Abstract:
An apparatus and method to install contraction joints in concrete slabs. The method uses a device, which inserts a strip of plastic or paper tape into freshly laced concrete, as the device is driven across a concrete slab. The tape is folded immediately prior to being inserted into freshly placed concrete, and functions to weaken the slab at the contraction joint location for the purpose of causing a crack to form in the slab. Plastic tape can be used, which functions as a moisture vapor retarder, and thereby, protects floor coverings from moisture damage, such as mold and mildew, at contraction joint locations.

Description:
[0001]    An apparatus and method to install contraction joints in concrete slabs. The method uses a device, which inserts a strip of plastic or paper tape into freshly placed concrete, as the device is driven across a concrete slab. The tape is folded immediately prior to being inserted into freshly placed concrete, and functions to weaken the slab at the contraction joint location for the purpose of causing a crack to form in the slab. Plastic tape can be used, which functions as a moisture vapor retarder, and thereby, protects floor coverings from moisture damage, such as mold and mildew, at contraction joint locations. 
       BACKGROUND OF INVENTION 
       [0002]    The present invention relates to creating discontinuities in the upper portion of concrete slabs, also known as contraction joints. In particular, the present invention provides for inserting a flexible material such as tape into the upper portion of a plastic concrete slab to create a contraction joint. 
         [0003]    Contraction joints serve the purpose of controlling the location of cracks in concrete slabs due to thermal and drying shrinkage behavior of concrete. The joints weaken the slab so cracks occur at the joint locations, and in, this manner, minimize the occurrence of random cracks. Conventional knowledge proposes that the depth of contraction joints should be one-fourth the thickness of the slab, and spacing of the joints to range from 24 to 36 times the thickness of the slab. 
         [0004]    Several methods of installing contraction joints are currently in use by the construction industry. The oldest method uses a grooving tool to create a score line or joint in a slab. Typically grooving tools are employed for small slabs such as sidewalks. Inserting strips of wood, plastic, or metal to function as contraction joints is also standard, but problems occur when the strips are not installed vertically, which happens when aggregate particles obstruct insertion. Also, strips that are not pushed flush or below the surface can interfere with finishing the surface of the concrete. The method of inserting materials for contraction joints is usually limited to medium sized slabs, such as residential house slabs and small warehouses. 
         [0005]    Today, the most common method of installing contraction joints is by saw cutting. The original saw cutting method used water-cooled saw blades, where it was necessary to allow the concrete to develop sufficient strength, prior to saw cutting, in order for aggregate particles to resist raveling along the edges of the saw cut. A time delay was required before saw cutting to allow concrete to develop strength, and in many cases, this delay permitted random cracks to develop before the contraction joints were installed. The newer saw cutting method, called early entry saw cutting (U.S. Pat. No. 5,582,899 “Concrete Surface with Early Cut Grooves” by Chiuminatta, Dec. 10, 1996) uses a machine that allows cutting of the concrete immediately after final finishing operations. Cutting concrete at this early age has successfully minimized random cracks because the joints were installed before thermal contraction or drying shrinkage of concrete occurred. Limitations with the method are the slow process of saw cutting concrete and the high expense of diamond blades. The installed cost of contraction joints made according to the present invention is less than half that of using the method of early entry saw cutting. 
         [0006]    A common problem exists with many of the prior art methods of creating contraction joints. Cracks that occur at contraction joint locations are paths for moisture from below the slab to the surface. If floor covering, such as sheet vinyl, carpet, or wood, are used, then a problem can occur by the presence of moisture under the slab. One common problem in the house building industry is related to vinyl floor coverings bonded to concrete slabs by latex adhesive. At contraction joint locations, where moisture from the sand or soil below the slab can easily rise up through the crack in the slab, an environment is created for mold growth on the underside of the vinyl. The same situation can occur with carpet and wood, but wood is also vulnerable to expansion and warping by absorbing moisture. To prevent moisture from damaging the floor coverings, contraction joints need to be filled, typically with epoxy or polyurethane materials. This operation is time consuming and expensive. The current invention eliminates the expense of filling contraction joints. 
         [0007]    Prior art methods of inserting flexible materials into fresh concrete are reviewed herein. The most relevant patents were by J. N. Heltzel. The first patent was U.S. Pat. No. 1,697,563, “Concrete Surfacing Joint and Means for and Method of Forming the Same”, issued Jan. 1, 1929. The method used a mandrel to push into plastic concrete a flexible material to form a contraction joint. Discrete lengths of strip material are laid out on the surface of the concrete slab and then a mandrel pushes the strip of material into the concrete using vibration or jarring action. This is a step-by-step process of inserting discrete lengths of material into the concrete. The method required “water-proof paper, fabric, rubber, sheet metal, or other easily bendable material,” but all the materials had to be water-proof because the material was laid out on the fresh concrete prior to being pushed into the concrete; and, if non-waterproof paper were used, the paper would absorb water and be too weak to resist the action of insertion. The current invention overcomes these limitations by using a rotating insertion blade to fold the material immediately prior to insertion into the concrete; hence, non-waterproof paper can be used and a continuous operation can occur by using an “endless” strip of material that is supplied by a spool carried on the device. 
         [0008]    The second patent by Heltzel was U.S. Pat. No. 1,740,345, “Traffic Line and Joint Machine and Method of Producing Same”, issued Dec. 17, 1929. This invention describes a large machine that spans highway pavement for inserting long strips of material into the pavement. The machine can install longitudinal and transverse joints. A rotating blade is used to form a slot in the plastic concrete followed by separate operations where a strip of material is laid out over the slot and then a long mandrel blade is used to push the material into the concrete. The flexible material is mounted on a roll. In contrast, the current invention continuously installs a strip of material into concrete. The rotating insertion blade pushes the tape into the concrete in one operation, which eliminates the separate operations, required by Heltzel&#39;s device, of creating a slot in the concrete and then laying out the strip of material, and then inserting the material into the concrete. 
         [0009]    The third patent by Heltzel, U.S. Pat. No. 1,997,216, “Method of and Means for Producing Concrete Surfacing Joints”, issued Apr. 9, 1935, provided for manually cutting a slot in plastic concrete by using a rotating blade. After cutting the slot, in a separate operation material is laid over the slot, and then the rotating blade is used to insert the material into the concrete. Three operations were required. The current invention uses one operation to insert an “endless” strip of material into concrete for the contraction joint. 
         [0010]    Later art by Gunert, U.S. Pat. No. 3,194,130, “Apparatus for Forming a Weakened Zone in Pavements”, issued Jul. 13, 1965, describes a large machine that continuously creates a slot in plastic concrete and inserts material fed off of a roll. The insertion material is stiff in its vertical orientation and flexible in its horizontal orientation. The slot is formed by two blades, which are spaced such that the insertion material is run between these blades in its vertical orientation as it is embedded into the concrete. The material is not folded, as is the case for the current invention. The machine is used only for forming contraction joints in the longitudinal direction of pavements. No method was described to form joints transverse to the longitudinal joints. 
         [0011]    L. A. Shaw and R. D. Shaw received patents that use a folded strip of material for contraction joints, U.S. Pat. Nos. 7,334,962 and 7,381,007, issued Feb. 26, 2008 and Jun. 3, 2008, respectively. Their method installs taut wires in a form over which is hung flexible material. This operation occurs prior to casting concrete. The folded material forms the contraction joint. These patents do not cover the current invention, which inserts material into concrete after placement. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention provides an installer, a connection made with that installer for continuously inserting tape, wound on a roll, below a top surface of a plastic concrete slab. The installer is made up of a base that is formed so as to be able be supported by and to travel over the top surface of the plastic concrete slab, a rotating insertion blade supported by the base, the rotating insertion blade reaching below the base, the rotating insertion blade having an edge, and a fork supported by the base, the fork being located above the rotating insertion blade, the fork having an opening that can receive an axle on which the tape wound on the roll may be received. Preferably, the fork need only be located higher than the axis of the insertion blade to be located above the insertion blade. 
         [0013]    In the preferred embodiment the opening in the fork for supporting the axle is a slot that allows the height of the axle to change depending on the size of the roll of tape. 
         [0014]    In the preferred embodiment, the rotating insertion blade is formed as a disc and the edge of the rotating insertion blade is a continuous, outer circumferential edge. 
         [0015]    The present invention provides a device for installing contraction joints in concrete slabs where a roll of tape, which is the insertion material, preferably sits on top of a rotating insertion blade, and the tape is folded immediately prior to insertion into fresh concrete by the insertion blade. In the preferred embodiment, the tape is wound on a roll and the roll is mounted on an axle with the roll receiving the axle. The axle is received in the slot of the fork such that the tape wound on the roll rests upon the rotating insertion blade. 
         [0016]    In the preferred embodiment, the roll of tape rotates in a direction opposite to the rotation of the insertion blade. In an alternate embodiment, the roll of tape rotates in the same direction as the rotation of the insertion blade. 
         [0017]    In a preferred embodiment, the tape wound on the roll is disposed between first and second side members, which make up a pair of forks, which are attached to the base, and the first and second side members are formed with first and second guide rails that bracket the tape wound on the roll. 
         [0018]    The present invention also provides a device where the machine can be reconfigured to accommodate tapes of various widths. In one preferred form of the invention, the reconfiguration can be performed rapidly by sliding guide rail extenders over guide rails mounted on side members that bracket the roll of tape. 
         [0019]    In an alternate embodiment, the reconfiguration is performed using parts already contained on the device. No parts, other than those on the machine, are required. 
         [0020]    In one preferred embodiment of the present invention, the installer is provided with a parting blade that is attached to the base, and the parting blade reaches below the base and is aligned with the rotating insertion blade. The parting blade is placed in front of the insertion blade with respect to the direction of travel of the installer. The parting blade is preferably made with a pointed tip and the parting blade is preferably made with a sloping lower surface. These features enable the blade to cut through or push down other inserted tapes the installer may encounter. 
         [0021]    In a preferred embodiment, the installer is formed with a narrow slot that can receive and frictionally hold the insertion tape taut while the device is moved above the concrete slab. 
         [0022]    The present invention provides a device or installer that can be manually pushed or pulled across a plastic concrete slab with a pole or some other extending device that is releasably attached to the installer or the device can be propelled across a concrete slab by a propulsion device that is made part of the installer and has its own power source. 
         [0023]    The present invention provides a method, and a connection made by that method, of continuously inserting tape partially wound on a roll below a top surface of a plastic concrete slab. According to the method of the present invention an installer is used that has a base that is formed so as to be supported by and to travel over the top surface of the plastic concrete slab. The installer also has a rotating insertion blade supported by the base, the rotating insertion blade reaching below the base and above the base, the rotating insertion blade having an edge. The installer also has a fork that is supported by the base, the fork being located above the rotating insertion blade, the fork preferably having a slot. According to the method of the present invention, the tape partially wound on the roll is mounted onto the axle with the roll receiving the axle. The tape has a distal end and opposed longitudinal side edges. The axle is placed into the slot of the fork such that the tape wound on the roll rests upon the rotating insertion blade. The distal end of the tape is then pulled over a portion of the edge of the rotating insertion blade, such that a portion of the edge of the rotating insertion blade contacts the tape between the opposed longitudinal side edges. The installer is then placed on the top surface of the plastic concrete slab such that the base of the installer rests on the top surface of the plastic concrete slab, and a portion of the rotating insertion blade is inserted below the top surface of the plastic concrete slab, and also a portion of the tape is inserted below the top surface of the plastic concrete slab. The portion of the tape that is inserted below the top surface of the plastic concrete slab becomes attached to the plastic concrete in the slab with which it is in contact. The installer is then driven over the plastic concrete slab, such that the rotating insertion blade rotates and thereby pulls tape from where the tape is wound on the roll and inserts further portions of the tape below the top surface of the concrete slab. 
         [0024]    The present invention provides a method of installing contraction joints that occurs immediately after screeding of concrete and before bullfloating, floating, or troweling the concrete surface. 
         [0025]    The present invention also provides a method where the tape for insertion into fresh concrete may be folded at most any point across the width of the tape. According to the present invention, the portions of the tape inserted below the top surface of the concrete slab are folded longitudinally such that a longitudinal fold in the tape is placed in the plastic concrete slab and the opposed longitudinal side edges of the tape are disposed above the longitudinal fold. 
         [0026]    The present invention also provides a method of installing tape into a concrete slab where the portions of the tape inserted below the top surface of the concrete slab continuously extend between first and second side edges of the plastic concrete slab. 
         [0027]    The present invention also provides a method where the tape for insertion can be non-waterproof paper, which allows for easy cutting or piercing when joints in the transverse direction are installed. The present invention also provides a method where the one tape that is already installed in the concrete slab can be pushed down deeper into the slab by the parting blade when joints in the transverse direction are installed. The present invention also provides a method where the tape for insertion is moisture vapor retarding material, which will create a contraction joint that retards moisture transmission through the contraction joint. 
         [0028]    In the present invention the edges of the tape can be physically modified by holes, slits, notches, or other discontinuities or extensions or surface treatment so that adhesion to concrete is insured. In the present invention the holes, slits, or notches on each side of the folded tape are staggered along the length of the tape. 
         [0029]    The present invention also provides a method of installing tape in a plastic concrete slab where a first tape, which is already installed in the plastic concrete slab, is pushed down by the device as a second transverse tape is installed. In an alternate embodiment of the invention the first tape that is already installed in the slab is not pushed down during installation of the second tape, but rather the second tape is installed above the first tape. 
         [0030]    In the preferred form of the invention the tape is continuous in length and spans continuously from one edge of the concrete slab to its opposed edge, as discontinuous lengths of tape would not provide a moisture retarding barrier. Also, in the preferred form of the invention, the tape creates a continuous barrier so that water on top of the slab does not transfer through contraction joints to the bottom of the slab, which could wet the subsoil. 
         [0031]    It is an object of the present invention to provide contraction joints in a concrete slab, the contraction joints being formed with a vapor retarding barrier such that cracks occurring at the contraction joints will have a vapor retarding barrier present that should prevent the transmission of moisture through the crack from above or below the slab. 
         [0032]    It is an object of the present invention to provide a portable device for installing flexible tape as a contraction joint. 
         [0033]    It is an object of the present invention to use only a single blade to install a flexible tape as a contraction joint in a plastic concrete slab. 
         [0034]    In the preferred embodiment, the fork and the insertion blade are pivotly connected to the base, the edge of the insertion blade is formed with teeth and keels are provided on the base. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]      FIG. 1  is a perspective view of the installer of the present invention being pushed over the top surface of a plastic concrete slab. 
           [0036]      FIG. 2  is a side view of the installer of the present invention with portions of the rotating insertion blade and the roll of tape shown in dotted lines for clarity. The guide rails are also shown in dotted lines. 
           [0037]      FIG. 3  is a rear view of the installer of the present invention with a roll of tape mounted on the installer. 
           [0038]      FIG. 4  is a side view of the installer of the present invention being pushed over the top surface of a plastic concrete slab by a pole. The plastic concrete slab is shown in a side sectional view so that the tape and the portions of the installer inserted into the plastic concrete slab can be seen. 
           [0039]      FIG. 5  is a perspective view of the base of the installer. 
           [0040]      FIG. 6  is a detail sectional view of a side plate of the installer showing a cross section of a guide rail on the inside surface of the side plate. 
           [0041]      FIG. 7  is a schematic front view of the rotating insertion blade and its axis inserting a portion of folded tape into a plastic concrete slab 
           [0042]      FIG. 8  is front sectional view of a hardened concrete slab with a portion of tape inserted according to the present invention with a crack formed in the concrete that runs from the bottom of the slab to the top of the slab with the tape serving as a barrier between the top and bottom portions of the crack due to the adhesion of the tape to the concrete on both sides of the crack. 
           [0043]      FIG. 9   a  is perspective view of a portion of tape with large holes disposed near the longitudinal side edges of the tape. 
           [0044]      FIG. 9   b  is perspective view of a portion of tape with small holes disposed near the longitudinal side edges of the tape. 
           [0045]      FIG. 9   c  is perspective view of a portion of tape with slits disposed near the longitudinal side edges of the tape. 
           [0046]      FIG. 9   d  is perspective view of a portion of tape with notches disposed in the longitudinal side edges of the tape. 
           [0047]      FIG. 10  is a perspective view of a portion of a concrete slab with portions of tape inserted into the slab according to the present invention with one tape having been inserted over the first tape inserted into the slab and the installer of the present invention having pushed the first tape so installed below the second tape so installed. 
           [0048]      FIG. 11  is a perspective, inside view of an alternate side plate of the present invention with an alternate fork and guide members for the roll of tape. 
           [0049]      FIG. 12  is a perspective, outside view of an alternate side plate of the present invention with an alternate fork and guide members for the roll of tape. 
           [0050]      FIG. 13  is a top view of a form of the invention with alternate side plates forks and guide members holding the roll of tape. 
           [0051]      FIG. 14  is a top view of a form of the invention with alternate side plates forks and guide members holding the roll of tape. 
           [0052]      FIG. 15  is a side view of an alternate preferred embodiment of the installer. 
           [0053]      FIG. 16  is rear view of the installer shown in  FIG. 15  without the pole. 
           [0054]      FIG. 17  is a side sectional view of the alternate preferred embodiment shown in  FIG. 15 , where the tape roll is shown riding on the side of the insertion blade. Also, the arrangement of the springs are shown. 
           [0055]      FIG. 18  is a top view of the T-headed pin. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0056]      FIG. 1  shows the installer  10  for continuously inserting tape  11  wound on a roll  34  below a top surface  27  of a plastic concrete slab  13 . The installer  10  has a base  12  that is formed so as to be able be supported by and to travel over the top surface  27  of the plastic concrete slab  13 . The installer  10  also has a rotating insertion blade  14  supported by the base  12 . In the preferred embodiment, there is only a single rotating insertion blade  14 . The rotating insertion blade  14  reaches below the base  12 . The rotating insertion blade  14  has an edge  29 . The installer  10  also has a fork supported  31  by the base  12 . The fork  31  is located above the rotating insertion blade  14 . The fork  31  has a slot  26  that can receive an axle  28  on which the tape  11  wound on the roll  34  may be received. 
         [0057]    Preferably, the rotating insertion blade  14  is formed as a disc and the edge  29  of the rotating insertion blade  14  is a continuous, outer circumferential edge  29 . Also preferably, as shown in  FIG. 4 , the tape  11  wound on a roll  34  is mounted on an axle  28  with the roll  34  receiving the axle  28  and the axle  28  is received in the slot  26  of the fork  31  such that the tape  11  wound on the roll  34  rests upon the rotating insertion blade  14 . 
         [0058]    In the preferred embodiment, as shown in  FIG. 1 , the tape  11  wound on the roll  34  is disposed between first and second side members  18 , which are preferably side plates. As shown in  FIGS. 2 and 3 , in one preferred embodiment of the invention, the first and second side members  18  are formed with first and second guide rails  32  that bracket the tape  11  wound on the roll  34 . As shown in  FIG. 6 , the first and second guide rails  32  can receive guide rail extensions  33  that fit over and partially encompass shoulders  35  on the first and second guide rails  32 . 
         [0059]    As shown in  FIG. 2 , in one preferred embodiment, a parting blade  60  is attached to the base  12 , and the parting blade  60  reaches below the base  12  and is aligned with the rotating insertion blade  14 . The parting blade  60  is preferably made with a pointed tip  62  projecting in the direction of travel of the installer  10 , and the parting blade  60  is made with a sloping lower surface  63 , the use of which is described later herein. 
         [0060]    As shown in  FIG. 3 , the installer  10  is preferably formed with a narrow slot  68  that can receive and grasp the tape  11 . 
         [0061]    As is shown in  FIG. 4 , in one preferred embodiment of the invention, a pole  50  or other type of propulsion device can be releasably attached to the base  12  for driving the installer across the top surface  27  of the plastic concrete slab  13 . 
         [0062]      FIG. 4  also shows the connection made according to the present invention, wherein a tape  11  that is partially wound on a roll  34  has a distal end  45  and a leading portion  48  that are inserted below a top surface  27  of a plastic concrete slab  13 . The tape  11  has opposed longitudinal side edges  46 , and a portion of the tape is disposed along a portion of the edge of the rotating insertion blade  14  with the portion of the edge  29  of the rotating insertion blade  14  being disposed between the opposed longitudinal side edges  46  of the tape  11 , resulting in a fold  47  being formed in the portion of the tape  11  that is disposed below the top surface  27  of the plastic concrete slab  13 , as shown in  FIG. 7 . 
         [0063]      FIG. 1  shows the invention in operation on a concrete slab. The installer  10  contains a base plate  12 , which rides on the surface  27  of a newly placed concrete slab  13 . A long-handled pole  50  is used to push the installer  10  across the slab. 
         [0064]      FIG. 2  is a side view of the installer  10  and  FIG. 3  is a rear view of the device. The basic components of the invention are a rotating insertion blade  14  and a roll of tape  16  mounted above, and riding on, the insertion blade  14 . Side plates  18  serve two functions: to support the axis  20  of the insertion blade  14  and provide guide slots  26  for the axle or axis  28  of the roll of tape  16 . The side plates  18  are attached to the base plate  12  by means of angles attached to the base plate. Because of the slots  26 , the roll of tape  16  rides on the insertion blade  14  with gravity as the force for contact. The handles  30  are not only for lifting the device, but also function to maintain the proper spacing between sidewalls  18 . Guide rails  32  are used to align or center the tape roll  16  over the insertion blade  14 , and to assist the tape roll  16  in freely sliding downward as tape is consumed. In this manner, gravity maintains contact between the tape roll  16  and insertion blade  14 . 
         [0065]      FIG. 4  shows that the insertion blade  14  folds a single strip of tape  17 , which feeds off of tape roll  16 , just prior to inserting the tape into the fresh concrete  13 . As shown in  FIG. 4 , for forward travel of the installer  10 , the insertion blade  14  will rotate counterclockwise due to friction between the insertion blade and concrete. Proper mounting of the tape is such that the tape roll  16  rotates clockwise. 
         [0066]      FIG. 5  shows that the base plate  12  to the device is preferably rectangular, and contains an open central area  36  where the insertion blade  14  extends into the concrete. The upturned edge  38  at the front of the device helps the base plate  12  to ride over rough surfaces of fresh concrete, and the upturned edge  40  at the rear of the open area  36  helps to push down concrete that is lifted by the rotating insertion blade  14 . The notched area  42  at the rear of the base plate  12  assists in properly positioning the tape strip  17  when the installer  10  is placed on fresh concrete  13 . The slot  44  at the front of the open area  36  is for the parting blade  60 , shown in  FIG. 4 . 
         [0067]    In  FIG. 3 , a push rail  64  is shown at the rear of the installer  10 , which contains a wide slot  66  and narrow slot  68 . The wide slot  66  is used to attach the long push pole  50 . The connection between push pole  50  and the apparatus is a headed pin  52  at the end of pole  50  that slips into the wide slot  66 , as shown in  FIG. 4 . Narrow slot  68  is used to temporarily hold the tape strip  17  as the device is manually moved above the surface of the plastic concrete slab  13  from one location to another. 
         [0068]    The preferred embodiment of the device as described herein envisioned for application on slabs whose thickness ranges from 4 to 6 in., but of course its application is not limited to slabs with those thicknesses. In the preferred embodiment, the device base plate  12  is 12 in. wide by 20 in. long, and the sidewall  18  is 12 in. high. The insertion blade  14  is 7 in. diameter and has a thickness of about 1/16 in. The tape roll  16  is about 8 in. diameter. The tape itself would range from 2 to 3 in. wide. Typically, a slab of 4-in. thickness would use 2-in. wide tape, and a 6-in. thick slab would use 3-in. wide tape. The tape would be folded in half by the insertion blade  14 , so the contraction joint depth would be 1 in. for the 4-in. slab and 1.5-in. for the 6-in. slab. If the tape itself had a thickness of 6 mils, approximately 500 linear feet of tape would be available on roll  16 . Preferred materials for the construction of the device are aluminum or magnesium for the base plate  12 , and aluminum for other elements above the base plate, except for the insertion blade, which is steel. 
         [0069]    In one preferred embodiment, the distance separating the sidewalls  18  is 3.5 in. The guide rails  32  are each slightly less than ¼ in. thick; hence, a tape roll  16  of 3 in. width freely slides between the guide rails  32 . For tape rolls  16  narrower than 3-in., the guide rails are made wider by sliding guide rail extenders  33  over the guide rails. This is shown in  FIG. 6 . In this embodiment of the guide rails  32  and the extenders  33 , the guide rails are formed as elongated members with a distal surface disposed away from the side walls  18  that is wider than the surface of the guide rail that is proximal the side walls  18 . This creates shoulders which can be grasped by elongated tabs of the extenders  33 . 
         [0070]      FIG. 2  shows multiple holes  21  located in the sidewalls  18  at different heights to allow the insertion blade  14  to be embedded at different depths into the fresh concrete. Knobs  23  containing a short length of threaded rod, attach the axis  20  to the side plates  18 . If the slab were 4 in. thick, the depth of the insertion blade is preferably set at 1.5 in. to accommodate the width of the folded tape  17  at 1 in. and placement of the tape below the surface of the concrete by 0.5 in. If the slab were 6 in. thick, the depth of the insertion blade would be 2.0 in. to accommodate the width of the folded tape at 1.5 in. and placement below the surface of 0.5 in. Inserting the tape below the surface of the concrete by 0.5 in. provides assurance that during finishing operations of bullfloating, floating, and troweling the surface of concrete, the tape will not be contacted. 
         [0071]    The parting blade  60  serves several functions. First, it functions as a keel in assisting the installer  10  to track a straight line as the device is pushed across the slab. Second, the point  62  on the parting blade  60  can pierce existing tape  17  in a slab as new tape is placed perpendicular to the existing tape. Third, the blade  60  can push down existing tape in a slab as new tape is installed perpendicular to the existing tape, which operation will be discussed later. The depth of the parting blade  60  can be adjusted to accommodate different situations as needed. 
         [0072]    A variation in the device is to have the tape folded off-center. In this way a 2-in. wide tape could be used in a 6-in. slab. The tape  17  would be folded off center, as shown in  FIG. 7 , such that one side is 1.5 in. wide and the other side is 0.5 in. wide. The guide rails  32  would be properly sized and installed to place the tape roll  16  off-center on the insertion blade  14 . 
         [0073]    In an alternate embodiment of the device, the side plates  18  are designed differently.  FIGS. 11 and 12  show the alternate design for the side plate  18 , shown here as an alternate side plate  90 .  FIG. 11  is the inside view of the alternate side plate  90 , where tape roll  16  is located; and,  FIG. 12  is the outside view. The original guide rail  32  in  FIG. 2  is now shown as the alternate guide rail  92 , which is attached to the alternate side plate  90  by machine screws  98 . The attachment is by threaded holes  93  in the alternate guide rail  92 . A view port  96  in the side of the alternate side plate  90  is provided to observe tape roll  16  as it nears being used up. Items of the same design as in  FIG. 2  are the handle holes  94  for handles  30 , and multiple holes  21  for attaching the insertion blade  14 . 
         [0074]      FIG. 12  also shows slotted spacers  102  at each machine screw  98  location. The slotted spacers  102  are used to change the location of the alternate guide rail  92  when the roll of tape  16  is to be changed to a different width.  FIG. 13  shows roll of tape  16  mounted between alternate guide rails  92  and alternate side plates  90 . Axis  28  of tape roll  16  is located in guide slot  100 .  FIG. 14  is a similar view to that of  FIG. 13  except the tape is narrower in  FIG. 14 , and the spacer  102  has been arranged accordingly. 
         [0075]    Using specific dimensions, given earlier, for an installer device  10  intended for slabs of thickness 4 to 6 in.,  FIG. 13  shows tape  16  having a 3-in. width (which would be used in a slab of 6-in. thickness).  FIG. 14  shows tape  16  having a 2.5-in. width (for a slab of 5-in. thickness). The change in tape width was a 0.5 in. decrease. The next reduction in tape width would be to 2-in. (for a slab of 4-in. thickness), or another 0.5 in. decrease. The alternate guide rails  92  need to be located closer together by these 0.5 in. increments. For this example, each slotted spacer  102  would be ¼ in. thick. At each machine screw attachment point, one slotted spacer  102  from outside the alternate side plate  90  would be moved between the alternate side plate  90  and alternate guide rail  92 . This maneuver would shift the alternate guide rails  92  closer together by 0.5 in., or to a spacing of 2.5 in. Although not shown, the remaining slotted spacer  102  on the outside of alternate side plate  90  can be moved to the inside so the spacing between guide rails becomes 2.0 in. The advantage of this design is that all the pieces to reconfigure the installer  10  for different width tapes are present on the device. Separate pieces, which can get misplaced or lost, are eliminated. Also, the reconfiguration is done rapidly. The machine screws  98  are loosened, and then the slotted spacers  102  are slipped off machine screw posts, relocated, and slipped back over the machine screw posts, and then the machine screws are retightened. 
         [0076]    An alternate preferred embodiment is shown in  FIG. 15 through 17 . The base plate  12  is configured similarly to that shown in  FIG. 5 . Mounted on the base plate  12  is box  110 , which is comprised of two side plates  18 , front end plate  112 , rear end plate  114 , and two handles  30 . The box  110  is attached to the base plate by the pivot connection  116  at the front portion of the installer  10 . Tape slot  118  is located in the front half of the installer  10  and permits the tape roll axis  28 , which contains tape roll  16 , to move by the force of gravity such that the tape roll  16  contacts and rides on the insertion blade  14 . The elevation of tape axis  28  is always higher in than that of the insertion blade axis  20 . The advantage of mounting the tape roll  16  such that the contact point is on the side of the insertion blade, as opposed to the top of the insertion blade  14 , as shown in  FIG. 2 , is that tape  11  travels a shorter distance on the insertion blade before being inserted into the plastic concrete  13 . Therefore, tape  11  is more stable in remaining centered on the insertion blade  14 . The insertion blade  14  has sharp edges  29  or teeth  140  to assist in preventing sideways slippage of tape  11  off the center position on the insertion blade  14 . In  FIGS. 15 ,  16  and  17 , the teeth  140  are shown as only disposed on a portion of the insertion blade  14 , but ideally the teeth  140  would be disposed around the entire circumference of the insertion blade  14 . 
         [0077]    An insertion blade slot  120  is located in the rear half of box  110 , which permits the insertion blade  14  to be inserted into plastic concrete  13  by various depths. The depths can be conveniently controlled by indents  122 . The maximum height of slot  120  permits the insertion blade  14  to be raised above the base plate  12 . 
         [0078]    Attached to base plate  12  at the rear portion of installer  10  are guide plates  124 , which horizontally confine the box  110 , but vertically allow movement of the box  110 . The height of vertical movement is limited to about 1.5 in. by the top stop  126 , which is part of the guide plate  124 . The bottom stop  128  is part of the rear end plate  114 . Vertical movement of the box  110  permits the insertion blade  14  to ride over reinforcing bars embedded in plastic concrete, which are located higher in the slab than designated by design. When the box  110  rides over a reinforcing bar, the base plate  12  remains in contact with the plastic concrete  13 . 
         [0079]    Springs  130  are attached to the box  110  at the handle  30  and the up-turned edge  40  on the base plate  12 . The springs  130  provide an extra force, which increases the effective weight of the box  110  such that a force almost equal to the total weight of the device is enrolled to push the insertion blade  14  into the plastic concrete  13 . The extra force provided the springs  130  should not exceed the weight of the base plate  120  so as not to lift the base plate from the surface of the concrete when the box  110  is lifted up by the insertion blade  14  riding over a high piece of reinforcing bar in the concrete  13 . 
         [0080]    The rear end plate  114  contains a push bracket  132 , which contains a wide slot  66  to receive a headed pin  136  at the end of pole  50 . The headed pin  136  is T shaped, such that confinement of the T portion by the push bracket  132 , permits better steering of the installer  10  by horizontal movement of pole  50 . The T shaped pin  136  permits free vertical movement of pole  50 .  FIG. 18  shows a configuration of the T shaped headed pin  136 . At the front end of the installer  10  is a pull bracket  134  of similar configuration to that of the push bracket  132 . 
         [0081]    The keels  138  are provided, one along each side of the base plate  12 , to assist the device moving along a straight path as pole  50  pushes or pulls. 
       Operation of Invention 
       [0082]    The installer  10  is used in the following manner. Initially, a roll of tape  16  is placed on top of the insertion blade  14  in the fork  31  and then the distal end  45  of a single strip of tape  17  is run over the insertion blade  14  and then along the bottom of the device. The tape  11  has a distal end  45  and longitudinal side edges  46  and where the tape  11  is in contact with the edge  29  of the blade  14 , it is disposed between the longitudinal side edges  46  of the tape  11 . The edge  29  of the rotating insertion blade  14  is narrower than the tape  11 , and as the blade  14  drives into the concrete the tape  11  folds around the edge  29  such that the portions of the tape  11  inserted below the top surface  29  of the concrete slab  13  are folded longitudinally such that a longitudinal fold  47  in the tape  11  is placed in the plastic concrete slab  13  and the opposed longitudinal side edges  46  of the tape  11  are disposed above the longitudinal fold  47 . 
         [0083]    Prior to placing the installer  10  on the top surface  27  of the concrete slab  13  and the initial insertion of the tape  11  into the concrete slab  13 , if needed the tape can be inserted into slot  68  to hold it in place while the installer  10  is initially set in the plastic concrete slab  38 , and once the device  10  is set, the tape is released from slot  68  and the distal end  45  of the tape is pushed into the plastic concrete slab by hand to the edge of the slab. After the device is placed on the surface of fresh concrete  13 , typically a long-handled pole  50  is used to push the device forward, as shown in  FIG. 1 . Friction between the insertion blade and fresh concrete causes the insertion blade to rotate and the tape  11  adheres to the concrete in the slab  13 . The insertion blade installs the folded tape into the concrete. The long-handled pole is attached to the device in such a manner that back and forth motion can be imparted to the device, which can facilitate the parting blade  60  and insertion blade  14  penetrating stiff concrete by displacing coarse aggregate particles. Under normal concreting conditions, the parting blade  60  and insertion blade  14  easily displace aggregate particles because the concrete will be highly workable at the time of installing the contraction joint. 
         [0084]    Timing for insertion of the tape is immediately after screeding, or leveling-off the concrete surface. Screeding is conducted shortly after concrete is placed in the forms and while the concrete is still highly workable. This operation of installing contraction joints immediately after screeding, and before bullfloating the surface, is not performed by any other contraction joint method. Other methods install joints after bullfloating operations, or after final finishing operations. (Methods exist for placing contraction joints in formwork prior to placing concrete but these methods are not used in the field due to impracticality.) This early installation feature of the invention is highly advantageous, as the early installation of contraction joints provides the best protection against formation of random cracks. The joint is installed prior to bulk volume decreases of the plastic concrete slab. Bulk volume decreases are due to a several factors. There is initial chemical shrinkage, which occurs as fresh concrete stiffens and gains strength during the initial hours after water is introduced to portland cement. Later thermal contraction and autogenous shrinkage occur, and later still drying shrinkage takes place. 
         [0085]    A novel feature of the device is that backward motion of the device is acceptable because the roll of tape  16  rides on the insertion blade  14 . When backward motion occurs the single strip of tape  17  is rewound onto the roll  16 . This action occurs only because the tape is mounted in such a manner that counter-clockwise rotation of the insertion blade  14  causes clockwise-rotation of the tape roll  16 .  FIG. 4  shows the proper method to mount the tape roll  16  over the insertion blade  14 . Rewinding of tape onto the spool with backwards movement of the device is important because the tape strip  17  stays in full contact with the blade and remains centered or aligned on the blade. If the tape strip  17  were to become “loose”, or separated from the insertion blade  14 , then wind could catch the loose tape strip  17  and move it horizontally such that the blade is no longer located at the proper location on the tape. 
         [0086]    Although the above description is the preferred embodiment, the invention can be built having the tape roll  16  and insertion blade  14  not touching, and where the tape strip  17  feeds off of the tape roll  16  such that the rotation of the tape roll  16  and insertion blade  14  are both counter-clockwise, or clockwise. For this alternative embodiment, however, the tape strip  17  will not rewind onto the tape roll  16  during backward movement of the device. 
         [0087]    When the device arrives at the other side edge  55  of the slab, say 10 to 20 ft. away, preferably a second laborer picks up the device, cuts the tape strip  17 , inserts the end of the tape  17 , which is connected to the roll  16 , into narrow slot  68 , picks up and moves the device to the next joint location, places the device onto the concrete surface, disconnects the end of the tape  17  from the narrow slot  68 , and pushes the device to the other side of the slab. The laborer can return to the first strip of tape  11  and push the partially embedded strip of tape  11  into the slab  13  to complete the contraction joint to the edge  55  of the slab  13 . Thus, the portions of the tape  11  inserted below the top surface  27  of the concrete slab  13  continuously extend between first and second side edges  55  of the plastic concrete slab  13 . This process of moving the device across the slab creates contraction joints in one direction, say the east-west direction. Contraction joints are also required in north-south direction. This invention discloses methods to install joint material perpendicular to already installed material, and these methods will be described shortly. 
         [0088]    Slabs having widths of 30 to 40 ft. can have joints installed by the following procedure. Both laborers have long-handled poles  50 . When the device is about 20 ft. away from the first laborer, who pushed the device, the second laborer attaches his pole  50  to the pull plate  70  at the front of the device and pulls the device. A wide slot  66  is located in the pull plate  70 , similar to that of wide slot  66  in the push plate  64 . 
         [0089]    Remote propulsion of the device to traverse wide slabs is an alternative method of getting the device from one side of the formwork to the other side. A method like vibratory locomotion, as disclosed in U.S. Pat. No. 3,916,704, which is herein incorporated by reference, would provide propulsion device mounted on the device to provide the propulsion. This method uses a reciprocating weight, which would be mounted on a larger base plate  12  than proposed earlier, to cause the device to incrementally slide over the surface of fresh concrete. The reciprocation weight moves back and forth in a straight line that is inclined horizontally. As the weight reaches the top of its stroke, the effective weight of the device is reduced and the device slides forward; at the bottom of the stroke, the effective weight of the device is increased, which increases friction, and no back sliding occurs. In this manner, the installer incrementally moves across fresh concrete surfaces by remote control of a power source and the angle of inclination of the reciprocating weight. A use for remote propulsion of the contraction joint installer is for slabs constructed by the laser screed method, where slabs as large as 200×200 ft. can be placed in one day. Hence, the installer needs to traverse distances of 200 ft. in each direction. 
         [0090]    For applications where the contraction joints do not require moisture-retarding characteristics, thin plastic or paper typically 1 to 6 mils (0.001 to 0.006 in.) thick can be used as the insertion material. These tapes typically do not function as moisture retarding materials. Thin plastic or paper tapes are inexpensive insertion materials. Non-waterproof paper can be used as an insertion material because the tape is inserted quickly, while the paper is still dry. 
         [0091]    For applications where contraction joints require moisture-retarder characteristics, plastic sheeting of 6-mil and greater thickness is available commercially with moisture transmission values of less than 0.1 permeance (perm.) Among other companies, Fortifiber Building Systems Group manufactures Moistop Ultra 6 and Ravens Engineered Films manufactures VaporBlock 6, where both products meet the 0.1 perm rating with plastic sheeting of 6-mil thickness.  FIG. 8  shows that each side of the folded tape  17  needs to adhere to hardened concrete  15  after a crack  76  develops, so moisture vapor is blocked.  FIG. 9  shows several methods to enhance and insure adhesion of tape  17  to concrete by providing discontinuities in and extensions from the tape  11 .  FIG. 9   a  shows large holes  80  (¼-inch diameter), while  FIG. 9   b  shows numerous small holes  82  (like pin picks), located along the top edges of the folded tape  17 .  FIG. 9   c  shows slits  84  cut in the tape horizontally, vertically, and diagonally.  FIG. 9   d  shows the top edges with notches  86  cut-out, where the notches are staggered. These methods permit fresh cement paste to run into holes, slits, or overlap the edge of the plastic tape and “grab” the top edge. Also, the surface of the tape  11  that is in contact with the concrete can be roughened to increase adhesion. Thus, a positive mechanism is provided to adhere each side of the tape to the concrete. 
         [0092]    A unique application for plastic tape  17 , which is adhered securely to concrete on each side of the tape, is for contraction joints in pavement. Conventional sawcut contraction joints in pavement allow rainwater to enter the joint, which results in a problem called “pumping”. At the bottom of the crack at a contraction joint, water gets under the edges of pavement because curling of the pavement, due to drying shrinkage, has lifted the edges slightly. Whenever, a car or truck rolls over the contraction joint, the edge of the pavement is pushed down and water is pumped up and out of the joint. The water, which is pumped out, carries along fine soil particles from under the pavement, and eventually with sufficient cycles of pumping the edges are undermined. The pavement is now weak along the edges and cracking can occur due to traffic loads. This invention creates a barrier to rainwater reaching the bottom of the pavement, and thereby, the problem of pumping is mitigated. 
         [0093]    During construction of buildings, slabs-on-ground may be built prior to constructing the superstructure. These slabs are exposed to rainwater before the superstructure is built. Should rainwater get under the slab by entering the contraction joints, the sand or soil under the slab will become wet and may present a moisture vapor emission problem after the superstructure is built and floor coverings are installed. This invention prevents the water placed on top of the slab from running into contraction joints and wetting the sand or soil beneath the slab. 
         [0094]    For most concrete slabs, contraction joints are installed in both directions (north-south and east-west). Prior art by Lusk, U.S. Pat. No. 3,413,901 “Apparatus and Method for Inserting a Continuous and Solid Joint Strip into Plastic Concrete”, Dec. 3, 1968, describes a method to accomplish this task. After the first joint material is installed, the second joint material, which is transverse to the first joint, is installed by using an attachment tool that pierces and cuts the first tape in order to make a path for the second tape. This approach can be used by the current invention when paper tape is used. An advantage of paper tape is that the first tape installed is exposed to a wet environment, that of the fresh concrete, and the paper tape will weaken as it absorbs water. The parting blade  60  with a point will easily cut the tape  17 . This is not the situation if plastic tape were used, as puncturing and cutting plastic tape can be difficult. 
         [0095]    This invention uses a novel method to install the second tape transversely to the first tape. The method does not cut any tape, which is important for tapes used as moisture vapor retarders at contraction joints. The method is described as follows, and shown in  FIG. 10 . The first tape  17  is installed in the slab at a greater depth in the slab than typical, but above the reinforcing bars. For example for a 6-in. slab, the 1.5-in. folded tape  17  is inserted at a depth of 1.0 in. below the surface of the slab in the east-west direction. The second tape  19 , in the north-south direction, gets inserted at a depth of 0.5 in. below the surface of the slab. As the second tape  19  is installed, the parting blade  60  pushed down the first tape  17 . The parting blade is designed with a sloping surface of 30°, more or less, for the purpose of pushing down the first tape. If voids are created in the fresh concrete  13  by pushing down the first tape  17 , the voids will be closed during the finishing operation of bullfloating, which immediately follows joint installation. 
         [0096]    This method of installing joints in two directions can be performed where the first tape does not need to be pushed down by the second tape. Either the first tape is installed deeper in the slab, which can occur if the slab is unreinforced, or the tapes are narrower than the conventional ¼ th  the thickness of the slab, which is technically acceptable because the joints are installed at an early age.