STRUCTURAL PANELS CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Application No. 60/912,328 (filed April 17, 2007), all aforementioned applications including the specifications, drawings, claims and abstracts, are hereby incorporated herein by reference in their entireties.

BACKGROUND

[0002] The present invention relates generally to structural panels, methods of making structural panels, methods of using structural panels for building and construction applications, and methods of using structural panels for concrete pouring applications.

[0003] The use of structural panels in the building and construction industry concentrates on panels of high strength. These conventional panels, however, can have undesirably high weight.

[0004] It is also desirable to use concrete forming panels to enhance the architectural appearance of the finished concrete product. These conventional concrete forming panels, however, also can have undesirably high weight.

[0005] Typically in such applications, the face of the concrete form that will be in contact with the poured concrete needs to be coated with a release agent, for example, diesel or other oil, so that the concrete does not stick to the form during curing, thus permitting the form to be removed from the concrete after it is cured without damage to the surface of the concrete or the concrete form itself, and thus permitting the form to be used again for additional pours. Plain plywood and metal sheets employed for concrete forming require the use of a release agent for each pour. Construction industry experience indicates that treated concrete forming products typically require a release agent after a limited number of pours, typically less than five, due to adherence of the concrete to the surface and damage to the overlay. The protective covering laminated on to the substrate (e.g., resin-impregnated paper) is very thin and of a material that is susceptible to physical damage by the alkalinity of the concrete mix and by the presence of sand, gravel, and other aggregates in the concrete mix and normal handling of the concrete form at the construction site.

[0006] The disadvantages of using these types of products for concrete pouring, versus a durable form that does not require a release agent, include primarily: 1) the additional time and labor required to apply the release agent to form and then to clean the release agent from the form after it is removed from the cured concrete; 2) the additional time and labor required to clean any residual release agent, or staining caused by the release agent, from the surface of the cured concrete after the form is removed; 3) the potential additional time, labor and materials required to repair damage, if any, to the surface of the cured concrete after the form is removed, which damage is caused by failure of the release agent, if any, to provide effective release from the surface of the cured concrete; 4) the potential eventual damage to the form caused by the alkalinity of the concrete mix and the presence of sand, gravel and other aggregates in the concrete mix and the chemicals in the release agent, limiting the useful life of the form and thus increasing the number of forms that need to be purchased and then disposed of; and 5) the potential environmental and related impacts resulting from the use of the release agent, including exposure of workers to the oils, contamination of the construction site, the time, labor, and cost of remediation of the site, and fines imposed by OSHA and/or EPA associated with any such exposure and/or contamination.

[0007] In recent years, in attempts to eliminate, or at least to mitigate significantly, the problems inherent in current pouring form products, as indicated above, various other materials have been employed as pouring surfaces laminated onto the appropriate substrates. These other materials include primarily polyethylene, polypropylene and polyurethane, fiberglass resin (with and without the glass scrim), and various engineered polymers. Construction industry experience indicates that these materials typically also require a release agent after a limited number of pours, typically less than ten pours, and/or are not cost- competitive with current pouring forms and the practices for using them.

SUMMARY

[0008] According to one embodiment of the present invention, a structural panel for use as a building or construction structure may comprise: a core comprising a corrugated composite structure; and first and second plates disposed on opposing sides of the core. The core may comprise a plurality of first rib structures running along a first direction that is disposed on the first plate and a plurality of second rib structures running along a second direction that is disposed on the plurality of first rib structures.

[0009] According to another embodiment of the present invention, a structural panel for use as a building or construction structure may comprise: a core comprising a foamed polymer structure; a first sheet and a second sheet; and first and second plates disposed on opposing sides of the core. The first and second sheets may be polyethylene terephthalate polyester sheets or polyester sheets. The first sheet may be inserted between the core and the first plate and the second sheet may be inserted between the core and the second plate.

[0010] According to another embodiment of the present invention, a method of forming a concrete structure may comprise the steps of: forming a concrete forming structure into which uncured concrete is to be poured; pouring concrete into the concrete forming structure; and removing the concrete forming structure after the concrete has cured. The concrete forming structure may comprise at least one panel having a core and first and second plates disposed on opposing sides of the core. The core may comprise a plurality of first rib structures running along a first direction that is disposed on the first plate and a plurality of second rib structures running along a second direction that is disposed on the plurality of first rib structures.

[0011] According to another embodiment of the present invention, a method of forming a concrete structure may comprise the steps of: forming a concrete forming structure into which uncured concrete is to be poured; pouring concrete into the concrete forming structure; and removing the concrete forming structure after the concrete has cured. The concrete forming structure may comprise at least one panel having a core, first and second plates disposed on opposing sides of the core, and a laminated layer disposed on one of the first and second plates that contact the uncured concrete. The at least one laminated layer may be a flexible membrane comprising a thermoplastic material as a base, alumina, and carbon.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a schematic view of an embodiment of a structural panel according to the present invention.

[0013] FIGS. 2A-2B are front and side views, respectively, of an embodiment of a structural panel with a corrugated composite structure according to the present invention.

[0014] FIGS. 3A-3B are views of an embodiment of a structural panel with a honeycomb structure according to the present invention. FIG. 3A is a perspective view of the structural panel. FIG. 3B is a view of only the honeycomb structure.

[0015] FIGS. 4A and 4B are perspectives view of an embodiment of a structural panel with a flame retardant foamed polymer structure according to the present invention. FIG. 4A shows the structural panel with a polymer foam structure and metal plates. FIG. 4B shows the structural panel of FIG. 4A with Mylar or polyester sheets between the polymer structure and the metal plates.

[0016] FIGS. 5A-5C are cross-sectional views of embodiments of construction panels according to the present invention, which use structural panels.

[0017] FIG. 6 is a perspective view of an embodiment of a concrete forming panel according to the present invention.

[0018] FIGS. 7A-7C are perspective views of embodiments of the concrete forming panel according to the present invention.

[0019] FIG. 8 is a perspective view of an embodiment of a concrete form comprising a plurality of concrete forming panels according to the present invention.

DETAILED DESCRIPTION

[0020] Presently preferred embodiments of the present invention are shown in the accompanying drawings. To the extent possible, the same or like reference numerals have been used to describe same or like parts.

[0021] A structural panel is disclosed that may comprise a light-weight yet strong structure. The structural panel may comprise any one of a corrugated composite structure, a honeycomb structure, or a flame retardant foamed polymer structure. The structural panel may also comprise one or more plates mounted or laminated on each side of the corrugated composite structure, the honeycomb structure, or the flame retardant foamed polymer structure.

[0022] The structural panel may be used as part of a building and construction structure. For example, such applications include the structural panel being part of the following structures: interior/exterior walls or panels, floors, roofs, sub-roof structures, decks/platforms, pallets,

tilt-up walls, bulkheads and marine sheet piling, highway sound barriers; and mobile structures (such as trailers, homes, and shipping containers).

[0023] The additional laminated layers may be attached to the structural panels for forming more aesthetically pleasing construction panels for use in building and construction structures. For example, the additional laminated layers may include one or more of the following: real or faux brick, stone, wood, stucco, or the like, as well as polymer and other materials employed as laminations for functional and/or decorative purposes (such as acoustical tiles, wood panels, paint, plaster moldings, and the like).

[0024] One or more flexible membranes may be mounted on the structural panels to form concrete forming panels which may be used in making concrete forms for concrete pouring applications.

[0025] FIG. 1 presents a perspective view of a general embodiment of a structural panel 100 according to the present invention. The structural panel may take may different forms. In general, the structural panel 100 preferably includes a core 116 and plates 114 on opposing sides of the core 116

[0026] Another embodiment of the structural panel 200 is shown in FIGS. 2A and 2B. This embodiment includes a core 216 comprising a corrugated composite structure. The corrugated composite structure of the core 216 comprises a layer 210 formed by a first series of first rib structures or legs 211 that run along a first direction of the structural panel 200 and a layer 212 formed by a second series of second rib structures or legs 213 that run along a second direction of the structural panel 200. Preferably, the second direction is substantially perpendicular to the first direction.

[0027] The rib structures 211, 213 are elongated and can be any suitable cross-sectional shape including, for example, rectangular, square, triangular, trapezoidal, I-shaped or the like. The presently preferred cross-sectional shape is rectangular. The presently preferred height of the rib structures 211, 213 is in the range of 3 mm to 9 mm, and the presently preferred width of the rib structures 211, 213 is in the range of 3 mm to 9 mm. The length of the rib structures 211, 213 can be modified to suit the particular application.

[0028] The rib structures 211, 213 can be formed from a variety of materials. It is presently preferred that the rib structures 210, 212 be formed from polypropylene.

[0029] The spacing between the rib structures 211, 213 can be varied according to the application and design requirements, such as strength. Preferably the rib structures 211 in the first layer 210 are spaced about 2 to 6 mm apart from one another, more preferably 4 mm apart. Though a different spacing could be used for the rib structures 213 in the second layer 212, it is presently preferred that the same spacing be used as in the first layer 210.

[0030] The first layer 210 and the second layer 212 are preferably connected together to form the core 216. An adhesive layer (not shown) disposed between the first layer 210 and the second layer 212 may be used to attach the rib structures 211, 213 to each other. Also, nails or screws might be utilized. In some embodiments of the present invention, the adhesive layer may be a substance that is not affected or substantially affected by water, alkali, and petrochemicals. The adhesive layer is such to be sufficient to bond the rib structures 211, 213 in such a manner as to be suitable for the performance requirements of the intended application, for example, one or more of the class of moisture-cured urethane, and isocyanate, adhesive systems, or equivalent. In some embodiments of the present invention, the adhesive includes one-part acrylics, two-part acrylics, epoxies, polyurethanes, phenolics, hot-melt adhesives, polyvinyl acetates, ethylene vinyl acetates, pressure-sensitive adhesives, and/or mixtures thereof.

[0031] Plates 214 are placed on either side of the core 216. The plates 214 may be, for example, formed from aluminum, anodized aluminum, or other suitable material such as steel. It is presently preferred that the plates have a thickness in the range of 0.1 mm to 0.4 mm. An adhesive layer may be used to attach the plates 214 to the core 216. Also, nails or screws might be utilized. In some embodiments of the present invention, the adhesive layer may be a substance that is not affected or substantially affected by water, alkali, and petrochemicals. The adhesive layer is such to be sufficient to bond the different materials of the plates 214 and the core 216 in such a manner as to be suitable for the performance requirements of the intended application, for example, one or more of the class of moisture- cured urethane, and isocyanate, adhesive systems, or equivalent. In some embodiments of the present invention, the adhesive includes one -part acrylics, two-part acrylics, epoxies, polyurethanes, phenolics, hot-melt adhesives, polyvinyl acetates, ethylene vinyl acetates, pressure-sensitive adhesives, and/or mixtures thereof.

[0032] One of the notable improvements over the prior art, such as in the art of the manufacture of signs, is the fact that the rib structures 211 extend in a direction substantially

perpendicular to the direction of the rib structures 213, as opposed to running parallel to each other. This improvement allows embodiments of the structural panel 200 to maintain essentially equal strength in both directions across the plane of the panel, thereby minimizing deflection under an equal load, as may be encountered when used in concrete forms.

[0033] When assembled, the overall thickness of the structural panel 200 can be about 1/2 inch, although the thickness can vary depending on the application. For example, thicknesses such as 3/8, 1/2, 5/8, 3/4, 7/8, and 1 inch can be used. The structural panel can have a variety of widths, such as 48 or 60 inches, and a variety of lengths, such as 72, 96, 120 and 144 inches.

[0034] FIGS. 3A-3B show another embodiment of the structural panel 300 according to the present invention. This embodiment includes a core 316 that is substantially a honeycomb structure similar in at least some respects to that used in the manufacture of aircraft. The honeycomb structure of the core 316 includes a collection of slender members connected together by conventional means to form walls 311. These walls 311 preferably are rectangular in shape and have a density of about 1.5 - 2.0 lb/ft ³ , a width of about 2-8 mm and a length of 6-24 mm, preferably a density of 1.8 Ib/ lb/ft ³ , a width of 4 mm and a length of 13 mm. The skins (i.e., the plates 314) are preferably galvanized, or stainless steel or aluminum. In some embodiments of the present invention, the honeycomb material, cell structure and wall thickness is such that the combination provides the required strength and weight, and is cost-competitive, for the intended application. The dimensions of the walls 311 and the spacing between them can be modified to suit the particular application.

[0035] The honeycomb structure can be made from various types of materials. It is presently preferred that it be formed from metal (such as galvanized or stainless steel or aluminum). Other materials, however, such as polymer or paper, may also be used.

[0036] Plates 314 are placed on either side of the core 316. The plates 314 may be, for example, formed from galvanized steel or aluminum. It is presently preferred that the plates have a thickness in the range of 0.1 mm to 0.4 mm.

[0037] An adhesive layer (not shown) may be disposed between the plates 314 and the core 316 to attach the plates 314 to the core 316. Because the contact area between the edge of the honeycomb structure of the core 316 and the plates 314 is small, an extremely strong adhesive preferably is used to attach the plates to the honeycomb structure. A notable

improvement over the prior art is the use of an adhesive layer that is sufficient to bond the different materials of the core 316 and the plates 314 in such a manner as to be suitable for the performance requirements of, and cost-competitive for, the intended application, for example, one or more of the class of 2-part epoxy adhesive systems, or equivalent.

[0038] When assembled, the overall thickness of the structural panel 300 can be about 1/2 inch, although the thickness can vary depending on the application. For example, thicknesses such as 3/8, 1/2, 5/8, 3/4, 7/8, and 1 inch can be used. The structural panel can have a variety of widths, such as 48 or 60 inches, and a variety of lengths, such as 72, 96, 120 and 144 inches.

[0039] FIGS. 4A-4B shows other embodiments of the present invention in which the structural panel 400 comprises core 416 formed of a flame retardant foamed polymer structure. The foamed polymer structure could be, for example, polyvinyl chloride (PVC), such as 30% volume PVC foam. Other foamed polymers can be used, if flame retardancy is not required and they provide the performance and other performance properties required for the intended application. The presently preferred height of the core 416 is 3/4 inch but other heights can be used, such as about 3/8, 1/2, 5/8, 3/4, 7/8, or 1 inch.

[0040] Plates 414 may be provided on either side of the core 416. The plates 414 may be formed from polyester and/or metal. If polyester is used, for example, the plates 414 may be a concrete release overlay such as Maxam's MCO™, or a decorative surface. If metal is used, for example, the plates 414 may be aluminum. It is presently preferred that each of the plates 414 have a thickness in the range of 0.01 mm to 0.25 mm. In FIG. 4A, the plates 414 are attached to either side of the core 416 and an overlay surface on one or both sides at 414; however an embodiment of the present invention may have only one metal or polyester layer plate 414 attached to the core 416.

[0041] FIG. 4B shows a modification of the structural panel of FIG. 4A in which a polyethylene terephthalate polyester (Mylar) sheet or polyester sheet 413 is inserted between the metal plates 414 and the polymer structure 416. The addition of the Mylar or polyester sheet is also an advancement over the prior art due to the additional structural enhancement with very low additional weight, and the adhesive system used to attached these layers together.

[0042] An adhesive layer (not shown) may be disposed between the plates 414 and the core 416 to attach the plates 414 to the core 416. One notable advancement over the prior art is the use of an adhesive system used to connect the plates 414 to the core 416 in the structural panel 400 of FIG. 4A. The adhesive system may use the polyester layer at 413 as a carrier and be coated on one or both sides depending on whether plate 414 is attached. The adhesive layer preferably is sufficient to bond the different materials of the core 416 and plates 414 in such a manner as to be suitable for the performance requirements of, and cost-competitive for, the intended application, for example, one or more of the class of moisture-cured urethane, and isocyanate, adhesive systems, or equivalent. The adhesive system may include compounds that include those inherent in the materials being bonded together.

[0043] When assembled, the overall thickness of the structural panel 400 can be about 1/2 to 1 inch thick, although the thickness can vary depending on the application. For example, thicknesses such as 3/8, 1/2, 5/8, 3/4, 7/8, or 1 inch can be used. The structural panel can have a variety of widths, such as 48 or 60 inches, and a variety of lengths, such as 72, 96, 120 and 144 inches.

[0044] The various embodiments of the structural panels 200, 300, and 400 as seen in FIGS. 2-4 can be used in a variety of applications, such as building and/or construction applications. For example, the embodiments of the structural panels may be used as part of the following structures: interior/exterior walls or panels, floors, roofs, sub-roof structures, decks/platforms, pallets, tilt-up walls, bulkheads and marine sheet piling, highway sound barriers; and mobile structures (such as trailers, homes, and shipping containers). The building and construction industry often require panels of high strength. The structural panels according to the present invention can be advantageously used as light weight alternatives to various conventional heavier solid forms of panel, while providing the necessary strength.

[0045] The use of light weight yet high strength panels can provide cost savings in the construction of various building structures due to the fact that less time and effort is necessary for the placement of the structural panels during the construction process. Fewer men and/or less costly equipment may be utilized when fixing lighter structural panels in place. For example, in one application of tilt-up walls, usually large concrete walls are used to form large warehouse walls, such as those used in super distribution centers. The wall is usually formed on the ground and a footing with a trench is formed at the spot where the wall is to be planted and erected so as to be part of the wall of the warehouse. The concrete wall

may weigh many tons and costly crane equipment is typically used to erect the wall (i.e., tilt- up the wall upward) so that it is planted into the trench and secured to the final structure. If warehouse wall is instead made from the structural panel, like those disclosed in FIGS. 2A- 4B, less costly equipment will be necessary to lift and fix the walls into place due to its lighter weight.

[0046] In alternative embodiments of the present invention, the structural panels 200, 300 and 400 may include layers laminated onto the structural panels to form construction panels 501, as shown in FIGS. 5 A through 5C. For example, some laminated layers can be attached to one or more sides of the structural panel, such as one with a corrugated structure as shown in FIGS. 2A-2B, a honeycomb structure as shown in FIG. 3 A, or a polymer structure as shown in FIG. 4A or 4B. Some laminated layers may include one or more of the following: real or faux brick, stone, wood, stucco, or the like, as well as polymer and other materials employed as laminations for functional and/or decorative purposes (such as acoustical tiles, wood panels, paint, plaster moldings, and the like).

[0047] FIG. 5A shows a laminated layer 503 of acoustical tiles mounted on one side of a structural panel 200, 300, or 400, in which the layer 503 is mounted using an adhesive. FIG. 5B shows a laminated layer 504 of wood on both sides of a structural panel. FIG. 5C shows one laminated layer 505 of a plaster molding on one side of the structural panel 200, 300, or 400, and another laminated layer 506 of paint on the other side. The use of additional layers can be used to provide a more aesthetically structure for either indoor or outdoor use. For example, such applications for the construction panel in which the construction panel is a permanent part of the finished structure include: interior/exterior walls or panels, floors, roofs, sub-roof structures, decks/platforms, and the like.

[0048] In yet another embodiment, the structural panels (with or without the one or more other laminated layers) can include anti-pest and/or anti-fungal/mold/mildew capabilities in building and/or constructions applications. To add such capabilities, a long lasting natural anti-pest additive is used, for example, the additives disclosed in U.S. provisional application 60/721972, filed on September 30, 2005, and U.S. Patent application 11/529740, filed September 29, 2006, both herein incorporated by reference in their entireties. These additives will typically be incorporated in the outer layer of the panel.

[0049] FIG. 6 shows another embodiment of the present invention in which a structural panel 600 (which can be the structural panel 200 in FIG. 2A-2B; 300 in FIG. 3A; or 400 in FIG. 4A or 4B) can be used as part of a concrete forming panel 603. Such concrete forming panels can be used in the formation of concrete forms used to create concrete structures such as concrete walls, garage floors, pillars/columns, and pre-casted items (such as Jersey barriers or walls). Using structural panels according to the present invention provides concrete forming panels that are light weight, which can greatly ease the time and effort necessary during the construction process.

[0050] The use of light weight concrete forming panels should include material, such as one or more flexible membranes 602, that facilitates the separation of the concrete forming panel from the finished concrete product. The flexible membrane 602 may include the flexible membrane as disclosed in U.S. Provisional Application 60/810,156, entitled "Flexible Release Agent-Free, Multiple-Use Materials Employed for Concrete Pouring Forms and Methods of Making and Using the Same," filed June 2, 2004, (herein incorporated by reference in its entirety). Such a flexible membrane may be used to form concrete products that exhibit excellent release properties, and that could be reused repeatedly without the use of a release agent. According to one embodiment of the present invention, the flexible membrane 602 may include ethylene propylene and a diene monomer and/or a terpolymer of ethylene, propylene and a diene monomer. In some embodiments of the present invention, the flexible membrane 602 includes a polymer comprising butylene monomers and/or a polymer comprising chlorosulfonated polyethylene, such as, by way of example only and not by way of limitation, Hypalon®. In some embodiments of the present invention, the flexible membrane comprises an elastomer, a vulcanizable elastomer, a vulcanized elastomer, a poly- rubber blend. In some embodiments of the present invention, the flexible membrane 602 includes a combination/mixture of at least some of these compositions. In some embodiments of the present invention, the flexible membrane 602 is in accordance with ASTM-D-1418-64. In some embodiments of the present invention, the flexible membrane is a rubber product.

[0051] In some embodiments of the present invention, the flexible membrane may comprise a thermoplastic material (such as polyvinyl chloride (PVC), polypropylene, high density polyethylene (HDPE) or other type of polyethylene) as a base; alumina (Al ₂ O ₃ ); and/or carbon. For example, the flexible membrane may comprise an amount by weight of about

50-95% of thermoplastic material (preferably 63.75% of HDPE), about 25% to 45% of alumina (preferably 35% of alumina), and preferably about 1.25% by weight of carbon (such as carbon black). Of course, other amounts of thermoplastic material, alumina, and carbon may be used. Also, the carbon may be selected from the group consisting of activated carbon, non-activated carbon, carbon fibers, and/or carbon black.

[0052] The flexible membrane 602 according to an embodiment of the present invention provides easy, quick, and clean release from cured concrete without the use of a release agent, such as form oil or diesel oil or chemicals, of either a barrier or reactive type. The concrete forming panel 603 can be used to construct concrete forms. By way of example only and not by way of limitation, the concrete pouring form may be usable for, in some embodiments, at least 20 pours, at least 25 pours, at least 30 pours, and in some embodiments even more than 30 pours, without the use of one or more release agents. In some embodiments of the present invention, the quick, easy, and clean release properties of the flexible membrane 602 are such that the surfaces of both the cured concrete and the flexible membrane 602 may be smooth and undamaged after the concrete form made from the concrete forming panel 603 is removed from the cured concrete and/or visa-versa. The concrete forming panel 603 may be used to construct and disassemble concrete pouring forms using commercially available building and constructions industry tools, equipment, and standard practices.

[0053] Without being bound to theory, it is believed that the quick, easy, and clean release capability of the flexible membrane 602 without release agents of some embodiments of the present invention is provided at least in part by the low surface energy of the flexible membrane. The low surface energy may result from the combination of the types and amounts of material employed in the flexible membrane 602 and the method by which the flexible membrane is manufactured. Surface energy may be determined, for example, by measuring the contact angle formed by a droplet of distilled water upon the membrane 602. The more that the water droplet "beads up," the greater the contact angle is, and the lower the corresponding surface energy is. The flexible membrane can have a surface energy of less than or approximately equal to about 25 or 30 dynes/cm.

[0054] In some embodiments of the present invention, such as, by way of example only and not by way of limitation, embodiments utilizing ethylene propylene and a diene monomer and/or a terpolymer of ethylene, propylene and a diene monomer, it is possible to remove

residual concrete mineral dust, if any, from, and perform a general cleaning of, the surface of the flexible membrane by simple hand-dusting with a cloth, or rinsing with water employing a cloth or brush (e.g., commercially available non-metal bristle brushes), as appropriate, after the structural panel is removed from the cured concrete. Some embodiments of the present invention may incorporate, in the flexible membrane 602, functional or decorative surface textures, patterns, or designs, which surface treatments also do not require the use of release agents for quick, easy, and clean release or any change in the method of cleaning as set forth above. In some embodiments of the present invention, the flexible membrane 602 has a thickness of at least approximately 40 mils. In other embodiments of the present invention, thicker or thinner flexible membranes may be used.

[0055] The concrete forming panel 703 may take a variety of forms. For example, FIG. 7 A show an embodiment of the present invention in which concrete forming panel 603 comprises a structural panel 700 with a corrugated composite structure of the type shown in FIGS. 2A and 2B. The flexible membranes is attached to the structural panel 700 using an adhesive layer. The adhesive layer may comprise any suitable adhesive. By way of example only and not by way of limitation, an adhesive according to U.S. Patent No. 4,657,958 to Feldhouse, et al., issued April 14, 1987, the contents of which are incorporated herein in their entirety, may be utilized to bond a flexible membrane 602 to the metal plates of the structural panel 700. Other adhesives may be utilized as well. Some embodiments of the present invention maybe practiced utilizing adhesive number 92256 obtainable from Portals Plus Inc. of Chicago, Illinois, U.S.A. Any adhesive or other substance that may be utilized to sufficiently connect the flexible membrane 602 to the metal plates of the structural panel 700 may be used. Also, nails or screws might be utilized, at least when the portions of the nails or screws would not leave an impression in the concrete product (e.g., nails may be utilized to secure portions of the flexible membrane 602 that do not come into contact with the concrete, nail heads may be "covered over" with a patch, etc). In some embodiments of the present invention, the adhesive layer may be a substance that is not affected or substantially affected by water, alkali, and petrochemicals. In some embodiments, the bond resulting from the use of the adhesive layer(s) may remain intact and effective for the useful commercial life of the structural panel 200 (e.g., for at least 20, 30, or 30+ pours, etc.). In some embodiments of the present invention, the adhesive includes one-part acrylics, two-part acrylics, epoxies, polyurethanes, phenolics, hot-melt adhesives, polyvinyl acetates, ethylene vinyl acetates, pressure-sensitive adhesives, and/or mixtures thereof.

[0056] The concrete forming panel 703 may be, by way of example only, attached and secured to a concrete forming frame or otherwise positioned and secured in the desired orientation or alignment in a free-standing configuration using, for example, screws or clamps. Holes in the concrete forming panel 703 remaining after the screws are removed can be resealed, in the field, with material to restore the concrete forming panel 703 to its original condition.

[0057] In an embodiment of the present invention, two flexible membranes may be bonded or otherwise connected to opposite sides of the structural panel, thus creating a dual-faced concrete forming panel with a useful commercial life of, by way of example, at least 40, 50, or 60+ concrete pours (i.e., at least 20, 25, 30+ pours respectively for each face of the dual- faced concrete forming panel used as a concrete form). In yet other embodiments of the present invention, a composite material with desirable release characteristics vis-a-vis cured concrete, such as one according to Provisional Application No. 60/559,005, entitled "Release Agent-Free, Multiple-Use, Polymer-Based Composite Materials Employed for Concrete Pouring Forms and Methods of Making and Using Same," filed April 5, 2004, is connected to one opposite side of the substrate, thus creating a dual-faced concrete forming panel with a useful commercial life as just recited.

[0058] In some embodiments of the present invention, the flexible member may be subjected to a surface treatment to improve adhesion between the flexible member and the metal plates of the structural panel. The surface treatment may be selected, by way of example only and not by way of limitation, from the group of a corona discharge, a flame treatment, a plasma treatment, and/or combinations thereof.

[0059] The concrete forming panel 703 of FIG. 7A as disclosed may have the following advantages: (1) a 1/2" thick section is equivalent to plywood; (2) the weight of a 1/2" thick section is half the weight of 3/4" thick plywood; (3) there is no organic components to support rot, mold, or mildew; and (4) there is low maintenance and life-cycle costs.

[0060] FIG. 7B shows another embodiment of the present invention in which the concrete forming panel 703' may comprise structural panel 700' with a honeycomb structure such as the one shown in FIG. 3A. An adhesive layer similar to the adhesive layer discussed in relation to the embodiment of FIG. 7A may be used to attach the flexible membrane(s) 602 to the metal plates of the structural panel. The concrete forming panel may be, by way of

example only, attached and secured to a concrete forming frame or otherwise positioned and secured in the desired orientation or alignment in a free-standing configuration using, for example, screws or clamps. Holes in the concrete forming panel remaining after the screws are removed can be resealed, in the field, with material to restore the form to its original condition. In an embodiment of the present invention, two flexible membranes may be bonded or otherwise connected to opposite sides of the structural panel, thus creating a dual- faced concrete forming panel with a useful commercial life of, by way of example, at least 40, 50, or 60+ concrete pours (i.e., at least 20, 25, 30+ pours respectively for each face of the dual-faced structural panel used as a concrete form). In some embodiments of the present invention, the flexible member may be subjected to a surface treatment to improve adhesion between the flexible member and the metal plates of the structural panel. The surface treatment may be selected, by way of example only and not by way of limitation, from the group of a corona discharge, a flame treatment, a plasma treatment, and/or combinations thereof.

[0061] The concrete forming panel 703' of FIG. 7B may have the following advantages: (1) the strength of the a 1/2" thick section is several times that of 3/4" thick plywood; (2) the weight of a 1/2" thick section is similar or less then the weight of 3/4" thick plywood; (3) there is no organic components to support rot, mold, or mildew; and (4) there is low maintenance and life-cycle costs.

[0062] FIG. 7C shows another embodiment of the present invention in which concrete forming panel 703" comprises a structural member 700" comprising a flame retardant foamed polymer structure, such as the one shown in FIG. 4 A or 4B. An adhesive layer similar to adhesive layer discussed in relation to the embodiment of FIGS. 7A-7B or other adhesive may be used to attach the flexible membrane 602 to the metal plates of the structural panel 700". The concrete forming panel 703" may be, by way of example only, attached and secured to a concrete forming frame or otherwise positioned and secured in the desired orientation or alignment in a free-standing configuration using, for example, nails, screws or clamps. Holes in the concrete forming panel remaining after the screws are removed can be resealed, in the field, with material to restore the form to its original condition. In some embodiments, the concrete forming panel may be cut or sawed, nailed or screwed into, framed and clamped and otherwise used, handled and stored in the same manner as, and employing the same commercially available tools and equipment and standard industry

practices currently employed with, non-metal concrete forming products employed in normal building and constructions applications and conditions. In an embodiment of the present invention, two flexible membranes may be bonded or otherwise connected to opposite sides of the structural panel, thus creating a dual-faced concrete forming panel with a useful commercial life of, by way of example, at least 40, 50, or 60+ concrete pours (i.e., at least 20, 25, 30+ pours respectively) for each face of the dual-faced concrete forming panel used as a concrete form). In some embodiments of the present invention, the flexible member may be subjected to a surface treatment to improve adhesion between the flexible membrane and the metal plates of the structural panel. The surface treatment may be selected, by way of example only and not by way of limitation, from the group of a corona discharge, a flame treatment, a plasma treatment, and/or combinations thereof.

[0063] The concrete forming panel 703" of FIG. 7C may have the following advantages: (1) the strength and weight of the structural panel is equivalent or better than plywood of similar thickness; (2) the structural panel can be cut with normal wood tools; (3) the edges of the structural panel do not require sealing; (4) there is no organic components to support rot, mold, or mildew; and (4) there is low maintenance and life-cycle costs.

[0064] The concrete forming panel of FIGS. 7A-7C can all be used in concrete pouring applications. For example, concrete forming panels may be arranged using wooden braces and tie rods or big metal frames. A method of pouring concrete using one or more structural panels of the present invention may include the actions of providing a flexible membrane, providing a structural panel, bonding the flexible membrane to the structural panel to provide a concrete form that may be released from cured concrete without using a release agent such that at least one surface of the concrete form and at least one surface of the cured concrete are left smooth and undamaged. The flexible membrane may be bonded to the structural panel using an adhesive. The method may also include the steps of pouring concrete into the concrete form such that the flexible membrane comes into contact with the poured concrete, allowing the poured concrete to cure, and separating the cured concrete from the concrete form, in the absence of a release agent, to provide one or more corresponding flat or curved surfaces on the cured concrete, which surfaces require little to no finishing work.

[0065] As can be seen in FIG. 8, concrete forming panels can be used to create a concrete form having a rectangular cavity or other suitable form with the flexible membrane 602 forming the interior surfaces of the concrete form. The resulting concrete pour form is filled

with a concrete composition comprising a very high alkalinity cement mix with various aggregates of various sizes and shapes, including sand and gravel with sharp edges. No form oil or other oils or release agents is applied to the surfaces of the flexible membrane prior to pouring the concrete composition into the concrete form. The concrete in the concrete form is vibrated and tamped to remove trapped air and to condense the composition in accordance with standard building and construction industry practice. The concrete composition is then cured in place in the container.

[0066] When the concrete has cured, the container is then disassembled and the cured concrete block is removed. The flexible membrane forming the interior faces of the walls of the container would be released easily from the cured concrete block when the concrete forming panel samples are disassembled and removed from the cured concrete block. The surfaces of the flexible membrane would be smooth, and no damage to any of the surfaces of the flexible membrane would be observed. Further, any residual concrete mineral dust remaining on the surface of the flexible membrane is washed off easily with water.

[0067] To show the applicability of the panels as concrete forming structures, a test pour was conducted to compare a panel according to an embodiment of the present invention with a standard 3/4 inches plywood forming panel. The panel (hereinafter referred to as Panel A) comprises a corrugated composite structure and first and second plates disposed on opposing sides of the core. The core comprises a plurality of first rib structures running along a first direction that is disposed on the first plate and a plurality of second rib structures running along a second direction that is disposed on the plurality of first rib structures. Both Panel A and the plywood panel had Maxam's MCO™ facing on one face, and the plywood panel also had MDO on the back face. The samples were placed in 2' x 8' steel frames for the pour and a concrete section approximately 2.5" thick and 8' high was poured. The purpose was to compare the deformation of the concrete wall due to deflection of the face material under load in a real-world field test. A straight edge was placed at the exact center where the arc of deflection was the greatest and used as a reference to measure the deflection at the edges. The following deflections were measures:

[0068] The deflection in the 3/4" plywood was typical. The maximum variance between Panel A and the plywood panel was only 0.074". There was no measurable deflection in the vertical direction on either panel.

[0069] Another test was conducted to evaluate the deflection under load of Panel B, which is a profile-core, all-composite forming panel comprising a corrugated composite structure and first and second plates disposed on opposing sides of the core. The core comprises a plurality of first rib structures running along a first direction that is disposed on the first plate and a plurality of second rib structures running along a second direction that is disposed on the plurality of first rib structures. Panel B had Maxam's MCO™ facing on one face and was the standard nominal 0.500" thick. The sample was placed in a 2' x 8' steel frame which had an airbag above it to apply a measured uniform loading across the face. The deflection under load in the center of each section was compared to and reduced by the average deflection of the steel framing on either side to get a measure of the actual deflection of Panel B. The average deflection of Panel B was 0.1004 inches at 7.0 PSI and 0.1686 inches at 10.4 PSI. The deflection of Panel B was consistent across the test bed.

[0070] While the present invention has been described with respect to what is presently considered to be the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements.