GB2026072A - Formwork panel - Google Patents

Abstract

A formwork panel is formed from a plastics material, and has spaced apart plane shins 1, 2 separated by a lattice-work of internal walls to form a plurality of cells or compartments which are packed with a filler, such as expanded polystyrene. The rear shin 2 is omitted from some cells to provide access to bolt holes 8 in the panel's sides. <IMAGE>

Description

SPECIFICATION Formwork for concrete The present invention concerns formwork for concrete.

In the context of the present invention the term "formwork" denotes boarding, sheeting, shuttering or the like which is erected to contain wet concrete during placing and hardening. The face texture of the formwork together with its rigidity or stiffness determine the appearance of the concrete when set and it is important to achieve a good surface appearance in order, for example, that a decorative finish can be applied directly to the concrete surface.

At present, formwork for concrete is assembled from panels which are mounted on battens or the like supports. Plywood panels are common although it is known to use panels of other materials such as steel sheets. A disadvantage of plywood panels is that they are not robust and cannot stand rough handling. Further such panels rapidly deteriorate when left out in open in all weathers. Steel panels on the other hand are relatively expensive and can be awkward to handle on account of the weight.

The aim of the invention is to provide an improved panel for use in formwork for concrete.

According to one aspect of the present invention there is provided a rigid panel for use in formwork for concrete, the panel comprising an integral sandwich of plastics material having first and second sheet surfaces with the space between the sheet surface divided into a plurality of closed cells or compartments, each cell or compartment being packed with a filler material, openings being arranged at spaced intervals and extending through the thickness of the panel to receive tie-rods or the like and further openings at predetermined positions in the peripheral edge wall of the panel to receive bolts to enable panels to be secured together in abutting edge-to-edge relationship to form the formwork, the bolt openings being accessible through one of the sheet surfaces.

According to another aspect of the present invention there is provided formwork for concrete comprising a plurality of double skin panels formed from a plastics material and having a plurality of compartments packed with a filler material and means for releasably securing together the panels in edge-to-edge abutting relationship.

According to yet another aspect of the present invention there is provided a method of assemblying formwork from a plurality of individual panels of the kind hereinbefore defined.

The invention will be described further, by way of example, with reference to the accompanying drawings; in which: Figure 1 is a sectional plan view of a panel on the line I-I in Fig. 2; Figure 2 is a section of the panel on the line Il-Il in Fig. 1.

Figure 3 is a reverse plan view of the panel; and Figure 4 is a section on line IV-IV in Fig. 3.

With reference to the drawings, a panel constructed according to the invention comprises an integral cellular assembly formed from a plastics material, a suitable plastics material being high density polyethylene. The panel is formed as an integral double-skin unit divided internally into a plurality of individual compartments. Thus the panel comprises first and second surface skins 1 and 2 respectively, an outer peripheral wall 3 and a latticework of internal walls 4 disposed at right angles to one another to define the internal compartments 5. The panel can be manufactured by existing techniques known in the plastics industry. A plurality of apertures 6 are provided at predetermined positions and extend through the thickness of the panel. The purpose of these apertures 6 will be explained hereinafter.The first surface skin 1 which is the surface adapted to be in contact with the concrete will be termed the working surface and the second surface skin 2 will be termed the other surface of the panel.

The illustrated panel can be 1 metre square with a thickness of 100 mm. although it will be realised that such dimensions are by way of example only and in no way are to be construed as limitations on the geometrical dimensions of the panels.

In practice a plurality of panels will be joined together to provide a required formwork and with reference to Figs. 3 and 4 it will be observed that pairs of compartments 7 adjacent each corner of the panel are left open to provide access to a hole 8 formed in the outer edge wall of each compartment 7.

In this way formwork can be constructed by bringing a plurality of panels into edge-toedge abutting relationship and securing adjacent panels together by bolting through the holes 8.

In use and, for example, to form a concrete wall the formwork formed from the panels is erected and positioned in place to receive the concrete. To form a wall, two formwork assemblies are required to contain the concrete whilst setting and hardening, the assemblies being spaced apart by a distance determined by the thickness of the wall. Upon erecting and positioning the formwork tie bars, for example steel rods, can be passed through the apertures 6 in opposing panels. Conveniently, each tie bar can be formed in three parts namely a centre part and two end parts which can be releasably connected together for example by screw thread connections. The end parts extend through the apertures 6 in the opposing panels of the assembled formwork with the centre part disposed in the gap to receive the concrete.The assembled formwork will be supported and reinforced by joists and the like bearing against the other surfaces 2 as in case of conventional shuttering. Concrete is then poured between the spaced apart formwork and allowed to set therebetween.

Thereafter, the formwork can be dismantled by removing the supporting joists, releasing the tie bars by disengaging the end parts from the centre part of each and removing the individual panels by disengaging the bolts passing through the holes 8. The surfaces provided by the skins of the panels ensure a good smooth clean finish to the concrete and no irregularities or steps appear between adjacent panels which could mar the surface finish of the concrete. The recesses or cavities left in the concrete upon withdrawing the end parts of the tie bars can be filled in by hand.

The closed compartments 5 of the panels are preferably packed during manufacture of the panels with a filler material, e.g. expanded polystyrene. This filler or packing serves to strengthen the panel without significantly increasing the weight of the panel and also serves as a grip medium to enable formers or shaping pieces to be releasably attached to the working face 1 of the panel, that is the face to contact the concrete. For example, it might be required to form recesses or cavities in a face of the wall. These can be provided by securing formers of the required shape and dimensions to the face 1 of the panel. The formers can be positioned by nailing or otherwise securing in position, the nails being releasably gripped by the filling or packing within the compartments 5.In a similar manner members can be secured to the other face 2 of each panel to cooperate with and locate the support joists in position.

Removable filler plugs can be provided for the apertures 6 when it is not required to insert tie bars therethrough. The plugs are such that when inserted in the apertures they ensure a smooth uninterrupted surface with the surface of the panel.

As an additional means for locating panels in abutting edge-to-edge relationship, the peripheral walls of the panels can be formed with cooperating keyways. For example a tongue on an end wall of a first panel can cooperate with a corresponding groove on the end wall of a second panel. Such an arrangement assists in locating the panels against lateral displacements.

It will be appreciated that the invention is not confined to the panel construction shown in the drawings. Other shapes and geometries are possible and it is not necessary to restrict the invention to square panels having internal square compartments.

Claims (10)

1. A rigid panel for use in formwork for concrete, the panel comprising an integral sandwich of plastics material having first and second sheet surfaces with the space between the sheet surfaces divided into a plurality of cells or compartments, each cell or compartment being packed with a filler material, openings being arranged at spaced intervals and extending through the thickness of the panel to receive tie-rods or the like and further openings at predetermined positions in a peripheral edge wall of the panel to receive bolts or the like to enable panels to be secured together in abutting edge-to-edge relationship to form the formwork, the further openings being accessible through one of the sheet surfaces.

2. A panel as claimed in claim 1 including removable filler plugs for insertion in said openings extending through the thickness of the panel, each plug being such that when inserted an end thereof provides a smooth uninterrupted surface with the corresponding surface of the panel.

3. A panel as claimed in claim 1 or 2 including keying means in the peripheral edge wall to locate adjacent panels against lateral displacements.

4. A panel as claimed in any preceding claim in which the filler material is expanded polystyrene.

5. A panel as claimed in any preceding claim including formers releasably attachable to the surfaces of the panel.

6. Formwork for concrete when formed from a plurality of panels as claimed in any preceding claim and means for releasably securing the panels together in edge-to-edge abutting relationship.

7. Formwork for concrete as claimed in claim 6, in which the releasable securing means comprises bolts or the like extending through aligned openings in peripheral edge walls of adjacent panels.

8. Formwork for concrete as claimed in claim 6 or 7 comprising first and second assemblies of panels spaced apart at a predetermined distance and releasably secured together by tie bars on the like passing through said openings in the panels.

9. A rigid panel for use in formwork for concrete substantially as herein described with reference to and as illustrated in the accompanying drawings.

10. Formwork for concrete when formed from a plurality of panels as claimed in claim 9.