Patent Application
20120102862
THIS INVENTION relates to improvements in and in relation to edging and metal edging for concrete slabs and in particular but not limited to metal edging of the type employing an upper flange in a concrete joint to protect the upper corner edge of a slab to which the edging is fixed and to an improved nailing bracket for this type of edging.
Applicant has for the first time recognised problems that were not previously recognised in relation to concrete joints employing edging of the type using prefabricated parallel metal strips or bars to form the joint. The strips or bars are held together for transport and installation purposes using some kind of frangible connection so that when in-situ the strips or bars, as the case may be, can separate as the concrete contracts. In this way the strips remains in intimate protective engagement with the concrete so that each strip serves to protect the adjacent edge of the concrete at the joint.
Applicant's specification is directed to a number of improvements and these are set out below both independently and in combination. Applicant reserves the right to divide the application and/or claim the improvements in combination subject to the outcome of any official search and examination.
In the present specification a reference to “metal” is non-limiting as other material may be used but generally these materials will be effective in protecting the edge of the concrete and could include particular plastics or other materials that might be sufficiently robust.
In one broad form of the invention there is provided an improvement in metal edging for concrete slabs, the edging comprising first and second edging strips running parallel to one another, the first edging strip having a longitudinally extending web and an upper flange, the second edging strip having a longitudinally extending web and an upper flange mating the flange of the first edging strip, the strips being set in back to back relationship with upper flanges of the strips being in alignment and extending in opposite transverse directions, a fixing plates extending from one of said strips, the fixing plate being adapted to secure the edging to formwork located below the edging, the fixing plate having a horizontal slide plate overlapping and slidable across a lower edge of one of said strips and the fixing plate having a vertical plate adapted to fix the vertical plate to the formwork.
Typically, plural spaced fixing plates are employed and each fixing plate comprises a nailing bracket having plates at 90 degrees, the vertical plate having spaced holes to receive fasteners, at least one of said strips having a lower horizontal flange with an edge and the flange being adapted to locate the edging on top of formwork of rectangular section with the flange being on top of the formwork and the vertical plate forming a right angle with the flange, with the vertical plate being securable to a vertical side of the formwork in offset relation from the edge of the flange.
In a preferred form the vertical plate has spaced holes to receive fasteners, the fixing plate comprising an elongate horizontal section of the plate having projecting lobes at each end, secured to an underside of one of the strips with the other strip located on top of the elongate horizontal section, the elongate section having tapered corners opposite each lobe and the vertical plate extending in a plane located between the lobes.
In another aspect there is provided an improvement in metal edging for concrete slabs, the edging comprising a first edging strip having a longitudinally extending web and preferably an upper flange and a second edging strip having a longitudinally extending web and preferably also an upper flange mating the flange of the other strip, the strips being set in back to back relationship with upper edges of the strips being in alignment and extending in opposite transverse directions, spaced vertical fixing means extending from the strips and being rigid with one of said strips, the fixing means being adapted to secure the edging to formwork located below the edging, the form being secured using spaced nailing brackets having plates at 90 degrees, the plates having spaced holes to receive fasteners.
In another aspect there is provided an improvement in metal edging in a form work assembly comprising metal edging as described in the preceding paragraph, the edging having a lower horizontal flange adapted to locate the edging on top of a form with the fixing means preferably comprising a plate secured to the side of the form in offset relation. In this case the lower flange and the plate are typically set at 90 degrees and a nail or screw or other fitting is driven or screwed through the fixing plates into the form. The form may be timber and below the edging in use dowel sleeves may be secured to the timber form. After one slab is poured the timber form is stripped away leaving the metal edging in place and then another slap is poured. When the slabs contract the strips separate with the slabs. It is preferable to have each strip equipped with projecting bolts or other suitable transverse projecting means that project into the slabs to aid retention of the strips and prevent separation of the strips from the concrete.
Typically, the edging strips are held together by frangible fasteners. Typically the frangible fasteners comprise spaced apart rivets with plastics washers so the rivets pass through the edging strips and are expanded within the washers so that the rivets shear off when the concrete contacts and the strips separate.
In another improvement, there is provided edging for concrete at a joint, the edging comprising back-to-back edging strips adapted as lost formwork in concrete and being adapted to separate upon contraction of the concrete to form a gap between the strips, each edging strip having an upper edge, a bridging member extending across the strips and being secured to at least one of the edging strips so that upon separation of the edging strips in-situ, the bridging member extends at least part way across the gap below the upper edge. Typically, the bridging member slides underneath the other edging strip. Preferably the bridging member is plate welded or otherwise secured to an underside of one of the strips so that it projects under the other strip.
In one preferred embodiment the bridging member is a trapezium shaped plate. Preferably the bridging member is one of a plurality of spaced bridging members located along the length of the strips.
In a preferred aspect, a gap between strips in a concrete metal edging comprising separable strips is fillable by a filling strip insertable in the gap after the strips have separated, the gap so formed having a bottom and a top, the top being adjacent an upper edge of the edging, the edging having a filling strip support located in the gap at so that the filling strip is located substantially contiguous with the upper edge of the edging when located in the gap and supported by the support. Typically the support is a bridging member as described above. The filling strip may be a mastic paste or a preformed strip in metal or hard plastics or any suitable filler may be employed.
In order that the present improvements may be more readily understood and put into practical effect reference will now be made to the accompanying drawings which illustrate preferred embodiments of the invention and wherein:—
Referring to the drawings and initially to
The edging strips 11 and 12 have lower flanges 19 and 20 and respective webs 21 and 22 which are in abutment so the strips are in back to back relation with the flanges 11, 12, 19 and 20 extending transversely in opposite directions.
Spaced headed rods 23 and 24 on opposite sides serve to retain the edging strips 11 and 12 in place and vertical fixing plates 25 are welded at spaced intervals to the strip 11 with each plate 25 have a pair of spaced nail holes so that the edging may be nailed to a timber form being plank 26. Dowel sleeves 27 are also nailed to the timber form.
Strips 11 and 12 and the headed rods 23 and 24 and the dowel sleeves 27 are lost in the concrete slab 15 and the timber plank 26 is stripped from the slab 15 before the slab 16 is poured. After the plank 26 is stripped dowels are inserted into the sleeves 27 before the slab 16 is poured.
It will be appreciated that in the region of contact with the form of the flange 20 and the plates 25 there is a right angle between the flange 20 and the plate 25 and this serves to easily locate and secure the strip in proper position relative to the plank 26. Of course the plank 26 ideally is selected to be straight so that the proper depth and positioning of the edging strip can be achieved. Since the first slab to be poured is the slab 15 and the flange 25 is on the same side of the timber plank 26 the tendency of either of the edging strips 11 and 12 to roll to the right in terms of
Once the slab 16 has been poured and the concrete expands and contracts, rivets 28 are designed to shear so that the plates 11 and 12 may separate. Thus the strips 11 and 12 have spaced holes 29 for the purpose of taking the rivets illustrated in
Now one improvement set out above is the implementation of a platform for a filler to go in this gap. While a single long platform could be provided it is preferable to locate short horizontal plates at spaced interval along one of the strips. In the preferred embodiment these are centred on the headed rods 23 and 24 so there is one for each rod.
The platform 32 has tapered corners 36 and 37 to aid release from the concrete.
Whilst the above has been given by way of illustrative example many variations and modifications 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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010236065 | Oct 2010 | AU | national |
| 2011902575 | Jun 2011 | AU | national |
