Abstract:
A block-out tube for use in joining together pre-cast concrete members, the block-out tube having an ovalized cross-section, an integral elongate imperforate hollow tubular body with smoothly curved corrugated walls, a rounded tip closing the bottom end thereof, a mounting flange with tear-away nail tabs at the top open end thereof, and a removable transparent member for sealing the top end for preventing water and debris from entering the interior of the tube. The block-out tube, secured by attaching the tear-away tabs to a concrete pouring form, is cast into the top of the lower concrete member, the ovalized corrugated body being embedded therein and the top sealed end being exposed at the top surface thereof, after the removal of the form. When the concrete members are erected and joined, the transparent sealing means at the top end is removed, the block-out tube is filled with grout, and a structural rod extending outwardly from one member is fitted into the grout-filled tube as the one member is joined to the other member, the grout engaging the structural rod and the corrugated tube wall, forming a strong joint between the two concrete members.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates generally to connection devices for joining together pre-cast concrete members such as panels or columns stacked one on top of the other to form building walls, the connection devices employing a grouted connection between a block-out tube cast into the top of a lower concrete member and a structural rod cast into the bottom of an upper concrete member. More particularly, the present invention relates to an ovalized block-out tube that provides structural strength, in addition to a tolerance for misalignment with the structural rod, when the upper panel is assembled onto the lower panel. 
   Conventional connections for joining cast concrete wall panels use metal spiral tube sections cast into the top of the lower panel. These block-out tube sections are mounted on a framing member in the form used to cast the panel, oriented inwardly in the center of the top wall of the panel. Tape is used to close the bottom of the spiral tube sections. After pouring of the concrete panel and setting of the concrete, the forms are removed and the open ends of the tubes are sealed or taped, or alternatively a plug is driven into each tube. 
   A lower panel with conventional spiral tubes cast in place is erected and the tubes are opened and filled with grout or mortar. An upper panel with structural rods aligned with the tubes and extending downwardly from the lower surface of the panel is lowered onto shims with the rods extending into the grout placed in the opened tubes. The grout sets to form a joint between the two panels. 
   It is difficult to secure the spiral tube used in the conventional joint to the forms used for pouring a lower panel. The taped seal at the inner end of the tube may leak allowing concrete to flow into the interior of the tube during the casting of the lower panel. The tape and plug seals used to close the tube sections are ineffective and frequently allow water, moisture, and dirt to collect in the tubes prior to the erection of the panels. If the water in the tube freezes there is a risk that resultant expansion will crack and ruin the panel. Any debris collected within the tube will degrade the quality of the connection formed by the mortar when the panels are erected. The sharp corner in the concrete at the bottom of the tube concentrates stress in the cast panel and can lead to cracking of the panel. 
   In addition, the circular cross-section of the spiral tubes is not much larger in diameter than the structural rods which are mortared therein, and thus do not allow any appreciable tolerance for misalignment of the respective connection devices of the two panels. Often concrete panels are joined by multiple sets of tubes, spaced along the length of top surface of the lower panel, and rods, spaced along the bottom surface of the upper panel. If there is slight variation in the spacing of the tubes as compared with the spacing of the rods, assembly of the two panels becomes very difficult if not impossible. 
   An improvement to the conventional connection apparatus is disclosed in U.S. Pat. No. 5,134,828 [Baur] that discloses a closed-end blow molded tube for use as the block-out in a pre-cast lower panel. While this device overcomes some of the problems existing in the conventional connection device as described previously, it leaves some disadvantages unaddressed and further introduces new disadvantages. This device nicely solves the problem of keeping water, moisture, and debris from entering the block-out tube before, during, and after pouring of the concrete panel. However, this device is nominally circular in cross-section and straight-sided along its length, and therefore includes a series of recesses to engage the surrounding concrete and the internal grout. Engagement of the tube recesses with the concrete and the grout gives the device the structural strength important for joining the lower panel to an upper panel, but also creates areas of stress concentration in the pre-cast concrete panel that may increase the tendency of the concrete panel to crack. Additionally, the circular cross-section is the same as that used in the conventional spiral tube and therefore does not provide for any additional tolerance for misalignment of tubes and rods along the length of the two mating concrete panels. As a further minor inconvenience, this device is nailed to the concrete pouring forms and when the forms are removed, the nails are left sticking outwardly from the concrete panel with the nail heads trapped between the tube mounting flange and the concrete. 
   Accordingly, it is an object of the present invention to provide a block-out tube for use in joining pre-cast vertical concrete panels that provides structural strength without introducing stress concentrations into the poured concrete or grout. It is another object of the present invention to provide a block-out tube that prevents the entry of water, moisture, or debris that could degrade the quality of the grout connection inside the tube. 
   It is yet another object of the present invention to provide a block-out tube which may be separated from the concrete pouring form without leaving exposed nails protruding from the finished concrete panel. It is a further object of the present invention to provide a block-out tube which accommodates for minor misalignments of spacing and positioning between the tubes along the length of the lower concrete panel into which the tubes are cast and the structural rods along the length of the mating upper concrete panel into which the rods are cast. 
   Other objects will appear hereinafter. 
   SUMMARY OF THE INVENTION 
   The present invention overcomes the disadvantages inherent in the types of devices known in the prior art for joining vertical pre-cast concrete panels. While the disclosure herein refers to joining of pre-cast concrete panels, it is understood that the present invention may be used to join columns and other types of pre-cast concrete members. 
   The present invention comprises a tube of ovalized cross-section, which is non-cylindrical, and an elongate body corrugated with a series of periodic undulations. This tube is molded as an imperforate monolithic piece and is smooth along its length, with no sharp corners or edges. The tube includes a rounded tip at one end and a flange with tear-away tabs extended outwardly around the perimeter of the opposite open end. The open end of the tube is covered over with a waterproof transparent sheet, adhered to or molded onto the flange. 
   The tube of the present invention is intended to be cast vertically into the top side of a lower concrete panel with the covered flanged end facing upwardly and the elongate body with the rounded tip embedded in the panel. Once the concrete has set, the ovalized (or non-cylindrical) cross-section of the tube keeps it secure from rotating in the concrete panel and the corrugations along the length of the tube give it high pullout strength. Because of the gentle corrugations formed by the large radius undulations in the walls of the tube, as well as the rounded tube tip, no significant stress concentrations are introduced into the concrete panel by the presence of the tube. 
   For joining the lower concrete panel to an upper concrete panel having structural rods extending downwardly from the lower side thereof, the tubes are filled with grout or mortar and the upper panel is lowered onto the lower panel with the structural rods becoming embedded in the grout within the internal cavities of the tubes. The ovalized shape and corrugated walls of the tube provide structural strength to prevent the grout from rotating or pulling out from within the tube, as the grout engages the roughened surface of the structural rod to form a strong connection between the lower panel and the upper panel. 
   The transparent cover sheet over the open flanged end of the tube serves to prevent water or dirt from entering the tube during the molding of the concrete panel and during the interval between the molding and the erection of the panel when the panel may be stored onsite or in a warehouse for a considerable period of time. The transparency of the cover sheet permits visual inspection of the interior of the tube prior to erection and joining of the concrete panels to ensure that water, moisture, and debris have not entered or accumulated in the tube. At the time of erection, the cover sheet may be either removed or punctured and bent away in order to allow the filling of the tube with grout and the insertion of the structural rod. In the unlikely event that a small amount of water should seep into the interior of the tube and freeze, the curved walls and rounded tip lift the ice as it freezes, regardless of the orientation of the panel at the time, thus reducing the risk of stress cracking in the concrete. 
   Prior to the forming of the concrete panel, a number of tubes will be attached at appropriate locations to a member at the top of the panel form by nailing or fastening through the tear-away tabs on the tube flange into the form member. When the panel is poured, the concrete will encase the elongate portion of the tube with the tube flange being flush along the top side of the panel. After the concrete has set, the form may be separated from the tube by breaking the tear-away tabs off from the tube flange, leaving the embedded tube with the covered flanged end facing outwardly from the panel. The tabs and nails can then later be removed from the form member if desired. 
   The major axis of the ovalized (or non-cylindrical) cross-section of the tube, which is about fifty percent longer than either the minor axis or the diameter of the conventional or improved block-out tubes previously discussed, is oriented along the length of the concrete panel. Therefore, when two panels are joined as described previously, the tube of the present invention is capable of accommodating a greater amount of misalignment between the tubes and the corresponding structural rods than can be accommodating in prior art devices. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For the purpose of illustrating the invention, there is shown in the drawings forms which are presently preferred; it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
       FIG. 1  is a side view of the ovalized concrete block-out tube of the present invention. 
       FIG. 2  is a top plan view of the ovalized concrete block-out tube of the present invention showing the tear-away nail flanges. 
       FIG. 3  is a partially broken away side view of the ovalized block-out tube of the present invention showing the connection of two concrete forms with a structural rod centered within the tube. 
       FIG. 3A  is a top view of the ovalized block-out tube of the present invention showing the structural rod centered within the tube. 
       FIG. 4  is a partially broken away side view of the ovalized block-out tube of the present invention showing the connection of two concrete forms with an off-center structural rod within the tube. 
       FIG. 4A  is a top view of the of the ovalized block-out tube of the present invention showing the off-center structural rod within the tube. 
       FIG. 5  is a partially broken away side view of the ovalized block-out tube of the present invention showing the connection of two concrete forms with a non-ribbed structural rod within the tube. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following detailed description is of the best presently contemplated mode of carrying out the invention. The description is not intended in a limiting sense, and is made solely for the purpose of illustrating the general principles of the invention. The various features and advantages of the present invention may be more readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings. 
   Referring now to the drawings in detail, where like numerals refer to like parts or elements, there is shown in  FIG. 1  a side view of the ovalized (or non-cylindrical) block-out tube  10 . The tube  10  is comprised of a rigid corrugated ovalized elongate tubular wall  24  including a series of large-radius circumferential protrusions  14  and large-radius circumferential indentations  12  along the axial orientation thereof. The tube  10  further comprises a closed rounded tip  18  at one end thereof and an open end  26  at the opposite end thereof. The open end  26  includes an integral nail flange  16  with tear-away tabs  22 , as shown in the top view of  FIG. 2 . The tube  10  is preferably blow molded from thermoplastic resin to a relatively uniform thickness to give the wall  24  consistent strength along its length. The blow molded tube  10  is imperforate and waterproof, with the tube wall  24 , the tube tip  18 , and the flange  16  formed from one integral piece of blow molded material. 
   As shown in  FIG. 3 , the tube  10  is designed to be used in conjunction with a structural rod assembly  38  to align and secure an upper concrete panel  36  to a lower concrete panel  34  during assembly of concrete panels into a larger structure. Multiple sets of tubes  10  and rod assemblies  38  may be used to secure each pair of concrete panels  34 ,  36 . The ovalized or non-cylindrical block-out tube  10  is embedded in the concrete at the top of the lower panel  34  at the time of casting, and the upper rod portion  40  of the rod assembly  38  is embedded in the concrete at the bottom of the upper panel  36  at the time of casting with the lower rod portion  30  extended outwardly therefrom. The concrete of the lower panel  34  engages the corrugations  12 ,  14  on the outside of the wall  24  of the tube  10  to secure the tube  10  in the panel  34  with a significantly higher pullout strength than would occur without the corrugations  12 ,  14 . The large radii of the corrugations  12 ,  14 , as well as the rounded tube tip  18 , minimize the stress concentrations on the concrete panel  34  to guard against cracking. Additionally, the ovalized cross-section of the tube  10  prevents the tube  10  from turning within the concrete panel  34  without the need for circumferential recesses for concrete engagement, as may be required in block-out tube devices of generally circular cross-section. 
   Upon assembly of panels  34 ,  36 , the interior of the tube  10  is filled with the grout  32  and the lower rod portion  30  of the rod assembly  38  is inserted into the grout-filled tube  10 . The grout  32  engages the corrugations  12 ,  14  on the inside of the wall  24  of the tube  10 , and additionally engages the roughened surface  39  (shown as outward facing “dimples” arrayed along the outer surface of the rod  38 ) along the surface of the lower rod portion  30 , to form a strong connection between the two panels  34 ,  36 . As in the case of the concrete, the large radii of the corrugations  12 ,  14 , as well as the rounded tube tip  18 , minimize the stress concentrations on the grout  32  to guard against cracking. Further, the ovalized cross-section of the tube  10  prevents the grout  32  from turning within the tube  10  without the need for circumferential recesses for grout engagement, as may be required in block-out tube devices of generally circular cross-section. 
   The integral flange  16  extends outwardly from the tube  10  at the open end  26 , the flange  16  extending completely around perimeter of the end  26 . As shown in  FIG. 2 , the nail flange  16  includes tear-away nail tabs  22  at the corners thereof for removably fastening the tube  10  to a concrete pouring form. The open end  26  may be sealed closed by a transparent plastic cover sheet  20  which may be adhered to the upper surface of the flange  16  using an appropriate adhesive (not illustrated). The adhesive forms a waterproof seal between the cover sheet  20  and the flange  16  thereby closing off the interior of the tube  10  against moisture, water, and dirt. The cover sheet  20  is adhered to the flange  16  during manufacture of the tube  10 , prior to embedding the tube  10  into the lower panel  34 . Alternatively, the open end  26  may be sealed closed by a plastic sheet blow molded integrally with the tube  10 . Other types of seals may also be used. The transparency of the cover sheet  20  enables a worker, prior to assembly of the concrete panels  34 ,  36 , to visually inspect the interior of the tube  10  to ensure that it is clean and without contaminants. 
   In one embodiment, the tube  10  has a length of about 24 inches, an ovalized (or non-cylindrical) cross-section with a minor axis of about 3½ inches and a major axis of about 5 inches, and is located midway between the sides of a concrete panel having a thickness of about 12 to 18 inches, with the minor axis oriented in parallel with the panel thickness. The radius of curvature of the corrugations  12 ,  14  is about 6 inches so that the peak to trough height of the undulations of the tube wall  24  is about ½ inch. The tube  10  may be molded from a high density polyethylene or other suitable plastic resin and may have a wall thickness of about 0.080 to 0.100 inch. A waterproof adhesive seals the transparent cover sheet  20  to the upper surface of the flange  16  but not to the tear-away tabs  22 . 
   The lower panel  34  is cast conventionally, on its side, using appropriately sized wooden or metal forms, and concrete and reinforcing bars. When the forms are readied for pouring, a number of the ovalized concrete block-out tubes  10  are fastened to the form member defining the top wall of the panel, each tube  10  being fastened using finishing nails or other fasteners driven through the tear-away tabs  22  of the nailing flange  16  in order to removably hold the tube  10  in place on the side of the form. The tube  10  extends into the form and is preferably located midway between the top and the bottom of the form. 
   After the appropriate number of ovalized tubes  10  have been nailed to the form, reinforcing bars are placed in the form and concrete is flowed into the form. The concrete surrounds the tube  10  and envelopes the corrugations  12 ,  14  in the outer surface of the tube wall  24 . The imperforate construction of the tube wall  24 , the tube tip  18 , and the cover sheet  20  prevent the concrete from entering the interior of the hollow tube  10 . Further, the corrugations  12 ,  14  stiffen the tube wall  24  and prevent the pressure of the liquid concrete flowed into the mold from crushing the tube  10 . This pressure, depending upon the depth of the tube  10  in the mold, may be as great as 450 pounds per square inch. 
   After the concrete in the form has set to make the panel, the top wall form is stripped away from the panel  34  by pulling off the tear-away tabs  22  from the flange  16 , leaving the cover sheet  20  bonded to the flange  16  and exposed on the top wall of the panel  34 . The upper panel  36  may be similarly formed with the upper rod portion  40  of the rod assembly  38  embedded in the panel  36  and the lower rod portion  30  extending outwardly from the bottom side of the upper panel  36  after the concrete pouring form is removed. Both cast panels may be stored at the manufacturing site or shipped to the job site as required. 
   Following the casting of the lower panel  34 , the flanged ends  26  of the tubes  10  remain sealed by the cover sheets  20  to prevent water, moisture, or debris from entering the interior thereof. Preventing water from entering the tube  10  is particularly important because water collected in the tube  10 , when frozen, expands and could crack and ruin the panel  34 . Debris or moisture collected within the tube  10  could prevent the grout  32  from forming a proper joint with the tube  10 . The cover sheet  20  is transparent to serve as a window to permit visual inspection of the interior of the tube  10  to ensure that it has remained empty and clean during the time interval between casting of the panel  34  and opening the cover sheet  20  to receive the grout  32  when the lower panel  34  is erected and joined to the upper panel  36 . 
   At the time of erection with the lower panel  34  positioned vertically with the cast-in-place block-out tubes  10  facing upwardly and opening on the top wall of the lower panel  34 , a worker first visually inspects the interior of the tubes  10 , and finding the interiors to be clean and empty, the worker then removes the cover sheets  20 . A cover sheet  20  may be removed physically by first puncturing the sheet  20  and then tearing the sheet  20  away from the flange  16 . In a tube  10  sealed closed by an integral cover sheet  20 , the cover sheet  20  may be burned off using a torch commonly used and available when erecting concrete structures. Alternatively, the cover sheet  20 , whether integral or adhered to the flange  16 , may be cut away, or in some circumstances, ruptured and bent down into the interior of the tube  10 . 
   Opening the cover sheet  20  may injure the tube wall  24  cast in the concrete panel. Such injury is incidental to the operation of the tube  10  since once the cover sheet  20  is removed to open the interior of the tube  10  there is no longer a need to maintain a sealed interior. After the tube  10  is opened, the grout mixture  32  is poured into the open tube  10  and fills the interior thereof. The upper panel  36  is positioned vertically above the lower panel  34  with the lower rod portions  30  extending downwardly, with each lower rod portion  30  positioned above a block-out tube  10 . Shim plates  42 , which may be ½ inch thick plates measuring six inches on a side, are place on the upper surface of the lower panel  34  at appropriate locations. The upper panel  36  is carefully lowered down on top of the lower panel  34  so that each lower rod portion  30  extends down into a grout-filled tube  10  until the upper panel  36  rests in place on the shims  42  on the lower panel  34 . 
   The grout  32  is then allowed to harden in order to form a strong, rigid connection between the two panels  34 ,  36 . Grout extends into the corrugations  12 ,  14  on the interior of the walls  24  of the tubes  10  to form connections with the lower panel  34 ; the grout  32  also engages the roughened surface  39  of the lower rod portions  30  to form a strong connection with the rod assembly  38  and with the upper panel  36 . Once the grout  32  is fully set, the resulting high strength concealed joints between the panels  34 ,  36  are completely confined within the thickness of the panels and do not project beyond the panel side walls. If desired, the horizontal space between the panels  34 ,  36  and the shims  42  may be caulked or pointed. 
   During assembly of the upper panel  36  onto the lower panel  34 , it is possible that some of the multiple pairs of rod assemblies  38  and block-out tubes  10  may not be perfectly aligned along the length of the panels  34 ,  36 . Since the major axis of the ovalized tubes  10  is positioned parallel to the length of the panels  34 ,  36 , the ovalized tube  10  of the present invention permits increased tolerance for such misalignments when compared with a block-out tube of generally circular cross-section. This clearance advantage is shown in  FIGS. 4 ,  4 A, which illustrate that the ovalized tube  10  can accommodate an off-center rod assembly  38  while retaining space for sufficient grout  32  to create a proper joint. When compared to  FIGS. 3 ,  3 A that show an axially centered lower rod section  30  within the non-cylindrical tube  10 , it becomes readily apparent that the tube  10  is structured to accommodate the misalignment of the rod  38  not only principally along the length of the concrete form, i.e. the major axis of the ovalized tube  10 , but also across the ovalized tube along the minor axis as shown in  FIG. 4A . 
   Referring to  FIG. 5 , there is shown a rod assembly  38  without the roughening of the outer surface, having relatively smooth sides. It is to be considered part of the present invention that the rod assembly  38  can have either a roughened outer surface  39 , as shown in  FIGS. 3 ,  3 A,  4 ,  4 A, or a relatively smooth outer surface, as shown in  FIG. 5 . In all other respects the depiction of the invention, its forming and assembly remain the same. 
   The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, the described embodiments are to be considered in all respects as being illustrative and not restrictive, with the scope of the invention being indicated by the appended claims, rather than the foregoing detailed description, as indicating the scope of the invention as well as all modifications which may fall within a range of equivalency which are also intended to be embraced therein.