Patent Publication Number: US-6338231-B1

Title: Prefabricated concrete wall panel system and method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to the field of construction and, more particularly, to a precast concrete wall panel and a wall system using such panels. 
     2. Description of the Related Art 
     Modular wall panels and wall systems disclosed in the prior art include the two-slab system of U.S. Pat. No. 2,882,712 to Carlson, the slab-shaped block system with locking rail of U.S. Pat. No. 3,435,581 to Ahlqvist, the prefabricated juxtaposable elements joined with injected settable binder of U.S. Pat. No. 4,015,387 to Tillie, and the prefabricated modular room elements of U.S. Pat. No. 4,228,623 to Menosso. The prior art, however, does not teach a precast unitary concrete wall panel having the structural strength and inside-wall finishing convenience taught by the present invention. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a precast concrete wall panel structure which includes a rectangular concrete frame having a flat side and a recessed side. Preferably, the concrete is reinforced with polypropylene fibers. On the perimeter of the frame and along the face of the recessed side, concrete ribs are cast for stiffness and strength, such as when handling the panel. The recessed side is filled with an insulation batt. A strip of wood molding is provided on each longitudinal edge of the frame on the recessed side. This wood molding provides a convenient attaching means for fastening dry wall to the concrete wall panel structure when finishing the inside wall surface. 
     The present invention also encompasses a precast concrete wall panel system using the precast concrete wall panels of the present invention. More specifically, a wall is formed by placing the panels vertically in side-by-side relation on a foundation and concrete is then poured into a vertical cavity formed by a recess in the adjacent side edges of the panels to unite them. Vertically extending reinforcement bars have one end embedded in the foundation and are horizontally spaced to coincide with the poured concrete panel joints. The reinforcement bars anchor the panels to the foundation as well as to the roof, and provides rigidity against any horizontal force acting against the wall. The panels are complemented with other precast concrete components including those necessary to form wall corners, window frames and door frames. 
     In view of the foregoing, one object of the present invention is to provide a precast concrete wall panel having interior-facing wood moldings for easily fastening a vapor barrier and drywall to the inside face of the wall panel. 
     Another object of the invention is to provide a precast concrete panel embedded with an insulation batt. 
     A further object of the invention is to provide a wall panel in accordance with the preceding objects having significant strength, being made of concrete reinforced with polypropylene fibers. 
     A still further object of the invention is to provide a concrete wall panel having concrete ribs for enhanced stiffness and strength, such as during handling. 
     Still another object of the invention is to provide a concrete wall panel frame having longitudinal recesses on each side face such that, when the frames are placed side by side, channels are formed therebetween to receive reinforcement bars and poured concrete. 
     It is yet another object of the invention to provide a precast unitary wall panel that is not complex in structure and which can be manufactured at low cost but yet efficiently. 
     These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a precast unitary concrete panel with insulation batt in accordance with the present invention; 
     FIG. 2 is a front elevational view of the inner surface of the panel shown in FIG. 1; 
     FIG. 3 is a side elevational view of the panel shown in FIG. 1; 
     FIG. 4 is an elevational cross-section view along line  4 — 4  of FIG. 2; 
     FIG. 5 is an enlarged view of area W showing the details of a lower corner of the panel shown in FIG. 1; 
     FIG. 6 is an enlarged view of area X showing the details of an upper corner of the panel shown in FIG. 1, together with reinforcement bar positioned in accordance with the present invention; 
     FIG. 7 is a rear perspective view of the preferred insulation batt of FIG. 1 showing the cutouts which form the reinforcing ribs of the concrete panel; 
     FIG. 8 is a cross-sectional view showing two panels joined in side-by-side relation for forming a wall in accordance with the present invention; 
     FIG. 9 is a top view of a corner component joined with two wall panels in a first assembly according to the present invention; 
     FIG. 10 is a top view of the corner component of FIG. 9, joined with two wall panels in a second assembly according to the present invention; and 
     FIG. 11 is a top view of a spacer wall component in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Although only one preferred embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Also, in describing the preferred embodiment, specific terminology will be resorted to for the sake of clarity. It is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. 
     Referring now more specifically to the drawings, FIGS. 1 and 2 illustrate the preferred precast concrete wall panel structure, generally designated by the reference numeral  10 , of the present invention. FIG. 3 shows a vertical side view of the wall panel structure  10 , and FIG. 4 is a vertical section view along line  4 — 4  of FIG.  2 . 
     The wall panel structure  10  includes an essentially rectangular concrete frame  20  having an upper header  22 , a footer  24 , a flat outside face  26 , a recessed inside face  28 , and two side faces generally designated by the reference numeral  30 . The recessed inside face  28  includes on its surface a plurality of ribs  32  which preferably extend generally horizontally across panel  10  and are vertically spaced. An eight foot high panel structure  10  typically has three horizontal reinforcing ribs  32 . The recess within the inside face is filled with an insulation batt, generally designated by the reference numeral  34 . 
     In the preferred embodiment, the thickness of the frame between the flat outside face  26  and that portion of the recessed inside face  28  from which the ribs  32  extend is approximately one and a half inches. The batt  34  has a thickness of approximately three inches. These thicknesses may be adjusted as necessary or desired to accommodate particular construction requirements. 
     The frame  20  is constructed with concrete or other cementitious mixture. In the preferred embodiment, the concrete used to construct the frame has a strength of f′c=3000 psi and is reinforced with standard polypropylene fibers. The polypropylene fibers prevent cracks during the settling of the concrete when poured. Materials other than polypropylene fiber, e.g., wire mesh, may additionally or alternatively be used to reinforce the concrete, as would be known to persons of skill in the art. 
     The wall panel structure  10  includes wood molding  36  along the longitudinal edges on both sides of the recessed inside face  28 . The wood molding  36  has an exposed side face  36   a  and an exposed front face  36   b . The lower ends of the wood molding  36  preferably rest upon the footer  24 . The flat outside face  26  of the concrete frame  20  has longitudinal edges  38  which extend laterally to be roughly flush with the exposed side face  36   a  of the wood molding  36 , leaving a side edge recess  40 , running longitudinally, in the center area of each side face  30  of the frame  20 . In addition to forming the side edge recess  40  with the wood moldings  36 , the concrete longitudinal edges  38  act as reinforcement ribs along the side perimeters of the frame  20  for increased strength and stiffness. 
     The footer  24  of the concrete frame  20  also has a side face  42  which includes a further recess  44  to accommodate reinforcement rods or bars, i.e., rebar, or other structural members used to secure the wall panel in place on a foundation. FIG. 5 illustrates an enlarged view of the lower end portion of the frame  20  including footer  24 . As shown, the wood molding  36  rests upon the top of the footer  24 . The footer  24  includes side face  42  with recess  44 . The longitudinal recess  40  in the side face  30  of the frame  20  is vertically aligned with the recess  44 . It will also be seen that longitudinal edge  38  has a tapered surface  45  opposite flat outside face  26  which facilitates formation of the edge  38  and removal from the forming mold. 
     FIG. 6 illustrates an enlarged view of the upper end portion of the frame  20  including header  22 . As shown, the wood molding  36  is secured to the recessed inside face  28  of the frame  20 . The longitudinal recess  40  in the side face  30  of the frame  20  accommodates rebar  50  which extends vertically from the foundation, through the recess  44  in the footer  24 . The rebar may extend through only part of the vertical height of the wall panel or may extend upwardly beyond the upper header  22 , depending on building requirements. 
     The insulation batt  34  is shown in FIG.  7 . As shown, the insulation batt  34  is preferably comprised of four small batts  59 , each of approximately the same size and shape. Each batt  59  has a lip  57  on two planar longitudinal edges. When the batts  59  are stacked one upon another, the lips  57  of adjacent batts abut, creating a channel  60  between each pair of adjoining batts  59 . When the frame is cast around the insulation batt  34 , the channels  60  serve to form the ribs  32  on the recessed inside face  28  of the frame. While the use of four small bats  59  make the insulation batt  34  easier to handle and to set in place during fabrication of the panel, the insulation batt  34  could have a unitary construction or be comprised of different numbers of smaller batts. 
     The insulation batt  34  has an inner face  56  which is in contact with the recessed inside face  28  of concrete frame  20 , and an outer face  58  which is generally flush with the front surfaces of the wood molding strips  36  (see FIGS.  1  and  4 ). In addition to providing insulation properties to the wall panel structure  10 , the insulation batt  34  operates as an inner mold for defining the recessed inside face  28  of the concrete frame  20 , as well as inside surfaces for the side faces  30 , the upper header  22 , and the footer  24  of the frame  20 . Once the panel is cast, the batt operates as a “lost” mold, being contained within the frame and molding. Integration of the wood, concrete and insulation components of the panel into a unitary structure may therefore be accomplished in a single operation. 
     In the preferred embodiment, the insulation batt is made of mineral wool and is approximately three inches thick. As would be known by one of skill in the art, this choice of material and thickness may vary in accordance with necessary or desired final frame construction characteristics. 
     The wall panels  10  are joined together as shown in FIG.  8 . The longitudinal edges  38  of the flat outside faces  26  of adjoining wall panel structures  10  abut one another to create an outside joint  46 . Silicon or other sealing material is preferably used to fill the outside joint  46 . The strips of wood molding  36  along the longitudinal edges of recessed inside faces  28  of the two adjoining panels  10  also abut one another on their exposed side faces  36   a  to create an inside joint  48 . In the preferred embodiment, cork is used to effectively fill and seal the inside joint  48 . 
     During construction of a concrete foundation upon which the panels of the present invention are to be mounted, boards of an appropriate size, such as a 2×4, are embedded in the top surface of the foundation. The reinforcement rods or bars  50 , often called rebar, are also embedded in the concrete of the building foundation in those places where the panel joints  46 ,  48  will be located. When the boards, e.g., 2×4&#39;s, are later removed, a recessed area is created. This recessed area provides a place to set the lower end of a panel  10  of the present invention when locating the panel  10  on the concrete foundation. The recess also prevents rain water from penetrating underneath the panels and into the house. The plumb of the wall is established and maintained by means of wall braces in the conventional way. Once the panels  10  have been set and joined upon the foundation in the manner shown in FIG. 8, a hollow channel or key  52  is formed by the side edge recesses  40  of the adjoining concrete frames  20 . Cement mortar is then poured into the key  52  to prevent movement of the adjoining frames. The cement-filled keys  52  with reinforcement rods  50  embedded therein make the wall monolithic, anchoring the wall to the foundation and providing rigidity against any horizontal force acting against the wall. The reinforcement bars  50  may additionally extend upward to anchor the wall to the roof as well. The front faces  36   b  of the wood moldings  36  then provide a convenient and effective attaching means for fastening a vapor barrier (not shown) and any type of drywall  54  to the wall panel  10  to create an attractive inside finish. 
     The wall panel of the present invention as has been described is complemented with other components such as corners, door frames, window frames, etc. FIG. 9 is a top view of a corner component  62  abutting the longitudinal edges  38  of two wall panels at outside joints  46 . Corner components  62  are approximately square in cross section, having a depth and a width that correspond to a depth of the wall panels. Each corner component  62  is constructed of precast concrete and has a longitudinal channel  68  generally in the center thereof, and preferably circular, which runs the height of the component  62 , through which rebar  50  may extend. Although not shown, corner components may be constructed by stacking and/or arranging suitably shaped blocks adjacent one another to the desired dimensions. Alternatively, each corner component may be constructed from two full-length halves, each having a semi-circular recess which, when placed adjacent another half, forms the longitudinal channel  68 ; the halves are then joined by pouring concrete to fill the longitudinal channel  68 . The corner components may also be constructed in full-length quarters, or other divisions, constructed to form a longitudinal channel  68  when joined together. 
     The corner component  62  as shown in FIG. 9 has two outer wall surfaces  64 . A wood molding  66  is recessed into one corner of the corner component  62  and abuts the wood molding  36  of each wall panel at joints  48 . Channel  68  and keys  52  formed between the corner component  62  and the wall panels are filled with cement mortar to form a rigid corner when the cement mortar hardens. Drywall panels  54  then can be conveniently mounted on wood moldings  36 , with or without a vapor barrier, by conventional means such as nails or staples. 
     FIG. 10 is a top view of corner component  62  joined with two wall panels in a second assembly. As shown, the corner component  62  has two wall surfaces  70  flush with molding  66 . The longitudinal edges  38  of the two wall panels  10  join corner component  62  at joints  46 . The wood molding  66  of the corner component  62  is used to attach the drywall  54  to the corner component  62 . The wood molding  36  of the wall panels also supports the dry wall  54  and abuts the corner component  62  at joints  72 . Keys  52  formed between the corner component  62  and the wall panels  10 , as well as the longitudinal channel  68 , are filled with hardenable cement mortar. 
     FIG. 11 illustrates a top view of a spacer wall component, generally designated by the reference numeral  74 . Like the wall panels, the spacer wall component  74  has a flat outside face  26  with longitudinal edges  38 , and a recessed inside face  28  which receives batt  34 . The width of the frame is reduced, however, to enable the spacer wall component to be used to complete spaces in the wall system where there is insufficient space for the standard wall panel. 
     In accordance with a preferred method of construction, the exact location of each panel is determined at the outset and the vertical rebar is set in the foundation at the requisite spaced locations in the keys of adjoining panels. To construct the walls, the corner components are set first, with wall panels being added in sequence, moving toward the center of each wall. Each panel is set in the recessed area created in the foundation by the framing boards and plumbed with wall braces. The mortar is then poured into the keys; once the mortar has hardened, the wall braces are removed. 
     The wall panels of the present invention are suitable for the construction of exterior walls of houses and all sorts of other buildings. The outside surface, embodied as the flat outside face  26 , is preferably plain concrete with a floating texture. Other textures are of course possible. The inside finish of the wall is independent of the panel and is formed, preferably with a vapor barrier, and with any type of drywall, both of which are fastened to the wood moldings. 
     The foregoing descriptions and drawings should be considered as illustrative only of the principles of the invention. The invention may be configured in a variety of shapes and sizes and is not limited by the dimensions of the preferred embodiment. Numerous applications of the present invention will readily occur to those skilled in the art. Therefore, it is not desired to limit the invention to the specific examples disclosed or the exact construction and operation shown and described. Rather, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.