Patent Application
20060284049
This invention relates generally to building construction, and more particularly to coated and/or laminated foam form members for concrete structures.
Concrete pre-cast wall sections and cast-in-place wall sections are used in known building design. One of the popular systems available today is pre-cast concrete tilt-up wall panels. The wall section is first cast horizontally on a firm flat surface, for example, a temporary casting slab or the concrete floor of the building, by the use of a perimeter defining form. The concrete is poured into the area defined by the forms and is then permitted to harden or cure. In order that the concrete panel not adhere to the concrete floor, or surface supporting it, a commercially available chemical coating is first applied to the surface as a bond breaker. After the concrete has hardened to strength a heavy capacity lifting crane is employed to lift, or tilt, the wall section to a vertical position. The wall panel is set upon a concrete foundation or footing at which point it is temporarily supported until permanently incorporated into the building structure.
It is sometimes desirable, for artistic design and/or aesthetic reasons, that relief channels are cast into the flat concrete panel. Typically these relief channels extend horizontally across the concrete panel, but they can also extend vertically. One known method of forming the relief channels in the concrete panels is to fasten wooden strips cut to the desired shape of the relief channel onto the flat pouring surface between the perimeter forms before the concrete is poured. One problem that occurs with wooden strips is that any natural defects in the wood, for example, knots, are transferred to the hardened concrete. Another problem that occurs with wooden strips is the needed repair to the concrete floor that the wooden strips are nailed to. Further problems with wooden strips include moisture absorption which can cause swelling and warping of the strips, sap excretion which can cause discoloration of the concrete in contact with the wood, jagged edges and knots in the wood, and poor release properties of wood.
One attempt to overcome the short comings of wooden reveal strips is to make the reveal strips from plastic materials, for example, polyethylene and polypropylene. However, reveal strips made from these plastic materials are three to five times the cost of wooden strips, and there is a problem of availability of plastic reveal strips in the market place.
In one aspect, a form member for use in casting concrete articles is provided. The form member includes a foam core formed from a foamed polymeric material, and a protective layer covering at least a portion of at least one outer surface of the core. The protective layer includes at least one polymeric material.
In another aspect a form for casting concrete panels is provided. The form includes a plurality of outer perimeter form members connected together to define a casting area, and at least one foam form member. The foam form member includes a core formed from a foamed polymeric material, and a protective layer covering at least a portion of at least one outer surface of the core. The protective layer includes at least one polymeric material.
In another aspect, A method of making a form member is provided. The form member includes a foam core comprising a foamed polymeric material, and a protective layer covering at least a portion of at least one outer surface of the core. The protective layer includes at least one polymeric material. The method includes forming the foam core into a predetermined shape, and applying the protective layer to at least one outer surface of the foam core.
Forms for constructing concrete wall panels, that include coated foam members, are described in more detail below. The coated foam members are light weight, easily cut to size, and are adhesively attached to the flat concrete floor on which the concrete wall panel is cast. The use of an adhesive, for example, a pressure sensitive adhesive and/or two sided adhesive tape, eliminates the use of fasteners, such as, nails, screws, and wood dowels, to fasten the reveal strips to the concrete floor, and thus eliminates the need to repair fastener holes in the concrete floor when the casting of concrete wall panels is complete. The coated foam members are described below as being used as reveal strips in the concrete wall panel form; however, coated foam members can be formed into any shape and used as other parts of the concrete form, for example, chamfer strips and form-board support members with chamfer portions.
Referring to the drawings,
Chamfer strips, 30, 32, 34, and 36 are located in casting area 26 adjacent outer form members 18, 20, 22, and 24. Chamfer strips, 30, 32, 34, and 36 are used to form smooth beveled edges in concrete wall panel 10.
To form relief channels 12 in concrete wall panel 10, reveal/relief strips 38 are located in casting area 26 and extend between opposing outer form members 20 and 24. In the exemplary embodiment, reveal strips 38 are substantially parallel to outer form members 18 and 22 which define the top and bottom of concrete wall panel 10. In alternate embodiments, reveal strips are substantially parallel to outer form members 20 and 24, or at a predetermined angle to outer form members 18 and 22.
Reveal strips 38 and chamfer strips 30, 32, 34, and 36 are formed from a foamed polymeric material and include a protective layer on at least one surface of the foamed polymeric material. Particularly, and referring to
Similar to reveal strips 38, and referring to
Any suitable foamed polymeric material can be used to make reveal strip core 40 and chamfer strip core 52. Suitable foams include, but are not limited to, polystyrene foams, polyvinyl chloride foams, polyurethane foams, phenol-formaldehyde foams, urea formaldehyde foams, polyisocyanurate foams, polyolefin foams, and mixtures thereof. Reveal strip core 40 and chamfer strip core 52, in one embodiment, are formed by cutting a foam blank into the desired shapes. In another embodiment, reveal strip core 40 and chamfer strip core 52 are formed by extruding the foamed polymeric material into the desired shapes. The foamed polymeric material has a density, in one embodiment, of about 1 pound per cubic foot to about 4 pounds per cubic foot. In another embodiment, the density is about 2 pounds to about 3 pounds per cubic foot.
Any suitable film forming polymeric coating material can be used to form protective layers 50 and 54. Suitable film forming polymeric coating materials include, but are not limited to, polyurethane coatings, poly urea coatings, epoxy coatings, plastisol coatings, vinyl coatings, acrylic coatings, polyester coatings, and mixtures thereof. The coating can be applied by any suitable application method, for example, spray coating, dip coating, curtain coating, roll coating and the like. The coating can be applied by automatic or manual application equipment.
The coating is applied, in one embodiment, to a dry film thickness of about 12 micrometers to about 2500 micrometers, in another embodiment, to a dry film thickness of about 25 micrometers to about 1250 micrometers, and in another embodiment, to a dry film thickness of about 125 micrometers to about 750 micrometers. In the exemplary embodiment, the coating material is applied at 100 percent solids to minimize volatile emissions. In other embodiments, the coating material includes an appropriate solvent, for example, organic solvent or water, and is applied at a weight solids less than 100 percent, for example, from about 50 percent to about 99 percent.
Any suitable polymeric material film can be used as a laminate to form protective layers 50 and 54. Suitable polymeric material films include, but are not limited to polyurethane films, poly urea films, epoxy films, plastisol films, vinyl films, acrylic films, polyester films, polystyrene films, and mixtures thereof. The polymeric film can be applied by any suitable lamination method, for example, vacuum forming, adhesive bonding, pressure forming, thermal forming, thermal stamping, and compression forming.
In one exemplary embodiment the polymeric film is laminated to reveal strip core 40 and/or chamfer strip core 52 by heating a sheet of polymeric film to soften the film and then inserting the heated polymeric film into a backform template mold. Next, reveal strip core 40 and/or chamfer strip core 52 is inserted into the backform template mold to laminate the polymeric film to reveal strip core 40 and/or chamfer strip core 52. The polymeric film is then cooled and the laminated core 40 and/or 52 is removed from the mold. The excess polymeric film is then removed from core 40 and/or 52 by cutting and/or planning. In alternate embodiments, a plurality of reveal strip cores 40 and/or chamfer strip cores 52 can be laminated at one time by using a backform template mold that includes a plurality of core templates positioned side by side.
Concrete wall panel 10 is formed by assembling form 14 on floor 28. Outer form members 18, 20, 22, and 24 are secured to floor 28 and each other to define the shape and size of panel 10. Chamfer strips 30, 32, 34, and 36 are secured to floor 28 and outer form members 18, 20, 22, and 24 respectively by any suitable method, for example adhesive and/or adhesive tape. Reveal strips 38 are positioned in casting area 26 and are attached to floor 28 with, for example adhesive and/or adhesive tape. Concrete is poured into mold 14 and permitted to harden and cure. Outer form members 18, 20, 22, and 24 are removed and concrete panel 10 is lifted/tilted from floor 28 by, for example a crane. Any reveal strips 38 and chamfer strips that are embedded in the concrete are removed from panel 10 to form the finished concrete wall panel 10.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
