US20050204698A1

US20050204698A1 - Fiber-reinforced sandwich panel

Info

Publication number: US20050204698A1
Application number: US11/027,677
Authority: US
Inventors: Richard Werner; Kurt Martin
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-11-14
Filing date: 2005-01-03
Publication date: 2005-09-22

Abstract

The present invention may be embodied in a sandwich panel having first and second face panels each panel having a first predetermined thickness and being formed of a fiber-reinforced cementitious material. The sandwich panel further includes support frame for supporting the first and second face panels in a spaced apart configuration. The support frame is formed of a fiber reinforced cementitious material that is continuous with the cementitious material of the first and second face panels. Blocks of rigid insulation are embedded in the sandwich panel for defining a structure of the support frame.

Description

This application is a continuation-in-part of application Ser. No. 09/993,374 filed on Nov. 14, 2001, the contents of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to prefabricated structures, and more particularly, to fiber reinforced wall panels for ease of manufacture of prefabricated structures that can be constructed.

BACKGROUND OF THE INVENTION

Walls of residential and public buildings are generally expected to cover as large an area as possible with as minimum a structural weight as possible. Also, walls are expected to possess proper load bearing capacity, be economical with respect to the combination of construction labor and material costs and on-going maintenance costs, and to be adapted for prefabrication and for use in mounted constructions. Load-bearing concrete walls are generally thick, heavy, and difficult to transport. Also, an uninsulated concrete wall generally has a poor heat insulation value and increasing the insulation value of the concrete wall may be problematic.
Wood walls are lightweight, however, they are limited in strength. In instances where a wall is used as a primary or secondary support member, problems occur due to large deflections/vibrations in the wall, poor fire rating, and poor thermal and acoustic properties. Reinforcing wood walls with concrete can make up for the limited strength of wood floors; however, traditional concrete walls are heavy and labor intensive and experience problems due to crack control (flexure, shrinkage); they require steel reinforcement with a minimum slab thickness.
To provide a wall with improved strength and deflection characteristics, composite materials have been used. However, to insure proper acoustic characteristics, composite wall systems often employed more concrete than would otherwise be necessary to insulate an area from sound vibrations. This of course increases the dead weight of such walls, adds to construction labor and material costs, and requires increased shoring while the concrete is curing. Shoring adds yet further to wall construction cost and time. Excess concrete may also require that the building be built on stronger foundations and have a stronger superstructure. In some areas, ground or soil conditions may militate against such heavier buildings. Also, higher gage joists and stronger beams and columns are required to support the heavier walls. Accordingly, fewer levels can be built in a building of a given weight.
Accordingly, there exists a need for a lightweight and relatively low-cost prefabricated structure for competing in markets preferring concrete structures. The present invention satisfies these needs.

SUMMARY OF THE INVENTION

The present invention is embodied in a fiber-reinforced sandwich panel and a unique composition for the manufacture of prefabricated buildings. The sandwich panel includes first and second face panels, a support frame, and embedded insulation. Each of the first and second face panels has a first predetermined thickness and is formed of a fiber-reinforced cementitious material. The support frame supports the first and second face panels in a spaced apart configuration. The support frame is formed of a fiber-reinforced cementitious material that is continuous with the cementitious material of the first and second face panels. Various mix designs are possible for the cementitious material. The block of embedded insulation defines a structure of the support frame.
The support frame is formed of a fiber-reinforced cementitious material that is continuous with the cementitious material of the first and second face panels. The block of embedded insulation defines a structure of the support frame. The insulation block may be rigid.
In more detailed features of the invention, the sandwich panel may have a height greater than 4 feet, a width greater than about 4 feet, and a thickness between about 2.5 and 8 inches. The thickness of the first panel may be between about 0.25 inches and 2.0 inches, and the thickness of the second panel likewise may be between about 0.25 inches and 2.0 inches. The support frame may have an upper border beam, a lower border beam, and first and second border beams that encompass the insulation. The support frame may further include one or more ribs that have a length extending between the lower border beam and the upper border beam, and that are substantially parallel with the first and second end beams. The ribs may couple the first and second face panels along the length of the ribs. Each of the beams may have a width of between about 2-6 inches, and each of the ribs may have a width of between about 2-6 inches. Due to the fiber-reinforcement, the tensile strength of the cementitious material is increased, thereby eliminating the need for steel reinforcing rods; however, though it is not necessary, each border beam may be further strengthened by reinforcing bar. The cementitious material may have a composition, by weight before cure, of between about 19% and about 41% Portland cement, between about 0% and about 40% fly ash, between about 25% and about 41% sand, between about 1% and about 3% fiber, between about 0% and about 4% acrylic polymer, between about 0.4% and about 0.5% superplasticizer, between about 12% and about 15 % water, between about 0% and about 1% water proofing agent, between about 0% and about 3% color 42.3% sand, about 1.0% polypropylene fiber, about 0.1% superplasticizer and about 14.3% water, and between about 0% and about 3% color (4#/94# of C+F/A) and between about 0% and about 3% color (0.5#/94# of C+FA).
In other more detailed features of the invention, the sandwich panel may include an opening formed by first and second jamb beams that extend between the lower border beam and the upper border beam, and by a sill beam and a header beam that each extend between the first and second jamb beams. The first and second jamb beams are substantially parallel with the first and second end beams and the sill beam and the header beam are each substantially parallel with the lower and upper border beams.
Other embodiments of the invention include a cast wall panel that is modular and, depending on size, includes one or a plurality precast boots that are integrated with the panel. Polypropylene or polyvinyl alcohol fibers are dispersed throughout the panel thereby providing a wall panel with increased strength. The more strength needed to reinforce the panel, the more fibers that can be added. Specifically, the deflection strength of the panel is significantly higher than it would be if the reinforcing fibers were not used. Also, vibrations are reduced due to the fibers, thereby improving acoustic characteristics. The fibers serve a combination of purposes, i.e., insulation, structural and form material
These and other aspects of the invention will be better understood by those of skill in the art with reference to the following drawings wherein like numbers represent like elements throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the invention.
FIG. 1 is a perspective view of a fiber-reinforced sandwich panel, according to the present invention.
FIG. 2 is a cross-sectional elevation view of the fiber-reinforced sandwich panel of FIG. 1, showing a frame structure behind a face panel.
FIG. 3 is a cross-sectional plan view of the fiber-reinforced sandwich panel of FIG. 1.
FIG. 4 is a perspective view of a fiber-reinforced sandwich panel having an opening, according to the present invention.
FIG. 5 is a cross-sectional elevation view of the fiber-reinforced sandwich panel of FIG. 4, showing a frame structure behind a face panel.
FIG. 6 is a cross-sectional plan view of the fiber-reinforced sandwich panel of FIG. 4, showing a jamb of the opening.
FIG. 7 is a cross-sectional elevation view of the windowed fiber-reinforced sandwich panel of FIG. 4, showing a header of the opening.

DETAILED DESCRIPTION

With reference to FIGS. 1-3, the present invention resides in a fiber-reinforced sandwich panel 10 having a lightweight and cost-effective construction. The sandwich panel is formed of a unique cementitious material that allows it to be insect resistant and generally impervious to moisture. Rigid blocks 12 of insulation are embedded in the sandwich panel to provide a desired insulation value to the sandwich panel and to define a support frame 14 that meets desired structural parameters for the sandwich panel.
The sandwich panel 10 may be constructed by pouring a first layer of the cementitious material into a mold (not shown) for forming a casting face panel 15. The rigid insulation blocks 12 are then placed on the first layer. The blocks are sized to define the size of ribs 16 between the blocks and border beams, 18, 20, 22 and 24, around the edge of the sandwich panel. Small nylon spacers (not shown) are placed between the mold and the insulation blocks to define the thickness of the casting face panel.
Optionally, though not necessary, reinforcing bars 26 may be placed in the spaces for the border beams that surround the insulation blocks for adding structural strength to the border beams and the sandwich panel. The reinforcing bar 26 may extend a few inches outside of the sandwich panel to assist in-handling the sandwich panel and for attaching the panel to other structural members. The ribs 16 extend between the upper border beam 18 and the lower border beam 20 and are substantially parallel with the border beams, 22 and 24, at the ends of the sandwich panel. The ribs 16 provide support to the face panels, 15 and 28, and assist in the load bearing characteristics of the sandwich panel.
After placement of the insulation blocks 12 on the first layer, additional cementitious material is poured between, surrounding, and over the blocks to form the border beams, 18, 20, 22 and 24, and the ribs 16. The cementitious material that is poured above the blocks forms an upside face panel 28. Accordingly, the cementitious material forms the face panels 15 and 28, and the support frame 14. After the sandwich panel has initially cured, it is removed from the mold.
The sandwich panel 10 may have a wide variety of configurations for the size of the beams, 18, 20, 22 and 24, the width and spacing of the ribs 16, and the thickness of the casting face 15 and upside face panel 28. A representative sandwich panel may have a width of 16 feet (ft.), a height of 10 ft., and a thickness of 4.25 inches (in.). In conjunction with the sandwich panel thickness of 4.25 in., the beams each may have a width of 4 in., and the ribs may each have a width of 2.5 in. The spacing between the first end border beam 22 and the first adjacent rib of the wall panel may be 18 in. Similarly, the spacing between the second end border beam 24 and the first adjacent rib may be 18 in. The spacing between the ribs may be 26 in. on center.

The cementitious material is reinforced using glass, synthetic, or similar fibers, to provide added structural strength to the sandwich panel 10. A representative composition by weight (uncured) for the cementitious material is provided by the following table:

TABLE 1


(% by weight - uncured cementitious material)

	Material	Preferred Range

	Portland cement	19-41%
	Fly ash	0%-40%
	Sand	25%-41%
	Fiber	1%-3%
	Acrylic polymer	0%-4%
	Superplasticizer	0.4%-0.5%
	Water
	12%-15%
	Water proofing agent
	Preferably Xypex ® (2% of C)	0%-1%
	Color
	4#/94# of C + F/A	0%-3%
	0.5#/94# of C + F/A	0%-3%

The polyfiber may be polypropylene fiber or polyvinyl alcohol fiber cut to lengths of about 0.5 in. to 1.5 in. before mixing with the other materials. The superplasticizer may be Rheobuild® 3000FC, available from Master Builders, Inc. or Cleveland, Ohio. The Water proofing agent may be Xypex® (2% of C). Other formulations for the cementitious material are described in U.S. Pat. No. 6,073,410, titled STRUCTURE AND FORMULATION FOR MANUFACTURE OF PREFABRICATED BUILDINGS. U.S. Pat. No. 6,073,410 is incorporated herein by reference. A polymer may be added to the mix or sprayed on the poured sandwich panel 10 to assist hydration of the cementitious material during cure under low humidity conditions or to enable early handling of the panel. Under controlled environmental conditions, the polymer may be eliminated.
With reference to FIGS. 4-7, the fiber-reinforced sandwich panel 10 of the invention may have an opening 30 for a window or similar passage. As shown in FIG. 5, the opening is surrounded by a header beam 32, a sill beam 34, and first and second jamb beams, 36 and 38. The first and second jamb beams provide support for the upper border beam 18, the header beam 32, and the sill beam 34. Further, the first and second jamb beams, the header beam, and the sill beam may be reinforced with bars 26 to provide additional structural strength surrounding the opening in the sandwich panel.
A representative sandwich panel 10 with an opening 30 may have height of 10 ft., a width of 16 ft., and a thickness of 4.625 in. The casting face panel 15 and the upside face panel 28 may each have a thickness of 0.625 in. The opening in the sandwich panel may have a width of 8 ft. and a height of 4 ft., with the bottom of the opening being 2.5 ft. the from the bottom of the sandwich panel. Each rib 16 may have a thickness of 2.5 in. and may be spaced between the respective end border beam, 22 or 24, and respective jamb beam, 36 or 38, by 24 in.
The fiber-reinforced cementitious material allows the relatively thin casting face panel and upside face panel 28 to have a relatively high strength. The insulation blocks 12 provide a high insulation value to the sandwich panel 10. The sandwich panel has an appearance and impression similar to that of a concrete structure. The configuration of the beams and ribs, and the placement of the reinforcing in the beams, allows the frame 14 of the sandwich panel to have sufficient load-bearing capacity to support a roof structure, additional floor level, or the like. Accordingly, the fiber-reinforced sandwich panel of the present invention provides a cost effective and relatively lightweight, insulated panel for the construction of prefabricated structures or the like.
While the invention has been illustrated and described in detail in the drawings and foregoing description, it should be understood the invention may be implemented through alternative embodiments within the spirit of the invention. Thus, the scope of the invention is not intended to be limited to the illustration and description in this specification, but is to be defined by the appended claims.

Claims

1. A sandwich panel, comprising:

a first face panel having a first predetermined thickness and being formed of a fiber reinforced cementitious material;

the cementitious material having a composition of cement, sand, fiber, a superplasticizer, and water,

a second face panel having a second predetermined thickness and being formed of the same fiber reinforced cementitious material as the first face panel; and

a support frame for supporting the first and second face panels in a spaced apart configuration, the support frame being formed of the same fiber-reinforced cementitious material and being continuous with the cementitious material of the first and second face panels; and an insulation material embedded in the sandwich panel that defines a structure of the support frame;

2. A sandwich panel as defined in claim 1, wherein the first predetermined thickness is between about 0.25 inches and about 2.0 inches and the second predetermined thickness is between about 0.25 inches and about 2.0 inches.

3. A sandwich panel as defined in claim 2, wherein the sandwich panel has a height greater than 4 feet, a width greater than about 4 feet, and a thickness between about 2.5 and about 8 inches.

4. A sandwich panel as defined in claim 1, wherein the support frame comprises an upper border beam, a lower border beam, and first and second border beams that encompass the insulation material.

5. A sandwich panel as defined in claim 4, wherein the support frame comprises one or more ribs having a length extending between the lower border beam and the upper border beam, and being substantially parallel with the first and second end beams, and coupling the first and second face panels along the length of the ribs.

6. A sandwich panel as defined in claim 5, wherein the sandwich panel has a thickness of between about 2.5 inches and about 8.0 inches, the beams each have a width of between about 2 inches and about 6 inches, and the ribs each have a width of between about 2 inches and about 6 inches.

7. A sandwich panel as defined in claim 4, wherein a tensile strength and a compressive strength of each border beam can each be increased by including a reinforcing bar.

8. A sandwich panel as defined in claim 7, wherein the panel includes a reinforcing bar.

9. A sandwich panel as defined in claim 4, wherein the sandwich panel includes an opening formed by first and second jamb beams extending between the lower border beam and the upper border beam, and being substantially parallel with the first and second end beams, by a sill beam extending between the first and second jamb beams and being substantially parallel with the lower and upper border beams, and by a header beam extending between the first and jamb beams and being substantially parallel with the lower and upper border beams.

10. A sandwich panel as defined in claim 9, wherein each beam is strengthened by a reinforcing bar.

11. A sandwich panel as defined in claim 1, wherein the insulation material comprises at least one rigid block of insulation.

12. A sandwich panel as defined in claim 11, wherein the at least one rigid block of insulation is comprised of polystyrene.

13. A sandwich panel as defined in claim 11, wherein the at least one rigid block of insulation is comprised of polyurethane.

14. A sandwich panel as defined in claim 1 wherein the cementitious material is comprised of polyvinyl alcohol fibers.

15. A sandwich panel as defined in claim 1 wherein the cementitious material is comprised of polypropylene fibers.

16. A sandwich panel as defined in claim 1 wherein the composition of the cementitious material further includes a first color that is 4#/94# of C+F/A and a second color that is 0.5#/94# of C+F/A.

17. A sandwich panel as defined in claim 1 wherein the composition of the cementitious material further includes fly ash.

18. A sandwich panel as defined in claim 1 wherein the composition of the cementitious material further includes a waterproofing agent.

19. A sandwich panel as defined in claim 1 wherein the composition of the cementitious material further includes an acrylic polymer.

20. A sandwich panel, comprising:

the cementitious material having a composition by weight before cure of between about 19% and about 41% cement, between about 0% and about 40% fly ash, between about 25% and about 41% sand, between about 1% and about 3% fiber, between about 0% and about 4% acrylic polymer, between about 0.4% and about 0.5% superplasticizer, between about 12% and about 15% water, between about 0% and about 1% waterproofing agent, between about 0% and about 3% color that is 4#/94# of C+F/A, and between about 0% and about 3% color that is 0.5#/94# of C+F/A;