by folding or other suitable metal-working techniques, in addition to roll-forming. The present invention provides contraction joint members, 1110583_1 '7 and/or external formwork, for concrete slabs, which are relatively inexpensive to manufacture, easy to install, and readily adaptable to a wide range of intended applications. Various changes and modifications may be made to the 5 embodiments described and illustrated without departing from the present invention. 1110583_1

Claims

1. A contraction joint member, including: a substantially vertical, planar body; at least two, vertically spaced, substantially horizontal, 5 flanges extending from one side of the body; and a plurality of sets of aligned holes in the flanges operable to receive supporting stakes or pins; wherein: the body and the flanges are formed from sheet metal, roll formed or folded to shape, each of the flanges being connected to an io upper or lower edge of the body by a respective connecting portion lying adjacent a side face of the one side of the body; and the body is non-compressible to accommodate thermal contraction of concrete slabs when separated by the body.

2. A joint member as claimed in Claim 1 wherein: is releasable locking means are provided between the body and/or the flanges, and the stakes or pins, to enable a vertical position of the joint member, relative to an adjacent slab to be poured, to be vertically adjusted.

3. A joint member as claimed in Claim 2, wherein: 20 a plurality of holes are provided through the body, to allow reinforcing rods and/or dowels to extend therethrough, the holes being vertically aligned with the centre line of the body.

4. A joint member as claimed in any one of Claims 1 to 3, wherein: 25 the flanges are equally spaced about the centre line of the body; and a plurality of holes are provided through the body, to allow reinforcing rods and/or dowels to extend therethrough, the holes being aligned with the centre line of the combined body and moulding strip. 30

5. A formwork for concrete slabs employing the contraction joint member as claimed in any one of Claims 1 to 4.

6. A formwork as claimed in Claim 5 wherein: 1110583_1 9 spaced holes or knock-outs are provided in the body of the expansion joint member, to allow steel reinforcing rods and/or dowel members, used to keep slabs in vertical alignment, to extend through the body. 1110583_1