Patent Publication Number: US-2015078822-A1

Title: Apparatus and method for joining adjacent concrete panels

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an apparatus and method by which a connecting rod which projects from one end of a first concrete panel or slab is moved into receipt and affixed inside a rod-receiving channel formed in an opposing end of an adjacent concrete panel or slab in order to form a reliable joint by which to connect the panels to one another. The apparatus and method have particular application in roadway construction and/or repair where several panels must be laid end-to-end (and/or side-by-side) and connected one to the next so as to create a continuous flat surface such as a roadway to support vehicular traffic. 
     2. Background Art 
     As new communities are built, it is essential to have a roadway system to link each community with neighboring communities. Therefore, a series of highways and freeways are constructed to support vehicular traffic. A common technique for building such roadways is to lay a number of heavy precast concrete panels or slabs end-to-end and side-by-side one another. However, all of the panels must be level and reliably connected one to the next in order to establish a smooth and continuous driving surface. 
     A conventional technique to connect a first concrete panel to an adjacent panel is by means of dowel bar joints. A series of surface grooves are formed along the tops of opposing ends of the first and adjacent panels. The surface grooves between the panels are axially aligned. A corresponding set of dowel bars are simply laid in respective ones of the surface grooves so that each dowel bar extends between the first and adjacent panels. The surface grooves are filled with a bonding material in order to cover and hold the dowel bars in place. The dowel bars are intended to connect the panels together and prevent shifting and a separation of one panel from the other. 
     However, over time, heavy wear, changing weather patterns, and movement of the earth bed upon which the roadway is constructed, mechanical forces are applied to the ends of the panels which may cause the dowel bar joints between adjacent panels to loosen. By way of particular example, the panels may experience thermal expansion or contraction and move relative to one another as a result thereof. In this case, the panels may buckle such that the bars will be dislodged from the grooves in which they are located. Consequently, the top surface-mounted dowel bars may pop out of the roadway to not only create a potentially hazardous driving surface but to also permit gaps to form and widen between adjacent panels. Such gaps can adversely affect the integrity of the entire roadway and require frequent and expensive repairs. 
     Therefore, what is desirable is a more reliable joint by which to overcome the aforementioned problems inherent with the use of the conventional surface-mounted dowel bars and be able to accommodate a movement or shifting of an adjacent pair of concrete panels in order to ensure a stable and long-term end-to-end connection of one panel to the next. 
     Reference may be made to our Patent application Ser. No. 13/795,952 filed Mar. 12, 2013 for an example of a reliable joint for connecting a first precast concrete panel to an adjacent panel during roadway construction or repair. 
     SUMMARY OF THE INVENTION 
     In general terms, disclosed herein are an apparatus and method by which a panel or slab is joined end-to-end (or side-by-side) an adjacent panel. According to a preferred embodiment, the panels to which the apparatus and method relate are pre-cast concrete panels of the kind that are typically laid on a roadbed and used in the construction of a roadway (e.g., freeway) to support vehicular traffic. 
     A first end of a connecting rod is embedded within a first concrete panel so that the opposite end of the connecting rod projects outwardly from the first panel. That is, the first end of the connecting rod is affixed (by means of epoxy or the like) inside a rod retaining channel that is formed in the first panel so as to be separated from and spaced below the top of the first panel. A rod-receiving channel is formed in an opposing end of the adjacent panel so as to be separated from and spaced below the top of the adjacent panel. The diameter of the rod-receiving channel is preferably greater than the diameter of the rod retaining channel. When the first and adjacent panels are lowered onto the road bed, the connecting rod which projects from the rod-receiving channel of the first panel is axially aligned for receipt by the rod-receiving channel of the adjacent panel. 
     More particularly, with the first and adjacent concrete panels laying next to one another on the road bed, the adjacent panel is pushed along the road bed towards the first panel until the panels are aligned end-to-end and the connecting rod from the first panel is received inwardly of the axially-aligned rod-receiving channel of the adjacent panel. An optional resilient bumper is located at the end of the rod-receiving channel to absorb the impact forces and shock that may be created by the connecting rod moving through the mating pocket. The rod-receiving channel is then filled with concrete or grout by way of an injection port through the top of the adjacent panel, whereby to affix the connecting rod in place. The connecting rod is therefore securely held between the first and adjacent concrete panels at a location below the tops thereof to establish a reliable joint for connecting one panel to the other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a first concrete panel laying on a road bed and having a connecting rod projecting outwardly therefrom and an adjacent concrete panel being lowered into place next to the first panel; 
         FIG. 2  shows the adjacent concrete panel laying on the road bed next to the first panel and having a rod-receiving channel that is axially-aligned with the connecting rod of the first panel; 
         FIG. 3  shows the first and adjacent concrete panels positioned end-to-end one another with the connecting rod which projects from the first panel received by the axially-aligned rod-receiving channel of the adjacent panel; and 
         FIG. 4  shows the rod-receiving channel of the adjacent panel after being filled with a bonding material by which to affix the connecting rod therewithin so as to create a reliable joint by which the first and adjacent concrete panels are connected together to create a continuous flat surface such as a roadway, or the like. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings, an apparatus and a method are described for enabling a first (e.g., precast) concrete panel or slab  1  to be reliably joined to an adjacent (e.g., precast) concrete panel or slab  3 . The apparatus and method herein disclosed have particular application for use during roadway (e.g., freeway) construction and/or repair where a large number of heavy pre-cast concrete panels are laid end-to-end and/or side-by-side and connected to one another to create a smooth and continuous driveway over which vehicular traffic will travel. However, it is to be understood that the apparatus and method herein disclosed are applicable to the construction of any continuous surface such as a runway at an airport to be produced by a series of panels, slabs or the like that are manufactured from concrete (whether precast or not) or any other durable and wear-resistant material to be laid over a road bed or a similar support foundation. It is also to be understood that either one of the panels  1  or  3  can be located at the intersection of adjacent panels that are laid end-to-end and side-by-side. 
     Each precast concrete panel  1  and  3  has a respective connecting rod  5  and  7  embedded within and projecting outwardly from one end thereof. The connecting rods  5  and  7  may be solid or hollow, cylindrical or square bars, tubes, pins, or the like. Each panel  1  and  3  also has a respective rod-receiving channel (only one of which  9  being shown) formed in the opposite end. Although each of the panels  1  and  3  is shown having a single connecting rod and a single rod-receiving channel, it is to be understood that the panels may also have a plurality of such rods and channels. As will be explained in greater detail hereinafter, the panels  1  and  3  are positioned end-to-end or side-by-side one another on a road bed. The connecting rod  5  projecting from one end of a first panel (e.g.,  1 ) is axially-aligned with the rod-receiving channel  9  formed in the opposing end of the adjacent panel (e.g.,  3 ). The adjacent panel  3  is moved towards the first panel  1  until the connecting rod  5  which projects from panel  1  is received inwardly of the oppositely-aligned rod-receiving channel  9  of the adjacent panel  3 , whereby the panels  1  and  3  can be joined to one another atop the road bed for building or repairing a roadway, or the like. Although a pair of adjacent panels  1  and  3  are shown in the drawings to be connected end-to-end one another, it is to be understood that any number of panels can be joined together in the manner described above depending upon the size and nature of the roadway. 
     Referring specifically to  FIG. 1 , the first precast concrete panel  1  is shown lying on the road bed.  FIG. 1  also shows the connecting rod  5  having a first end embedded within a first end of the panel  1  so as to lie along the longitudinal axis thereof. The opposite end of the connecting rod  5  projects outwardly from the first end of panel  1 . In this regard, a relatively narrow rod retaining channel  10  is formed in the first end of the first panel  1 . By way of example only, the rod retaining channel  10  is cylindrical with an ideal diameter of about 1 ⅝ inches so as to receive the connecting rod  5  therewithin. The rod retaining channel  10  is filled with an adhesive bonding material (e.g., epoxy)  12  in order to affix the first end of the connecting rod  5  in place inside the channel  10  so that the opposite end of the rod  5  projects outwardly from the first end of the panel  1 . 
     The adjacent precast concrete panel  3  is shown having the rod-receiving channel  9  formed therein so as to lie along the longitudinal axis thereof and be axially aligned with the connecting rod  5  which projects outwardly from the first panel  1 . Each of the rod retaining channel  10  shown in the first concrete panel  1  and the rod-receiving channel  9  shown in the adjacent concrete panel  3  are preferably formed by means of appropriately-sized depression cylinders or molds (not shown) that are removably inserted into the opposite ends of the panels during the panel manufacturing (e.g., casting) process, whereby the rod  5  and channel  9  are separated from and spaced below the tops of the respective panels  1  and  3 . The size of the rod-receiving channel  9  is significantly wider than the size of rod retaining channel  10  for an advantage that will soon be explained. By way of example only, the rod-receiving channel  9  is cylindrical with an ideal diameter of about 3 inches. 
     An injection port  14  (only one of which being shown) is formed in the top of each concrete panel  1  and  3  so as to communicate with the longitudinally-extending rod-receiving channel  9  thereof. The injection port  14  is preferably formed by means of an appropriately-sized tube or cylinder (not shown) that is removably inserted downwardly through the tops of the panels during the manufacturing (e.g., casting) process. An optional bumper or stop  16  is located at the end of the rod-receiving channel  9  of each concrete panel  1  and  3 . The bumper  16  is preferably manufactured from a resilient material to absorb impact forces and reduce shock when the connecting rod  5  moves inwardly through the rod-receiving channel  9  whereby to minimize damage to the adjacent panel  3  after the panels  1  and  3  have been joined together as will now be described. 
       FIG. 1  shows the first concrete panel  1  laying atop the road bed. The adjacent concrete panel  3  is typically lowered into place on the road bed by means of an overhead crane, or the like (not shown).  FIG. 2  shows the adjacent concrete panel  3  laying upon the roadway next to the first panel  1 . It may be appreciated that the adjacent panel  3  is lowered into place next to the first panel  1  such that the connecting rod  5  which projects outwardly from the first end of the first panel is axially aligned for receipt by the rod-receiving channel  9  that is formed in the opposing end of the adjacent panel. 
       FIG. 3  shows the adjacent concrete panel  3  after being moved (e.g., by means of the overhead crane) towards and positioned end-to-end the first concrete panel  1  so that the connecting rod  5  from the first panel  1  is received inwardly of the axially-aligned rod-receiving channel  9  of the adjacent panel  3  so as to move into contact with the resilient bumper  16  at the end of the channel  9 . By virtue of the rod-receiving channel  9  having a relatively wide diameter (compared to the diameter of the rod retaining channel  10 ), an allowance is made for cases where the connecting rod  5  and rod-receiving channel  9  are not perfectly aligned with one another. Inasmuch as the connecting rod  5  and the rod-receiving channel  9  in which the rod is received are spaced below the tops of the respective panels  1  and  3 , the connecting rod  5  is less likely to pop out and separate from the panels as could be the case when conventional surface-mounted dowel bars are used to join the panels together. Once the panels  1  and  3  are joined together, they may be elevated above the road bed and leveled relative to one another. 
     In  FIG. 4 , a bonding material  20  (e.g., concrete or grout) is pumped down the injection port  14  formed through the top of the adjacent panel  3  so as to fill the rod-receiving channel  9  and surround the connecting rod  5  received therein. The same bonding material  20  may also be used to fill any gap  22  between the panels  1  and  3 . Once the bonding material dries and cures, the connecting rod  9  will be affixed in place within the rod-receiving channel  9  to create a reliable joint for connecting the first and adjacent concrete panels end-to-end one another to establish a continuous flat surface thereover such as that used for constructing a roadway. 
     The resilient bumper  16  accommodates an axial displacement of the connecting rod  5  as a result of the panels  1  and  3  expanding or contracting over time or being subjected to mechanical forces. The bumper  16  absorbs the shock and impact forces generated by a movement of the connecting rod  5  thereagainst. In this same regard, an optional bumper (not shown) can also be located at the end of the rod-retaining channel  10  formed in the first concrete panel  1  such that bumpers will lie at opposite ends of the connecting rod  5 .