Process for making insulated concrete tilt-up walls and resultant product
In a method of making insulated concrete tilt-up panels, an insulating material such as polystyrene is formed into a desired shape corresponding to the panel shape. Attachment grooves are formed across the surface of the insulating material. Preferably, the attachment grooves have a substantially triangular cross-section. The insulating material is laid groove-side-up in a concrete form and wet concrete is poured into the form. The concrete fills the grooves, attaching the insulation to the concrete panel. When the concrete is cured, the panel may be stood up and set in place so that the insulating material forms the exterior surface of the panel. A finishing material may be applied to the exterior surface of the panel. A panel set for use in constructing low-income residential housing includes four concrete tilt-up panels. The insulating material and concrete forms may be prepared in the quantity desired for the entire construction project and transported to a casting area at the construction site. The panels may be rapidly cast and assembled, reducing the time and labor required to complete the project.
This application claims the benefit of co-pending provisional application No. 60/937,027 filed Jun. 25, 2007.
FIELD OF INVENTIONThis invention relates to concrete wall construction. This invention relates particularly to a process for creating insulated concrete tilt-up wall panels and the resultant products.
BACKGROUNDBuilding structures using tilt-up concrete wall panels are well known in the art. They can significantly reduce the initial cost of construction, increase the life of the structure and reduce maintenance cost. Tilt-up panels are made under controlled conditions and the exterior surface can be inexpensively finished with rollers to shape an attractive product. Such panels can be pre-cast, fabricated and stored in the factory and then transported to the building site, or made in-situ, forming the panels at the building site. Walls, and therefore buildings, can be assembled rapidly using the panels.
In general, tilt-up concrete panels are made by attaching a concrete form having the dimensions of the desired panel to a casting surface, then filling the cavity of the concrete form with freshly mixed concrete and letting the concrete cure. Concrete forms are conventionally constructed on-site as needed for each building and made of wood or metal; these forms are removed after the panel is cured. Alternatively, the forms may be pre-made forms of foam, plastic or metal into which the concrete is poured; these forms become integral with the panel. Metal ties such as rebar span the forming panels to connect and maintain the positions of the opposed forming panels as the concrete is placed. Often the ties are formed into grids, webs, chairs, or a combination thereof. The ties are left in the concrete as it hardens, and thus reinforce the strength of the panels, as well as provide support for connecting the formed panels to each other when constructing a continuous wall. The edges of the tilt-up panels may be beveled to provide some tolerance when placing the panels together in the wall, and the joints created between the tilt-up panels are caulked.
Concrete walls have large thermal mass, but are poor insulators. That is, once the heat or cold is absorbed by the concrete, it is conducted unfortunately rather well. It would therefore be advantageous to insulate a concrete tilt-up panel. Further, it would be more advantageous to insulate the tilt-up panel along its exterior surface, so that the thermal mass of the concrete is cooled or heated by the environment inside the structure rather than from the outside. A wall using such panels would reduce energy consumption of heating and air conditioning units by regulating the temperature of the interior space.
Some known methods of insulating tilt-up panel walls use insulating materials commonly known in the construction industry, such as rigid pre-formed foam panels or spray foam that hardens. However, it is difficult to attach rigid foam panels to the relatively smooth finished exterior surface of a concrete tilt-up wall, and spray foam does not stick in place long enough to harden. A common solution is to insert a layer of insulation between two layers of concrete, either during formation of a single panel or once the panels are in place in the wall. This solution does not take full advantage of the thermal mass of the tilt-up wall, allowing part of the wall to heat or cool without insulation while providing a smaller thermal mass for regulation of the interior temperature. Further, the uneven heating and cooling of the wall may weaken its structural integrity. A tilt-up wall with a fully insulated thermal mass is needed.
Therefore, it is an object of the invention to provide a process for creating insulated tilt-up concrete panels. It is a further object that the tilt-up concrete panels be individually insulated on the exterior surface. It is another object of the invention to provide a process for creating insulated tilt-up concrete panels which improves the efficiency of on-site panel construction.
SUMMARY OF THE INVENTIONThis invention is a method of making insulated concrete tilt-up panels and the resultant products. An insulating material is formed into a desired shape. Preferably, the insulating material is pre-formed rigid polystyrene. A standard panel typically has a substantially rectangular insulating material, while custom panels may have irregular shapes, such as cutouts for a door or window. Multiple panels of a given shape may be pre-made for use in a construction project where the panel shapes are repeatedly used.
One or more attachment grooves are formed across the surface of the insulating material. Preferably, the attachment grooves have a substantially triangular cross-section. One edge of the insulating material may be formed with a tongue and the opposing edge formed with a groove, or the edges may be interlocking, such that one panel may be easily and securely attached to another panel.
One or more segments of insulating material are laid horizontally within a conventional concrete tilt-up panel form. If multiple segments are used in a single form, each seam between the segments may be sealed to prevent seeping of wet concrete. The attachment grooves face up to receive the concrete. The concrete is poured onto the insulating material until the form is filled. The concrete fills the triangular grooves, thus attaching the insulation to the concrete panel. When the concrete is cured, the panel may be stood up and set in place so that the insulating material forms the exterior surface of the panel.
A combination of four panels, each having a different shape, is disclosed which may be used to build the exterior walls of multiple models of residential homes, such as those in a subdivision of low-income housing. The insulating material may be prepared in the quantity desired for the entire construction project and transported to a casting area at the construction site. The panels may be rapidly cast and assembled, reducing the time and labor required to complete the project.
Insulating Material
The insulating material 12 is preferably a substantially rigid insulating foam which may be cut with a hot knife and will not be damaged when wet concrete is poured onto it as explained below. Further, the insulating material 12 preferably has an R-value, used in the art to measure resistance to heat flow, of four per inch or higher. Two examples of such material which are known in the art are molded expanded polystyrene (“MEPS”) and extruded expanded polystyrene (“EEPS”). In the present invention, EEPS is preferred due to its higher resistance to water vapor and heat flow. The insulating material 12 most preferably has an R-value of 4.5 per inch. Other polymer foams having a higher density and R-value, such as polyisocyanurate or polyurethane, may be used.
Some MEPS and EEPS insulating foam has a thin material, called facing, applied to its outer surfaces in order to protect the foam from damage during handling. Some types of facing may also form a vapor barrier and increase the insulating material's 12 resistance to heat flow. The facing may be a polymeric film, aluminum foil, kraft paper, or another thin protective layer. In the present invention, insulating foam having facing has been shown to perform better than foam without facing. Preferably, a facing is used that has increased vapor impermeability, such as a polymeric film.
To make a panel 10, the insulating material 12 is formed into a desired shape and thickness. As used in the present disclosure, “shape” refers to the two-dimensional outline of a component. For example, the insulating material 12 may have the shape of a rectangle and a thickness of two inches or more. See
One or more attachment grooves 14 are cut, such as by a hot knife, into the insulating material 12. The attachment grooves are shaped so that when concrete hardens in them the concrete is prevented from being pulled out of the groove because the foam acts as a physical barrier to block it. In other words, the maximum width of the portion of the attachment groove 14 that extends into the insulating material 12 is wider than the opening of the attachment groove 14 on the surface of the insulating material 12. In the preferred embodiment, at least part of the attachment groove 14 has a substantially triangular cross-section, as shown in
Preferably there are at least two attachment grooves 14 per segment 13 of insulation material 12. The attachment grooves 14 may run parallel or perpendicular to the structure foundation, but preferably are perpendicular to it. In an alternative embodiment, attachment perforations 15 are made in the foam panel. See
The edges 16 of the insulating material 12, including the edges 16 of any individual segments 13, are preferably squared off to provide a smooth contact surface when separate pieces of insulating material 12, or separate segments 13, are laid next to each other. See
Casting
Referring to
In one embodiment, shown in
Once the insulating material 12 and any spacing material 32 is in place within the concrete form 31, wet concrete 11 is poured into the concrete form 31 on top of the insulating material 12. The wet concrete 11 fills the attachment grooves 14 and any attachment perforations 15. See
Referring to
When the concrete 11 cures, the panel 10 is finished. The interior surface 41 of the panel 10 is concrete 11 and the exterior surface 42, which faces away from the structure, is insulating material 12.
Erecting
Once cured, the panel 10 is tilted up, by means known in the art, and set in place in the structure. In one embodiment, the panel 10 is a complete wall which is moved into place and then fastened to other walls in the structure. In another embodiment, the panel 10 is part of a complete wall which comprises more than one panel 10. In this embodiment, each panel 10 is set in place and fastened to adjacent panels 10.
A joint 50 is formed at each intersection of panels 10. The procedure of fastening panels 10 together at each joint 50 may depend on how each panel 10 is cast. If a panel 10 is cast without a spacing material 32, the concrete 11 will be flush with the insulating material 12 at each edge of the panel 10, as shown in
As shown in
Once the panels 10 are secured in place, the exterior surface 42 of each panel 10 may be coated in a finishing material. The finishing material (not shown) may be any material which is used to create the desired appearance of the structure from the outside, and which will not degrade the insulating material 12. Examples include house paint, stucco, shotcrete or other pneumatic concrete, and Gunite®. If an insulating material 12 having a facing was used, it may be necessary to remove the facing on the exterior surface 42 in order to apply the finishing material.
Example Panel Set—Low Income Housing
Referring to
By limiting the panels 10a-d to four shapes, the panels may be quickly mass-produced. Only four shapes of insulating material 12 and four concrete forms 31 are needed. The insulating material 12, concrete forms 31, concrete 11, and other required building materials may be transported to and stored at the subdivision construction site. Labor is greatly reduced during production of the panels 10a-d because no customizing is necessary. Further, wall assembly workers will be able to follow a uniform assembly process for each home. As a result, effectively insulated homes may be produced at a lower overall cost in time, labor and materials.
While there has been illustrated and described what is at present considered to be the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made and equivalents may be substituted for elements thereof without departing from the true scope of the invention. Therefore, it is intended that this invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims
1. An insulated tilt-up wall panel comprising:
- a. an insulating material;
- b. one or more attachment grooves formed in the insulating material; and
- c. concrete attached to the insulating material by the attachment grooves.
2. The insulated tilt-up wall panel of claim 1 wherein the insulating material has substantially the same shape and perimeter as the concrete.
3. The insulated tilt-up wall panel of claim 1 wherein the insulating material has substantially the same shape as the concrete and a shorter perimeter than the concrete.
4. The insulated tilt-up wall panel of claim 1 wherein the insulating material comprises a plurality of adjacent segments.
5. The insulated tilt-up wall panel of claim 4 wherein the insulating material further comprises an insulating filler, attached to the interior surface of the insulating material, which covers a seam between two adjacent segments.
6. The insulated tilt-up wall panel of claim 5 wherein the insulating filler is expanding foam glue.
7. The insulated tilt-up wall panel of claim 1wherein the insulating material comprises an interior surface and an exterior surface and the attachment grooves are formed on the interior surface of the insulating material.
8. The insulated tilt-up wall panel of claim 7 wherein each attachment groove is narrower at the interior surface of the insulating material than the groove is inside the insulation material.
9. The insulated tilt-up wall panel of claim 8, wherein at least a portion of the attachment groove has a substantially triangular cross section.
10. The insulated tilt-up wall panel of claim 1 further comprising a reinforcement structure.
11. The insulated tilt-up wall panel of claim 10 wherein the reinforcement structure comprises rebar.
12. A method of making an insulated tilt-up wall panel, the method comprising:
- a. forming an insulating material into a desired shape;
- b. forming one or more attachment grooves in the insulating material;
- c. placing the insulating material onto a substantially horizontal casting surface and within a concrete form such that the opening of the attachment grooves faces up; and
- d. pouring a desired amount of concrete into the concrete form, wherein the concrete substantially fills the attachment grooves and is attached to the insulating material when it cures.
13. The method of claim 12 wherein the insulating material comprises a plurality of segments, and forming the insulating material into a desired shape comprises:
- a. arranging the segments into a desired shape; and
- b. attaching each segment to one or more adjacent segments.
14. The method of claim 12 further comprising positioning one or more reinforcement structures within the concrete form.
15. A method of building a structure at a construction site using the tilt-up wall panel of claim 1, the method comprising:
- a. placing a plurality of tilt-up wall panels in a desired location such that the exterior surface of the insulating material of each panel is substantially vertical, and each panel forms a joint with at least one other panel;
- b. at each joint, permanently attaching the tilt-up wall panels to each other;
- c. sealing a seam between the insulating material of adjacent panels; and
- d. applying a finishing material to the exterior surfaces of the insulating material of each panel.
16. The method of claim 15 further comprising covering each joint with an insulating insert.
17. The method of claim 16 wherein permanently attaching the tilt-up wall panels forming the joint to each other comprises welding one or more stainless steel fasteners to one or more stainless steel welding posts protruding from the concrete in each tilt-up wall panel.
18. A set of insulated tilt-up wall panels for building a residential structure, the set comprising:
- a. a standard panel;
- b. a jamb panel;
- c. a lintel panel; and
- d. a sill panel;
- wherein each panel comprises: i. an insulating material; ii. one or more attachment grooves formed in the insulating material; and iii. concrete attached to the insulating material by the attachment grooves.
19. The set of insulated tilt-up wall panels of claim 18 wherein the standard panel, lintel panel, and sill panel are substantially rectangular and the jamb panel is substantially L-shaped.
20. A method of building a plurality of residential structures using the set of insulated tilt-up wall panels of claim 19, the method comprising:
- a. placing a plurality of each of the standard panels, the jamb panels, the lintel panels, and the sill panels in desired locations such that the insulating material of each panel forms a substantially vertical exterior surface, and each panel forms a joint with at least one other panel; and
- b. at each joint, permanently attaching the panels to each other.
Type: Application
Filed: Jun 25, 2008
Publication Date: Dec 25, 2008
Inventor: Daniel Chouinard (Fountain Hills, AZ)
Application Number: 12/215,185
International Classification: E04B 2/00 (20060101);