Connectable panels for concrete formwork

Abstract

A connectable panel for a stay-in-place modular concrete formwork system neatly stacks with other identical connectable panels. In a stack of such panels, the connecting means at either end of a particular connectable panel is protected from bending and distortion from the weight of other panels above it. Each connectable panel has a middle section and connecting means at two connecting sections at opposite ends of the panels. The sum of the widths of the two connecting sections, including their respective connecting means, is equal to or less than the width of the middle section including projections extending from the middle section. Formwork for cylindrical structures of varying diameters may be assembled with the connectable panels, connectors, and a series of identical insulation inserts.

Description

CONNECTABLE PANELS FOR CONCRETE FORMWORKFIELD OF THE INVENTION

[0001] This invention is in the field of modular formwork systems. More specifically, this invention relates to connectable panels for modular formwork systems.BACKGROUND

[0002] Connectable panels for stay-in-place modular concrete formwork systems are known. For instance, US Patent No. 11,591,794 to Piccone discloses one type of stay-in-place modular concrete formwork system that uses connectable panels.

[0003] However, with prior art connectable panels, such as those in US Patent No. 11,591,794 to Piccone, issues can arise during the storage and shipping. In particular, the structural elements that function to connect the panels may become bent or distorted, resulting in problems with assembling the formwork system and potentially rendering the panels unusable.

[0004] Other issues may also be present when using connector panels to form concrete formwork systems. For instance, in an assembled wall using connector panels, some deformation or buckling of the panels may occur. Even though this may not affect the structural integrity and performance of the wall, it can be an aesthetic concern.

[0005] Additionally, and particularly in a curved wall application, the forces at the connection between two panels may result in some degree of separation between portions of the two panels at the connection. This can also be an aesthetic concern, and depending on the structures and degree of forces, could also potentially affect the stability of the wall.SUMMARY OF THE INVENTION

[0010] The present invention is a connectable panel for a stay-in-place modular concrete formwork system that is capable of stacking neatly with identical connectable panels. In a stack of panels, the connecting means at either ends of a panel is protected from bending and distortion from the weight of other panels above it. Projections extending from a middle section of the panels are sufficiently long to create space between two adjacently stacked panels. Additionally, the connecting means at either ends of the panels are sufficiently short that the length of the connecting means at one end of the panel combined with the length of the connecting means at the opposite end of the panel is less than or equal to the length of the projections extending from the middle section of a panel.

[0011] In one embodiment, the invention is a connectable panel for a concrete formwork system. The connectable panel comprises a first connecting section, a middle section, and a second connecting section. The first connecting section has an outer surface and at least one first connecting member extending a distance Y in a first direction laterally from an opposite side of the outer surface. The middle section has a first end, a second end, an outer surface substantially aligned with the outer surface of the first connecting section, and at least one projection extending a distance X in the first direction on a side opposite to the outer surface of the middle section, the middle section connected at the first end to the first connecting section. The second connecting section is connected to the middle section at the second end of the middle section, the second connecting section having at least one second connecting member extending a distance Z in a second direction opposite to the first direction and the second connecting section connectable to the first connecting section of a same connectable panel. The sum of distances Y and Z is equal to or less than distance X.

[0012] In another aspect, the second connecting section is connected to the middle section by a bend.

[0013] In another aspect, the at least one first connecting member is a series of teeth and the at least one second connecting member is a hooking element such that the hooking element is insertable between two teeth of an identical connectable panel.

[0014] In another aspect, the at least one first connecting member is a series of teeth and the at least one second connecting member is two hooking elements such that each of the two hooking elements is insertable between two teeth of an identical connectable panel.

[0015] In another aspect, each of the teeth is T-shaped.

[0016] In another aspect, the hooking element is T-shaped.

[0017] In another aspect, the hooking element is J-shaped.

[0018] In another aspect, distance Y and distance Z are the same.

[0019] In another aspect, when the connectable panel is stacked together with a second panel identical to the connectable panel, the at least one projection of the connectable panel is adjacent to at least one projection of the second panel, the at least one first connecting member of the connectable panel is adjacent to a second connecting section of the second panel, and the second connecting section of the connectable panel is adjacent to at least one first connecting member of the second panel.

[0020] In another aspect, the outer surface of the middle section has at least one groove to divide the middle section into at least two sections.

[0021] In another embodiment, the invention is an assembly of two identical connectable panels for a concrete formwork system stacked together. Each of the identical connectable panels comprises a first connecting section, a middle section, and a second connecting section. The first connecting section has an outer surface and at least one first connecting member extending a distance Y in a first direction laterally from an opposite side of the outer surface. The middle section has a first end, a second end, an outer surface substantially aligned with the outer surface of the first connecting section, and at least one projection extending a distance X in the first direction on a side opposite to the outer surface of the middle section, the middle section connected at the first end to the first connecting section. The second connecting section is connected to the middle section at the second end of the middle section, the second connecting section having at least one second connecting member extending a distance Z in a second direction opposite to the first direction and the second connecting section connectable to the first connecting section of a same connectable panel. The sum of distances Y and Z is equal to or less than distance X. In the assembly, the at least one projection of a first panel of the two identical connectable panels is adjacent to at least one projection of a second panel of the two identical connectable panel, the at least one first connecting member of the first panel is adjacent to the second connecting section of the second panel, and the second connecting section of the first panel is adjacent to the at least one second connecting member of the first second panel.

[0022] In another aspect, the second connecting section is connected to the middle section by a bend.

[0023] In another aspect, the at least one first connecting member is a series of teeth and the at least one second connecting member is a hooking element such that the hooking element is insertable between two teeth of an identical connectable panel.

[0024] In another aspect, the at least one first connecting member is a series of teeth and the at least one second connecting member is two hooking elements such that each of the two hooking elements is insertable between two teeth of an identical connectable panel.

[0025] In another aspect, each of the teeth is T-shaped.

[0026] In another aspect, the hooking element is T-shaped.

[0027] In another aspect, the hooking element is J-shaped.

[0028] In another aspect, distance Y and distance Z are the same.

[0029] In another aspect, the outer surface of the middle section has at least one groove to divide the middle section into at least two sections.

[0030] In another embodiment, the invention is a method of constructing formwork for a curved wall. A first series of connectable panels are provided, and the first connecting section of panels in the first series are connected with the second connection section of adjacent panels in the first series at a first connection position to form an outer wall. A second series of connectable panels are provided, and the first connecting section of panels in the second series are connected with the second connection section of adjacent panels in the second series at a second connection position to form an inner wall. The second connection position is different than the first connection position. The first series of connectable panels are connected to the second series of connectable panels using connectors secured at one end to the at least one projection of panels in the first series and secured at the opposite end to the at least one projection of panels in the second series. A series of insulation inserts is provided, with each insulation having an exterior side and an interior side, the exterior side being wider than the interior side. The series ofinsulation inserts are placed between the outer wall and inner wall, with the exterior side of each insulation insert in the series of insulation inserts being placed adjacent to the outer wall.DESCRIPTION OF THE DRAWINGS

[0031] While the invention is claimed in the concluding portions hereof, example embodiments are provided in the accompanying detailed description which may be best understood in conjunction with the accompanying diagrams where like parts in each of the several diagrams are labeled with like numbers, and where:FIG. 1 is a top view of a segment of formwork for a curved wall using a series of connectable panels according to a first embodiment of the invention; FIG. 2 is a top view of a segment of formwork for a straight wall using a series of connectable panels according to the first embodiment of the invention;FIG. 3 is a top view of one of the connectable panels shown in FIG. 1 and FIG. 2;FIG. 4 is a top view of a connectable panel according to a second embodiment of the invention; FIG. 5 is a top view of a connectable panel according to a third embodiment of the invention;FIG. 6 is a side view of stack of connectable panels, all of the embodiment shown in FIG.3;FIG. 7 is a side view of a stack of two of the connectable panels shown in FIG. 6;FIG. 8 is a top view of two connectable panels, both of the embodiment shown in FIG. 3, connected together;FIG. 9 is a top view of a connectable panel according to a fourth embodiment of the invention;FIG. 10 is a top view of a series of connectable panels, all of the embodiment shown in FIG. 9, showing differing connection locations between adjacent panels;FIG. 11 is a top view of a segment of formwork for a wall showing the connection between two connectable panels with a single ridge for connecting with an adjacent panel;FIG. 12 is a top view of a segment of formwork for a wall showing the connection between two connectable panels, both of the embodiment shown in FIG. 9; andFIG. 13 is a top view of a segment of form work for a curved wall using a series of connectable panels, all of the embodiment shown in FIG. 9, and with insulation.DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0032] Illustrative embodiments of the invention are described below. The following explanation provides specific details for a thorough understanding of and enabling description for these embodiments. One skilled in the art will understand that the invention may be practiced without such details. In other instances, well-known structures and functions have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0033] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." Words using the singular or plural number also include the plural or singular number respectively. Additionally, the words "herein," "above," "below" and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. When the claims use the word "or" in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list and any combination of the items in the list. When the word "each" is used to refer to an element that was previously introduced as being at least one in number, the word "each" does not necessarily imply a plurality of the elements, but can also mean a singular element.

[0034] FIG. 1 illustrates form work 2 for a curved concrete wall that includes a series of connectable panels 102 assembled together with connectors 8 and diagonal connectors 10 to form an outer wall 4 and second series of connectable panels 102 assembled together to form an inner wall 6. Such a curved wall may for instance be for a cylindrical tank or container for biogas plants. A smaller number of connectable panels 102 may also be connected together to create formwork for a concrete sump, having a diameter as small as 30 inches. For instance, on a larger project the leftover connectable panels 102 may be used to build such concrete sumps.

[0035] FIG. 2 illustrates formwork 52 for a straight concrete wall that includes a series of connectable panels 102 assembled together to form a first wall 54 and second series of connectable panels 102 assembled together to form a second wall 56. One of first wall 54 andsecond wall 56 may be an inner wall and the other an outer wall. Formwork 52 may also use connectors 8 and diagonal connectors 10 between walls 54, 56.

[0036] The profile of connectable panel 102 is shown in isolation in FIG. 3. Generally, connectable panel 102 has three sections: a first connecting section 104, a middle section 106, and a second connecting section 108. The first connecting section 104 is configured to connect with the second connection section 108 of an adjacent connecting panel.

[0037] First connecting section 104 has a wall 110 having an exterior side 112 and an interior side 114. A series of teeth 116 extend laterally from the interior side 114 of the wall 110 a distance Y. The series of teeth 116 form a series of ribs as they run along the length of the panel.

[0038] The series of teeth 116 form a series of gaps 118. While connecting section 104 is shown as having four gaps 118, it will be appreciated that a different number of gaps is possible with a lower or greater number of teeth 116. The size, shape, and configuration of gaps 118 may also vary depending on the size, shape, and configuration of teeth 116.

[0039] Middle section 106 has wall 130 having an exterior side 132 and an interior side 134. A series of projecting elements 136 extend laterally from the interior side 134 of wall 130 a distance X. The projecting elements 136 may run along the length of wall 130 (extending into the page in FIG. 3). A pair of projecting elements 136 can be connected to different elements when building formwork, such as connecting elements 8 and diagonal connectors 10 (shown in FIGS 1 and 2). While wall 130 is shown as having three pairs of projecting elements 136, fewer or more projecting elements 136 may be used. Projecting elements 136 can be located at a variety of locations along wall 130.

[0040] Second connecting section 108 has a wall 150 having an exterior facing side 152 and an interior facing side 154. Bend 160 between first wall 130 of middle section 106 and wall 150 of second connecting section 108 results in wall 150 being on a different plane compared to walls 110, 130. Alternatively, if a bend were instead present between wall 110 and wall 130, then wall 130 and 150 would be on the same plane and wall 110 on a different plane. Instead of a bend 160, other structures are possible to place wall 150 (or wall 110) on a different plane than wall 130, including for example a curve.

[0041] The end of the second connecting section 108 has a ridge 156, however it will be appreciated that ridge 156 may alternatively be inwards a certain distance from the end. A person skilled the art will further appreciate that while ridge 156 is shown as being T-shaped, it may have a different shape. Second connecting section 108 also has a second ridge 158 inwardly spaced compared to ridge 156. Second ridge 158 is shown in FIG. 3 as a J-shaped hooking element with an end hooking away from the middle section 106. However, it will be appreciated that second ridge 158 may be shaped differently. For instance, second ridge 158 could be a J- shaped hooking element with an end hooking towards the middle section 106 rather than away from it. Ridges 156 and 158 extend laterally from the exterior facing side 152 of the wall 150 a distance Z. During the assembly, when two panels 102 are connected together ridge 156 is slid into one of the gaps 118 of an adjacent panel 102.

[0042] FIG. 4 shows an alternate connectable panel 202 with two T-shaped ridges, 256, 258 extending laterally from the exterior facing side 252 of second connecting section 208.

[0043] FIG. 5 shows another connectable panel 302 with a single T-shaped ridge 356 extending laterally from the exterior facing side 352 of second connecting section 308.

[0044] Referring back to FIG. 3, while first connecting section 104 has a series of teeth 116 and is connectable to second connecting section 108 having ridges 156, 158, other connecting structures are possible provided distance Y that the connecting structures extend from first connecting section 104 plus distance Z that the connecting structures extend from second connecting section 108 is no greater than distance X that the projecting elements 136 extend from middle section 106.

[0045] FIG. 6 demonstrates connectable panels 102a, 102b, 102c, 102d, 102e, 102f, 102g, 102h stacked one above the other, as may be the case during storage and shipping. The teeth and ridges of any given panel (excluding the very top and very bottom panel) are protected by walls of panels immediately below or above in a stack of panels. For example, the teeth 116d and ridges 158d, 156d of panel 102d are protected by the wall 130c and wall 150e of panels 102c and 102e immediately below and above panel 102c in the stack. As a result of the spacing created by projections 136c, 136d, weight and pressure is not exerted on teeth 116d and ridges 158d, 156d in the stack of panels, thereby preventing damages and bending to such elements.

[0046] Pairs of connectable panels, for instance connectable panels 102c, 102d shown in FIG. 7 are stacked such that exterior sides 132d, 132c of middle sections 130d, 130c respectively face outward. Additionally, projecting elements 136d extending from interior side 134d face inwards towards panel 102c and projecting elements 136c extending from interior side 134c face inwards towards panel 102d. When stacked, the end of projecting elements 136d are close to or touch interior side 134c of panel 102c and the end of projecting elements 136c are close to or touch interior side 134d of panel 102d. In such a stacked configuration, the space between walls 130d, 130c can alternate between pairs of projecting elements 136d and pairs of projecting elements136c

[0047] As shown on the left side of FIG. 7, first connecting section 104d of panel 102d is stacked over second connecting section 108c of panel 102c. The ends of teeth 116d extending from wall llOd are close to or touch the exterior facing side 154c of wall 150c of panel 102c.

[0048] As shown on the right side of FIG. 7, second connecting section 108d of panel 102d is stacked over first connecting section 104c of panel 102c. The ends of teeth 116c extending from wall 110c are close to or touch the exterior facing side 154d of wall 150d of panel 102d.

[0049] As the sum of distance Z that ridges 158d, 156d extend from wall 150d plus distance Y that teeth 116c extend from wall 110c is less than or equal to distance X that projections 136c and 136d extend from walls 130c and 130d respectively, there are no elements of second connecting section 108d and no elements of first connecting section 104d that extend beyond the planes that walls 130c and 130d lie on.

[0050] In one embodiment, teeth 116c could extend outwards from wall 110c half of the distance that projections 136c extends from wall 103c. Similarly, projections 158d, 156d could extend outwards from wall 150d half of the distance that projections 136d extend from wall 130d.

[0051] Connectable panels are connected together to form a wall for form work of the kind generally described in this application. FIG. 8 shows panel 102a connected end-to-end to panel 102b. Panel 102a has ridges 156a and 158a at second connecting section 108a and panel 102b has gaps 118a, 118b, 118c, and 118d at first connecting section 104b. Ridge 156a is shown as fitting into innermost gap 118d and ridge 158a is shown as fitting into the third innermost gap 118b. However, ridge 156a may alternatively fit into gaps 118a, 118b, or 118c. If ridge 156a is fitted into gaps 118a or 118b, it will be appreciated that ridge 158a will be outside first connecting section 104b of panel 102b and not be placed within any gap. The ability to choosewhere ridge 156a fits along first connecting section 104b permits small variations in the length of the wall which is desirable if building with a set of identical panels 102. It will be appreciated that different connecting means at second connecting section 108a and first connecting section 104b are possible.

[0052] Preferably, the different elements of the connectable panels 102 are made of a plastic material that is slightly flexible and deformable, so that when the elements of the connectable panels are under stress, such as when the interior of the formwork is filled with concrete, the panels can maintain their strength. In particular, such a type of material will allow the connection between first connecting section 104 and second connecting section 108 of adjacent panels to flex or mold slightly when under stress in order to create a seal between the connecting ends of adjacent panels. Such a seal is useful in building walls and structures that must be water-tight or fluid-tight.Oil Canning Prevention

[0053] FIG. 9 shows another connector panel 402 with a first connecting section 404, a middle section 406, and a second connecting section 408. One again, projections 436 extend sufficiently far away from wall 430 of middle section 406 and the connecting means at the first and second connecting sections, 404, 408, are sufficiently short such that the combined thickness of such connecting means is less than or equal to the depth that projections 436 are spaced apart from the interior side 434 of wall 430. This creates space between connector panel 402 stacked with an identical connector panel to prevent the damage and bending of the connecting means.

[0054] Rather than a generally planar exterior side 132 (as shown in FIG. 3), exterior side 432 of panel 402 has a series of spaced apart grooves 462. Groove 462 may be opposite projections 436,though other locations for the grooves 462 are possible. Panel 402 is shown as having five grooves 462, though the number of grooves can also be varied. For instance, the number of grooves may be one, two, etc. depending on the width of a panel. In a preferred embodiment, grooves 462 may be spaced every 2 inches apart on the exterior side 432 of the middle section 406. While grooves 462 are shown as being V-shaped, it will be appreciated that other shapes are possible including for instance, but not limited to, U-shaped grooves.

[0055] Grooves 462 serve to eliminate or reduce the deformation of panels that may occur when the panels contract and expand during temperature changes, a phenomenon that is sometimes referred to as “oil canning”. For instance, when panel 402 is heated, such as on a warm summer day or where panel 402 is exposed directly to sunlight, the expansion of panel sections 464 is tolerated by grooves 462 becoming slightly narrower. In the reverse when panel 402 is cooled, such as at night, during the winter, or where panel 402 is in the shade, the contraction of panel sections 464 is tolerated by grooves 462 becoming slightly wider. The result is that after repeated expansions and contractions, panel sections 464 are more likely to be remain undeformed.

[0056] FIG. 10 illustrates a series of connectable panels connected at differing locations. Each of panels 402a, 402b, 402c, 402e, 402f, 402g, 402h are identical.

[0057] The panels may be part of a 6 inch module, a 12 inch module, or a module having a different dimensions, such as but not limited to any multiple of 2 inches, 4 inches, 6 inches, 8 inches, 10 inches, etc. The example panels in FIG. 10 are part of a 12 inch module, with grooves being spaced apart every 2 inches.

[0058] The second connecting section 408a of panel 402a is connected to the first connecting section 404b of panel 402b.

[0059] Referring to panel 402a, grooves 462a on panel 402a are spaced apart 2 inches from one another. Each pair of projections 436a forms a space 438a for receiving connectors and diagonal connectors (similar to connectors 8 and diagonal connectors 10 shown in FIG. 1). Projections 436a may be opposite grooves 462a such that in the example 12 inch module, the distance A between the centre of adjacent spaces 438a is also 2 inches apart. Similarly, distance B between spaces 438b on panel 402b would also be 2 inches apart in this example.

[0060] The pair of projections 466a on panel 402a are closest to the second connecting section 408a and form a space 468a that is closest to the second connecting section 408a. On panel 402b, pair of projections 470b are closest to the first connecting section 404b of panel 402b and form space 472b that is closest to the first connecting section 404b.

[0061] Depending on where two panels connect, the length at the connection may vary. FIG. 10 illustrates four different connecting positions for the panels shown. However, and referring to FIG. 9, it will be appreciated that with an alternate number of teeth 416 at the first connecting section 404, the number of different connecting positions can vary.

[0062] Panels 402e, 402f are connected together in a “neutral position”, such that the distance EF between space 468e on panel 402e and space 472f on panel 402f is the same as distance A and distance B. In this example, distance EF would also be 2 inches.

[0063] The distance added or subtracted in moving to different connection positions depends on the distance between the gaps 418 at the first connecting section of each panel. For instance,such added or subtracted distance may be 14 inch when ridge 456 of an adjacent panel is placed in a gap 418 that is one position outwards or one position inwards from the gap 418 used in the neutral position.

[0064] A 14 inch change between gaps 418 will be used to illustrate the changes in the connection shown in FIG. 10. For panels 402g, 402h, ridge 456g of panel 402g is placed in the outermost gap 418h of panel 402h. In this position, distance GH at the connection and between spaces 468g, 472g would be 214 inches, which is 14 inch more than distance EF.

[0065] For panels 402c, 402d, ridge 456c of panel 402c is placed in a gap 418d of panel 402d that is one position more inwards compared to the gap 418f used in the neutral position with panels 402e, 402f. In this position, distance CD at the connection and between gaps 468c, 472d would be 114 inches, which is 14 inch less than distance EF.

[0066] For panels 402a, 402b, ridge 456a of panel 402a is placed in a gap 418b of panel 402b that is two positions more inwards compared to the gap 418f used in the neutral position with panels 402e, 402f. In this position, distance AB at the connection and between gaps 468a, 472b would be 114 inches, which is 14 inch less than distance EF.

[0067] As will be appreciated, the ability to make small adjustments at the connections between panels, such as increasing or decreasing the connection by 14 inch increments, will permit the construction of a wide variety of wall lengths when a series of identical panels are connected. Additionally, and as described further below, the adjustable connections may be used to create a curved or rounded wall.Double System

[0068] While two adjacent panels may be connected together using a single locking mechanism, preferably at least two locking mechanisms are used. A double locking system can provide a better seal between adjacent panels and may also improve the aesthetic look of a finished wall.

[0069] FIG. 11 shows a segment of a formwork for a wall with adjacent panels 502a, 502b. Panel 502a has a single T-shaped ridge 556a on wall 550a (similar to panel 302 shown in FIG. 5). In this example, T-shaped ridge 556a is inserted in the second outermost gap 518a during the construction of the formwork. This provide a single lock at the connection between panels 502a, 502b. However, an outward force due to a rounded wall and / or the weight of concrete poured within the formwork may cause wall 550a of panel 502a and wall 510b of panel 502b to flex or bend such that walls 550a, 510b are not parallel to one another. This can result in the last tooth 516b being separated and spaced from exterior facing side 552a as shown. In addition to such separation being unattractive, the separation may negatively affect the seal at the connection between panels and the stability of the wall.

[0070] In contrast, FIG. 12 shows panels 402e, 402f connected together with a double locking system. In addition to T-shaped ridge 456e, panel 402e also has a J-shaped ridge 458e on wall 450e (similar to panel 102 shown in FIG. 3). Alternatively, J-shaped ridge 458e could be replaced with a T-shaped ridge. In this example, T-shaped ridge 456e is inserted in the second outermost gap 418f during the formwork construction. Additionally, J-shaped ridge 458e touches or is in close proximity to outermost tooth 416f of panel 402f. Together, ridges 456e, 458e act as a double locking system at the connection between panels 402e, 402f. Unlike panels 502a, 502b shown in FIG. 12, the walls 450e, 410f are held together and will remain parallel or substantiallyparallel when outwards forces are exerted on the panels. The double locking system thereby may provide an improved seal and result in a more aesthetic wall without walls 450e, 410f separating at the connections between adjacent panels.Curved Walls with Insulation

[0071] FIG. 13 illustrates a portion of assembled formwork 403 for a curved wall, such as a wall for a cylindrical tank or container. A series of connectable panels, such as those illustrated in FIG. 9, are connected together to form an outer wall 405. For instance, connectable panel 402i is connected to connectable panel 402j. A second series of connectable panels, such as those illustrated in FIG. 9, are connected together to form an inner wall 407. For instance, connectable panel 402k is connected to connectable panel 4021. For such formwork, outer wall 405 will longer than inner wall 407, and the two walls may be connected using connectors 409 and diagonal connectors 411.

[0072] Insulation inserts 413 may be supplied in the size and shape required depending on the connectable panels 402i, 402j and connectors 409. The insulation insert 413 is installed adjacent to the outer wall 405 within the formwork. By way of example, the width X of insulation insert 413 on the exterior side 415 may be around 6 inches, minus the thickness of the connectors 409 and minus an additional small amount (for instance, 1 millimeter) to permit frictionless installation. In a curved wall, since connectors 409 are not parallel, width Y of insulation insert 413 on the interior side 417 is slightly less than width X (for instance, 1 to 2 millimeters less). The insert may generally taper from the exterior side 415 to the interior side 417.

[0073] Preferably, insulation insert 413 is sized and shaped to fit within the formwork 403 with connectable panels forming the outer wall 405, such as connectable panels 402i, 402j, beingconnected in the “neutral position” as described above. For the inner wall 407, changes in the connection locations, such as between connectable panels 402k, 4021, are then made to change the length of the inner wall. In this manner by keeping the connections between connectable panels forming the outer wall consistent and only changing the connections between connectable panels forming the inner wall, a given set of insulation inserts 413 may be used with cylindrical walls of differing diameters.

[0074] In a method of constructing formwork for a curved wall having insulation, a first series of connectable panels, such as connectable panels 402i, 402j, are connected to form an outer wall 405. The connectable panels forming the outer wall are connected at a fixed position. A second series of connectable panels, such as connectable panels 402k, 4021, are connected to form an inner wall 407. The connectable panels forming the inner wall are connected at a different position compared to the fixed position used at the outer wall.

[0075] Panels on the outer wall are connected to panels on the inner wall using connectors. This may be done as the outer wall and / or inner wall is being built.

[0076] The first series of connectable panels are connected to the second series of connectable panels using connectors 409. For example, one end 419 of connector 409 is secured between projections 436i of connectable panel 402i and the opposite end 421 of connector 409 is secured between projections 436k of connectable panel 402k. It will be appreciated that the connection between the connectors and panels forming the outer wall and inner wall may vary depending on the shape of projections 436i, 436k and the shape of ends 419, 421 of connector 409.

[0077] Insulation inserts 413 are inserted adjacent to the exterior wall 405. For large cylindrical structures, such as tanks for biogas plants, a standard set of insulation inserts 413 may be usedfor varying diameters of the cylindrical structures. The insulation inserts 413 may be sized to fit adjacent to panels on the outer wall connected in the neutral position. For example, the panels used to form the outer wall of a 20 meter diameter tank would be connected at the same connection positions as panels used to form the outer wall of a larger 50 meter diameter tank, and all adjustments would be made at the connections between panels forming the inner walls. In such case, the same set of insulation inserts could be used for both the 20 meter diameter tank and the larger 50 meter diameter tank.

[0078] The above detailed description of the embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed above or to the particular field of usage mentioned in this disclosure. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. Also, the teachings of the invention provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments.

[0079] All of the above patents and applications and other references, including any that may be listed in accompanying filing papers, are incorporated herein by reference. Aspects of the invention can be modified, if necessary, to employ the systems, functions, and concepts of the various references described above to provide yet further embodiments of the invention.

[0080] Changes can be made to the invention in light of the above "Detailed Description." While the above description details certain embodiments of the invention and describes the best mode contemplated, no matter how detailed the above appears in text, the invention can be practiced inmany ways. Therefore, implementation details may vary considerably while still being encompassed by the invention disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the invention should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the invention with which that terminology is associated.

[0081] While certain aspects of the invention are presented below in certain claim forms, the inventor contemplates the various aspects of the invention in any number of claim forms. Accordingly, the inventor reserves the right to add additional claims after filing the application to pursue such additional claim forms for other aspects of the invention.

[0082] The foregoing is considered as illustrative only of the principles of the invention.Further, since numerous changes and modifications will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all such suitable changes or modifications in structure or operation which may be resorted to are intended to fall within the scope of the claimed invention.

Claims

CLAIMSWhat is claimed is:

1. A connectable panel for a concrete formwork system comprising: a first connecting section having an outer surface and at least one first connecting member extending a distance Y in a first direction laterally from an opposite side of said outer surface; a middle section having a first end, a second end, an outer surface substantially aligned with said outer surface of said first connecting section, and at least one projection extending a distance X in said first direction on a side opposite to said outer surface of said middle section, said middle section connected at said first end to said first connecting section; a second connecting section connected to said middle section at said second end of said middle section, said second connecting section having at least one second connecting member extending a distance Z in a second direction opposite to said first direction and said second connecting section connectable to said first connecting section of a same connectable panel; wherein the sum of distances Y and Z is equal to or less than distance X.

2. The connectable panel of claim 1 wherein said second connecting section is connected to said middle section by a bend.

3. The connectable panel of claim 1 wherein said at least one first connecting member is a series of teeth and said at least one second connecting member is a hooking element such that said hooking element is insertable between two teeth of an identical connectable panel.

4. The connectable panel of claim 1 wherein said at least one first connecting member is a series of teeth and said at least one second connecting member is two hooking elements such thateach of the two hooking elements is insertable between two teeth of an identical connectable panel.

5. The connectable panel of claim 3 wherein each of said teeth is T-shaped.

6. The connectable panel of claim 3 wherein said hooking element is T-shaped.

7. The connectable panel of claim 3 wherein said hooking element is J-shaped.

8. The connectable panel of claim 1 wherein distance Y and distance Z are the same.

9. The connectable panel of claim 1, wherein when said connectable panel is stacked together with a second panel identical to said connectable panel, said at least one projection of said connectable panel is adjacent to at least one projection of said second panel, said at least one first connecting member of said connectable panel is adjacent to a second connecting section of said second panel, and said second connecting section of said connectable panel is adjacent to at least one first connecting member of said second panel.

10. The connectable panel of claim 1, wherein said outer surface of said middle section has at least one groove to divide said middle section into at least two sections.

11. An assembly of two identical connectable panels for a concrete formwork system stacked together, each of said identical connectable panels comprising: a first connecting section having an outer surface and at least one first connecting member extending a distance Y in a first direction laterally from an opposite side from said outer surface; a middle section having a first end, a second end, an outer surface substantially aligned with said outer surface of said first connecting section, and at least one projection extending a distance X in said first direction on a side opposite to said outer surface of said middle section, said middle section connected at said first end to said first connecting section;a second connecting section connected to said middle section at said second end of said middle section, said second connecting section having at least one second connecting member extending a distance Z in a second direction opposite to said first direction and said second connecting section connectable to said first connecting section of a same connectable panel; wherein the sum of distances Y and Z is equal to or less than distance X. and wherein in said assembly said at least one projection of a first panel of said two identical connectable panels is adjacent to at least one projection of a second panel of said two identical connectable panel, said at least one first connecting member of said first panel is adjacent to said second connecting section of said second panel, and said second connecting section of said first panel is adjacent to said at least one second connecting member of said first second panel.

12. The assembly of claim 11 wherein said second connecting section is connected to said middle section by a bend.

13. The assembly of claim 11 wherein said at least one first connecting member is a series of teeth and said at least one second connecting member is a hooking element such that said hooking element is insertable between two teeth of an identical connectable panel.

14. The assembly of claim 11 wherein said at least one first connecting member is a series of teeth and said at least one second connecting member is two hooking elements such that each of the two hooking elements is insertable between two teeth of an identical connectable panel.

15. The assembly of claim 13 wherein each of said teeth is T-shaped.

16. The assembly of claim 13 wherein said hooking element is T-shaped.

17. The assembly of claim 13 wherein said hooking element is J-shaped.

18. The assembly of claim 11 wherein distance Y and distance Z are the same.

19. The assembly of claim 11, wherein said outer surface of said middle section has at least one groove to divide said middle section into at least two sections.

20. A method of constructing formwork for a curved wall, said method comprising: providing a first series of connectable panels according to claim 1; connecting the first connecting section of panels in said first series with the second connecting section of adjacent panels in said first series at a first connection position to form an outer wall; providing a second series of connectable panels according to claim 1; connecting the first connecting sections of panels in said second series with the second connecting section of adjacent panels in said second series at a second connection position to form an inner wall, wherein said second connection position is different than said first connection position; connecting said first series of connectable panels to said second series of connectable panels using connectors secured at one end to said at least one projection of panels in said first series and secured at the opposite end to said at least one projection of panels in said second series; providing a series of insulation inserts, with each insulation having an exterior side and an interior side, the exterior side being wider than the interior side; and placing said series of insulation inserts between said outer wall and said inner wall with said exterior side of each insulation insert in said series of insulation inserts being placed adjacent to said outer wall.

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