NZ752040A - Extruded concrete formwork system and method - Google Patents

Abstract

A formwork system comprises an elongate form member with a front face and a rear face, the rear face being provided with a pair of longitudinally extending rails defining a channel there between, and a fixation member having a body with an aperture there through defining an axis, the body being connected to an engagement structure including a pair of flanges. The fixation member is engageable with the form member by generally aligning the aperture axis with the longitudinal extent of the form member, inserting the engagement structure within the channel, and rotating the fixation member relative to the form member so that the aperture axis is transverse to the longitudinal extent of the form member and the flanges engage with portions of the respective rails. The elongate form member may be fabricated by extrusion using a polymer material incorporating a colouring agent to produce a high-visibility yellow product. ected to an engagement structure including a pair of flanges. The fixation member is engageable with the form member by generally aligning the aperture axis with the longitudinal extent of the form member, inserting the engagement structure within the channel, and rotating the fixation member relative to the form member so that the aperture axis is transverse to the longitudinal extent of the form member and the flanges engage with portions of the respective rails. The elongate form member may be fabricated by extrusion using a polymer material incorporating a colouring agent to produce a high-visibility yellow product.

Description

EXTRUDED CONCRETE FORMWORK SYSTEM AND METHOD FIELD The invention relates generally to molding forms and, more particularly, to an apparatus and system for constructing a molding form ("formwork") used for establishing a border for forming a molded structure.

BACKGROUND Concrete pathways, decks, foundation pads and the like are commonly formed in molds constructed in-situ directly on the surface of the ground. Molding forms are placed to define the concrete border by confining the uncured concrete mixture to a desired border contour. A concrete mixture is poured over the prepared bed to fill the form and the top surface of the poured concrete smoothed and levelled. After the concrete cures to a hardened state, the forms are dismantled.

Traditionally, molding form structures that have been used in constructing concrete decks and the like have comprised timber form boards and stakes fastened together by nails. The timber form structures are constructed by driving stakes into the ground at intervals along a stake line that follows the desired edge contour of the deck. Then, the timber form boards are placed against the stakes and fastened thereto by nailing. In many cases, the stakes are displaced by the force of nailing, making it difficult to accurately locate the reference surface of the board at the reference line for the border of the deck. In addition to not being able to locate the reference surface precisely, the manner of construction of such wood form structures causes rapid deterioration of the materials used. Repeated nailing weakens the timber form boards and they may be prone to breakage during the assembling and dismantling of the forms.

SUMMARY Embodiments of the present invention are designed to take the place of traditional timber concrete formwork and provide a number of advantages.

In accordance with the present invention there is provided a form member for use in constructing formwork for molding a concrete structure, the form member comprising an elongate beam of constant cross-section, the beam structure comprising parallel upper and lower walls between which extends a front wall with a flat barrier face and a rear wall with a support face, the beam structure having a hollow interior with at least one reinforcing rib extending between the front and rear walls, wherein the elongate beam is fabricated by extrusion using a polymer material incorporating a colouring agent to produce a high-visibility yellow product.

In a preferred embodiment the support face of the rear wall includes first and second rails defining a channel therebetween for engaging with a fixation member, in use.

The elongate beam is preferably extruded from a polyvinyl chloride composition comprising, substantially, 75% PVC, 12% filler, 8% impact modifier and 5% stabiliser pack.

In accordance with the present invention there is also provided a formwork system comprising: an elongate form member with a front face and a rear face, the rear face being provided with a pair of longitudinally extending rails defining a channel therebetween; and a fixation member having a body with an aperture therethrough defining an axis, the body being connected to an engagement structure including a pair of flanges, wherein the fixation member is engageable with the form member by generally aligning the aperture axis with the longitudinal extent of the form member, inserting the engagement structure within the channel, and rotating the fixation member relative to the form member so that the aperture axis is transverse to the longitudinal extent of the form member and the flanges engage with portions of the respective rails.

The system may further include a fixation spike adapted for insertion through the fixation member aperture while the fixation member is engaged with the form member.

The system may further include a brace member including an elongate body with an engagement structure at one end for engagement with a form member, the elongate body having longitudinally extending rails defining a channel therebetween to allow selective engagement with one or more fixation members.

The forms may be made in several different sizes to suit different concrete depths for various applications.

In another aspect, a tool is provided to assist in constructing formwork for molding a concrete structure with a predetermined width and fall. The tool comprises an elongate body with stop edges spaced apart be a predetermined distance against which forms can in use be placed to establish a fixed width spacing. The tool further comprises a fall adjustment screw adjacent one of the stop edges, and a spirit level.

There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.

Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Further disclosure, objects, advantages and aspects of the present invention may be better understood by those skilled in the relevant art by reference to the following description of preferred embodiments taken in conjunction with the accompanying drawings, which are given by way of illustration only and thus not limitative of the present invention, and in which: Figure 1 is a perspective view illustrating the separate primary components of a formwork system according to an embodiment of the invention, comprising a form member, a locator device and a spike; Figure 2 is a perspective view illustrating the formwork system primary components in assembled configuration; Figures 3 and 4 are end and side views, respectively, of the assembled formwork system components from Figure 2; Figure 5 is a perspective view of the formwork system according to an embodiment of the present invention arranged for use in constructing a concrete pad; Figure 6 is a rear perspective view of a locator device according to an embodiment of the invention; Figure 7 is a front perspective view of the locator device; Figures 8 and 9 are top and side views of the locator device, respectively; Figure 10 is a perspective view showing a locator device assembled with a form member; Figures 11 and 12 show a vertical section through the locator device and form assembly of Figure 10 in perspective and end views, respectively; Figure 13 is an end view illustrating a locator device oriented for assembly with a form member; Figures 14, 15 and 16 are perspective views illustrating the steps of assembly of a locator device with a form member according to embodiments of the present invention; Figures 17 and 18 are end views of a form member and locator device with the locator device in respective first and second orientations; Figures 19, 20 and 21 are perspective views illustrating the use of a locator device to couple two form members together longitudinally; Figures 22, 23 and 24 are perspective views illustrating the use of locator devices to couple two form members together vertically; Figure 25 illustrates a tool suitable for arranging formwork to mold a concrete structure with a predetermined width and fall; and Figures 26 and 27 are perspective views of brace members for use in withstanding larger concrete pour pressures on forms.

DETAILED DESCRIPTION In the following description, where directionally related terms are used such as 'top', 'bottom', 'above', 'below', 'sides' and the like, these terms are applicable to the embodiments shown and described in conjunction with the drawings. These terms are merely used for the purpose of description in connection with the drawings and do not necessarily apply to the position in which the concrete formwork system and/or components as they may be used in a particular practice.

Embodiments of the present invention as illustrated in the accompanying drawings provide a formwork system (10) for constructing concrete molds. The system primarily comprises three components, wherein a plurality of the components are arranged and configured to construct a given formwork mold ('form') to contain the fluid concrete when poured. The three primary components are: an elongate form member 100; a locator device 200; and a securing spike 300.

The form member 100 in the preferred embodiment is an elongate member with a generally rectangular external profile. The form member 100 has parallel elongate 'top'/'bottom' walls 105 that are separated from one another by a distance defining the height of the form member. An elongate 'front' wall 104 extends between the top/bottom walls 105 on one side of the form member, and has a substantially smooth outer surface that, in use, faces inwardly in a formwork mold and is the barrier surface against which the concrete abuts. On the other side of the form member is a 'rear' wall 102 that, in use, faces outwardly of the formwork mold when constructed.

The interior of the form member 100 is substantially hollow so as to be relatively light-weight, although may include internal reinforcing ribs as described hereinbelow. The form member may be of any desired length between ends 110 and 112, and may in practice be supplied in a series of standard lengths, for example. Moreover, the form members may be readily cut to custom length on site.

The form member is preferably made from a polymer material using an extrusion manufacturing process. The polymer material is preferably a durable material that can withstand the rigours of a construction environment without undue breakage in use. The form member 100 could alternatively be made from aluminium, for example, although a polymer may generally be preferred for lower material and manufacturing costs, and also the ability to recover from being bent during use.

Through trial and experimentation, a polyvinyl chloride plastic composition has been developed to provide optimum performance in the present application for use particularly in manufacturing the extrusion moulded form members. The composition comprises 75% PVC, 12% filler, 8% impact modifier and 5% stabiliser pack. It is preferred that the polymer material used for the form members includes a colouring agent such as a pigment whereby the resulting extruded product displays a high-visibility ‘safety yellow’ colour. This provides an enhanced safety features as compared to traditional timber form boards, reducing tripping hazards and the like.

The hexadecimal RGB code of the ‘Safety Yellow’ colour is #EED202 and various pigmentation additives may be employed to achieve at least a substantially similar product colour result as will be understood by those skilled in the art of polymer compounding.

The rear side of the form member has features (described in detail hereinbelow) that allow the form member 100 to interface with a locator device 200. In particular, the rear wall 102 of the form member 100 is bounded at the top and bottom by elongate rails 120 that are spaced from the rear wall 102 and project toward one another along the length of the form member. The rails 120 define respective elongate slots 124 between each rail 120 and the rear wall 102, and a shallow channel 125 therebetween. As described further below, the rails 120 are configured to enable engagement with flanges of the locator device 200 in a manner that allows the locator device to be easily positioned anywhere along the length of the form member. When the locator device is engaged and suitably positioned, it can then be secured in place using a spike 300 to thereby hold the form member in place.

An example of a formwork structure utilising the components of the system 10 is illustrated in Figure 5. The formwork structure is arranged on a ground surface 400 to define a concrete mold region 410 into which fluid concrete will be poured. The mold region 410 is bounded by the upright front faces 104 of a plurality of form members 100. Each form member 100 has a plurality of locator devices engaged at selected positions along the rear side thereof, and each locator device 200 is in turn secured in place by a respective spike 300 driven into the ground through an axial bore in the locator device. Since the locator devices are easily repositionable along the length of the form members, the positions at which the spikes are driven into the ground can be selected to avoid rocks, pipes or other underground obstacles if necessary.

Referring specifically to Figures 6 to 9, a locator device 200 according to a preferred embodiment of the invention is shown in isolation. The locator device 200 has a flat, generally rectangular plate 204. Attached to one side of the plate 204 is a body 202 that has a cylindrical through-bore 201. The axis of the bore 201 is parallel with the longer dimension of the rectangular plate 204. The diameter of the bore 201 is dimensioned to allow the shaft 302 of a spike 300 to pass therethrough. A boss 220 extends from the middle of the body 202, projecting away from the plate 204. The boss 220 has a threaded hole 221 that is orthogonal to the axis of the bore 201 and extends through the boss 220 to the bore 201. The hole 221 is adapted to accept a locking screw (not shown) that can, in use, be screwed into the hole to impinge upon the shaft of a spike 300 within the bore 201 and thereby lock the locator device to the shaft of the spike.

On the opposite side of the plate 204 with respect to the body 202 the locator device is provided with an engagement structure. The engagement structure comprises a generally rectangular engagement member 208 that is centrally attached to the plate 204 by way of a bridge 207. The bridge 207 is lesser in extent in the dimension parallel to the axis of the bore 201, which results in two flanges 206 separated from the surface of the plate 204 by respective gaps 205. The profile of the bridge 207 is rounded, as seen at 209, as are the corners of the flanges 206, as seen at 211.

Figures 10 to 12 show the way in which the locator device 200 engages with the form member 100, in use. When in the engaged configuration the engagement member 208 of the locator device sits within the channel 125 at the rear of the form member 100, and the axis of the bore 201 is vertical (i.e. transverse to the longitudinal extent of the form member). The locator device 200 is held in place by the flanges 206 which reside in respective slots 124, and the rails 120 which reside in respective gaps 205. The engagement between the locator device 200 and form member 100 does permit displacement of the locator device along the length of the form member for selective positioning, in use.

Figures 13 to 18 best illustrate how the locator device 200 may be brought into engagement with the form member 100. Figures 13 and 14 show the locator device 200 separated from the form member 100 and oriented such that the axis of the bore 201 is parallel with the length of the form member. As is apparent particularly in Figure 13, when the locator device is so oriented the 'width' W across the engagement member 208 is less than the internal separation S between the rails 120 of the form member. This allows the locator device 200 to be manoeuvred (by movement in the direction indicated by arrow A) to place the engagement member within the channel 125 between the rails 120, such that the surface of the engagement member 208 abuts against the surface of the rear wall 102 (as seen in Figures 15 and 17). In order to engage the locator device with the form member, the locator device 200 may then be rotated by 90-degrees (generally about the axis of the hole 221) into the configuration as seen in Figures 16 and 18, for example. In doing so, the flanges 206 are rotated into the respective slots 124 with the top and bottom portions of the plate 204 on the other side of the rails 120. The rails 120 then also reside within the respective gaps 205 of the locator device, as previously described.

Disengagement of the locator device 200 from the form member 100 is accomplished by action in reverse as for the engagement procedure. Specifically, to disengage the locator device 200 is first rotated with respect to the form member 100 by 90-degrees, until the axis of the bore 201 is generally parallel with the longitudinal extent of the form member 100. The locator device can then be separated from the form member.

Referring again to the assembled system shown in Figure 5, it will be appreciated that once a locator device 200 is engaged with a form member 100 and a spike 300 is inserted through the bore 201 and driven into the ground, the locator device 200 can no longer be rotated and therefore cannot be caused to disengage from the form member 100 as described above. Only by removing the spike 300 from the ground can the locator device 200 then be rotated to an orientation for disengagement.

Figures 19 to 21 illustrate the manner in which a locator device 200 can be employed to temporarily join two form members 100 together, end-to-end. In some applications of the system the length of the formwork along a given side will exceed the available length of form member 100, requiring two or more forms to be joined end-to-end for the purpose of the task. Using the system as disclosed herein, a single locator device can be used, positioned straddling the joint 150 between two form members 100A and 100B, as seen in Figure 21. The plate 204 and engagement member 208 of the locator device has sufficient width to engage the rails 120A and 120B of the two form members 100A, 100B both at the same time while the ends abut at the join 150. The locator device 200 can be configured to engage the two form members, once aligned in place, as previously described, or the locator device can be engaged with one or other of the form members and then slid into place across the join.

Referring to Figures 22 to 24, in some applications it may be desirable for two or more form members (100C, 100D) to be used, one on top of the other. In such circumstances two locator devices (200C, 200D) may be engaged with the respective form members and positioned with their bores vertically aligned with one another. This then allows a single spike 300 to be inserted through both locator devices and driven into the ground, maintaining the two locator devices and forms in alignment. This allows for quick and convenient alignment of the form front wall surfaces 104C, 104D.

In the Figure 5 drawing, several of the spikes 300 are shown still projecting up before being fully driven into the ground. When the formwork structure is complete the tops of the spikes 300 are preferably all below the top surfaces of the form members 100, which allows the form top surfaces to be used as a guide for a screed board or the like for levelling and smoothing of the concrete within the form.

The formwork system 10 as described above is particularly suited to forming sidewalks, footpaths and the like. Specifically, the form 100 may have a height of, say, 90mm which corresponds generally to the desired concrete thickness for such application. When forming a path, for example, it is desirable for the top surface of the finished concrete to have a certain slope or "fall" from one side of the path to the other. This may be achieved by setting the forms on one side of the concrete mold at a slightly lower level than on the other side, so that when the concrete is smoothed to the top of the forms, the top surface slope is established. A tool 600 that can assist in setting up the formwork in that manner is shown in Figure 25. The tool 600 comprises a straight elongate member 602 having a length of, say, 1.7m – being slightly longer than the width of path to be formed. Near each end of the elongate member 602 the tool has respective square-edge stops 604, 608 that define outer edges 606, 610 spaced apart by a predetermined distance. The spacing between the edges 606, 610 corresponds to the desired with of the path to be formed, and serves as a guide for placement of the forms on either side of the concrete mold. The stop 608 may be adjustable so as to enable it to be placed in several different locations (612), depending on the actual desired width of the path. For example, the tool may allow adjustment of the stop 608 for placement between 1500mm and 1000mm from the opposite stop 604, in 100mm increments. At one end of the tool 600, between the stop edge 606 and the end of the elongate member 602, a fall adjustment screw 620 is provided. The fall adjustment screw has an end 622 that protrudes by an adjustable distance from the elongate member 602 adjacent the stop edge 606. In the centre of the elongate member 602 the tool 600 includes a spirit level 630.

The amount by which the screw end 622 protrudes can serve to determine the fall of the concrete path to be formed. In use, the spacing between the stop edges 606, 610 of the tool 600 can be used to establish a desired set distance between forms 100 which are then fixed in place using the locator devices 200 and spikes 300 as described above. Then with the tool 600 lying across the mold structure, the forms on one side may be raised slightly to obtain a level reading on the spirit level 630. Depending on the setting of the fall adjustment screw, this establishes the forms on one side with a level higher by a corresponding amount. The forms can then be fixed at that level by setting locking screws in the holes 221 of the locator devices 200.

In the system as described above, the forms 100, locator devices 200 and spikes 300 are sufficient to create a formwork structure suitable for molding a concrete path or the like, having relatively thin concrete. Other types of concrete formations, such as foundation slabs for example, may require higher forms in order to mold thicker poured concrete. As described above shown in Figures 22-24, it is possible to stack one form on top of another to create a deeper mold structure. Alternatively, it is also possible to manufacture taller forms for that purpose, having a similar structure to the form 100 previously described, but with a greater height. For example, where the form 100 may have a height of 90mm, other forms may be manufactured with heights of 170mm and 240mm, for example. When using a higher concrete mold, an additional consideration to take into account is that the thicker poured concrete exerts significantly more pressure on the forms, and the spikes holding them in place. Accordingly, to ensure the forms remain fixed in place while the concrete cures, brace members may be used in place of or in addition to the locator devices and spikes. For example, a brace member 500 according to an embodiment of the invention is shown in Figure 26. The brace member 500 has an elongate body 502 that may be formed from a length of extrusion of similar construction to the forms 100, having a channel 512 along one side adapted to receive and engage with locator devices 200. At one end of the elongate body 502 the brace member 500 has a transverse plate 504 and engagement member 508 constructed in similar fashion to the plate 204 and engagement member 208 of a locator device 200 as previously described. In the case of the brace member 500 seen in Figure 26, the engagement member 508 is enlarged for engagement with a taller form, for example of 170mm height. An alternative brace member 550 is shown in Figure 27. For example, a brace member 550 having a length of approximately one metre may be provided for use with a 240mm height slab form.

In use, the brace member 500 is engaged with a form at a desired location and then fixed into place using spikes through one or more locator devices 200. Since the locator devices on the brace member 200 can be spaced further from the form by virtue of the elongate body 502, higher pressure on the form from a thicker concrete pour can be withstood.

The structure and implementation of embodiments of the invention has been described by way of non-limiting example only, and many additional modifications and variations may be apparent to those skilled in the relevant art without departing from the spirit and scope of the invention described.

Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material forms part of the prior art base or common general knowledge in the relevant art in Australia or elsewhere on or before the priority date of the disclosure and claims herein.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (8)

1. A formwork system comprising: an elongate form member with a front face and a rear face, the rear face being provided 5 with a pair of longitudinally extending rails defining a channel therebetween; and a fixation member having a body with an aperture therethrough defining an axis, the body being connected to an engagement structure including a pair of flanges, wherein the fixation member is engageable with the form member by generally aligning the aperture axis with the longitudinal extent of the form member, inserting the engagement structure within the channel, 10 and rotating the fixation member relative to the form member so that the aperture axis is transverse to the longitudinal extent of the form member and the flanges engage with portions of the respective rails.

2. A system according to claim 1 further including a fixation spike adapted for insertion 15 through the fixation member aperture while the fixation member is engaged with the form member.

3. A system according to claim 1 or 2 further including a brace member including an elongate body with an engagement structure at one end for engagement with a form member, the 20 elongate body having longitudinally extending rails defining a channel therebetween to allow selective engagement with one or more fixation members.

4. A form member for use in constructing formwork for molding a concrete structure, the form member comprising an elongate beam of constant cross-section, the beam structure 25 comprising parallel upper and lower walls between which extends a front wall with a flat barrier face and a rear wall with a support face, the beam structure having a hollow interior with at least one reinforcing rib extending between the front and rear walls, wherein the elongate beam is fabricated by extrusion using a polymer material incorporating a colouring agent to produce a high-visibility yellow product.

5. A form member according to claim 4, wherein the support face of the rear wall includes first and second rails defining a channel therebetween for engaging with a fixation member, in use. 5

6. A form member according to claim 4 or 5, wherein the elongate beam is extruded from a polyvinyl chloride composition.

7. A form member according to claim 6, wherein the composition comprises, substantially, 75% PVC, 12% filler, 8% impact modifier and 5% stabiliser pack.

8. A tool to assist in constructing formwork for molding a concrete structure with a predetermined width and fall, the tool comprising an elongate body with stop edges spaced apart by a predetermined distance against which forms can in use be placed to establish a fixed width spacing, the tool further comprising a fall adjustment screw adjacent one of the stop edges, and a 15 spirit level.