Patent Publication Number: US-7216462-B2

Title: Insulated concrete panel billets

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   None. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   This invention relates to concrete panel construction and in particular to insulating foam billets used in the manufacture of finished concrete panels. 
   The assignee of this invention owns U.S. patent application Ser. No. 10/391,081 filed Mar. 17, 2003 (F02.2-11001US01) which relates to a method for casting hollow core concrete panels in which the hollow cores are made by the use of foam billets held in place during the pours by using a raft connector, the disclosure of which is incorporated herein by reference. Extruders are eliminated via the invention herein. This represents the only hollow core concrete panel which may include cast in openings. That invention is an improvement over U.S. patent application Ser. No. 10/289,819 filed Nov. 7, 2002 (F02.2-10233US02) by the same owner, the disclosure of which is also incorporated herein by reference. 
   The pending applications of applicant referred to above work very well. However, it is desirable to form concrete panels which would have a higher insulating R value. This invention provides foam billets which provide for the manufacture of higher R value concrete panels. 
   The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. § 1.56(a) exists. 
   BRIEF SUMMARY OF THE INVENTION 
   The invention provides pre-molded foam billets that may be set in place to cover most of the panel such that the casting process of manufacturing concrete panels may result in an increased R value product while keeping manufacturing costs down and preventing flotation of the foam billets. The foam billets of the invention are designed with a plurality of spaced through holes and edge modifications are provided in the foam billets to ensure that an interlock between the lower and upper layers of concrete is made. 
   Alternatively, it has been found that the prior foam billets as described in the pending applications may be used along with a plurality of spaced drop-in foam billet joints which increases the R value and maintains the needed concrete bonding between layers. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A detailed description of the invention is hereafter described with specific reference being made to the drawings in which: 
       FIG. 1  is a perspective view of a molded foam billet of the invention; 
       FIG. 2  is a mirror image of the molded foam billet of the invention of  FIG. 1  to show the appearance of the bottom side; 
       FIG. 3  is a perspective view showing the molded foam billet of the invention of  FIG. 1  in a casting bed with concrete encasing the billet and portions left uncovered; 
       FIG. 4  is a foam billet variant to  FIG. 1 ; 
       FIG. 5  is a view similar to that of  FIG. 3  using the billets of  FIG. 4 ; and 
       FIG. 6  is a perspective view of the standard foam billets used in connection with drop-in foam billet joints. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to the Figures, the inventive foam billets to manufacture concrete slabs, panels or planks of the invention are formed with a standard concrete casting apparatus as shown in U.S. Pat. Nos. 3,217,375; 3,523,343; 4,004,874; 4,289,293 and 4,457,682, the disclosures of which are incorporated herein by reference. Basically, as shown in  FIG. 3 , such apparatus  10  include a casting bed  12  that is either stationary or is driven along rails. The casting bed  12  has a bottom pallet  14  and side walls  16 ,  18 . A concrete dispensing hopper can be of any of the current hoppers used to distribute concrete onto a moving bed. Alternatively, the hopper may move relative to a stationary bed. Lower and upper prestressed cables,  22 ,  24 , respectively, are positioned along the length of the bed  12 . 
   In operation, as, shown in  FIGS. 3 ,  5  and  6 , a first layer of concrete  30  is cast with a very fluid mix called “self-compacting concrete” in the industry. This concrete does not require a screed step. Conventional foam billets  40  which are generally rectangular in shape are shown in  FIG. 6 . This view is similar to that in applicant&#39;s previous applications with the exception of additional drop-in fill joint billet blocks  42  which are placed against the casting bed side walls  16 ,  18  as shown and between each billet  40 . 
   The billet blocks  42  are spaced from one another to ensure that concrete from the lower layer  30  may bond to the upper concrete layer  32 . In addition, the drop-ins  42  are desirably placed at every billet joint. Therefore, if each billet is  8  feet in length, a billet block  42  should be at least every 8 feet. In addition, it is preferred that the billet joints are staggered and that no more than three billet blocks  42  are lined up across the width of the panel. A typical billet block  42  may be about  16  inches in length for ease of handling and insertion. Space  44  is left between each succeeding billet block  42  for concrete bonding. 
   The billets  40  are held to the concrete by any mechanical connections such as wire tied rebar that may be placed over and across the width of the bed and tied to cable  24 . It has been found that a substantial holding force is generated simply by the placement of foam onto the lower wet concrete. Finally, the top layer of concrete  32  is cast which is a traditional concrete mix. Any additional insulating sheets are placed on top of the structural section. 
     FIGS. 1 through 5  show that a premolded billet  50  may be used in the casting beds  12  which are formed with sides  52 ,  54  which have staggered projections  56  such that insulation is provided along the edges of the finished concrete panel yet gaps are provided to provide the required bonding of concrete layers. The internal body of the premolded billets  50  may have a plurality of staggered concrete bonding openings  60  as shown. The lower concrete  30  is able to bond to the upper layer of concrete  32  through openings  32 . It may also be desirable to mold premolded billets  50  to include partial channels  62  which are spaced to fit around the prestressed cables  22 ,  24 . Note that the premolded billets  50  of the FIGS. are shown with three main sections  64  separated by two channels  62 . This is for simplicity. In a standard eight foot wide panel a total of six main sections  64  may be employed along with seven channels  62 . This will vary depending on the width of the panel and the spacing and number of prestressing cables  22 ,  24 . 
   Note that to keep the desired spacing of staggered edges and openings that a premolded billet  50  of  FIG. 1  is followed by its mirror image, a flipped over premolded billet  50  of  FIG. 2 , and vice versa. This ensures that maximum coverage of the finished concrete panel with insulating billet material will occur while keeping the required bonding between the lower and upper concrete layers. 
     FIGS. 4 and 5  show a premolded billet  50  having main sections  64  and channels  62 . However, it also depicts that cable channels  70  may be formed within channels  62  to better locate the premolded billets  50  to the casting bed by forming guides to the prestressed cables  22 ,  24 . 
   When used herein, the term “foam billets” refers to billets of any material that become an integral member of the finished panel. Where billets is used herein, it refers to foam billets but also to any shape holding structure that may be placed in the bed to form a void for the hollow core panels to be formed. 
   While this invention may be embodied in many different forms, there are shown in the drawings and described in detail herein specific preferred embodiments of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. 
   The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims. 
   This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.