Abstract:
A concrete crack control joint insertion tool to insert joint forming materials into a concrete mixture or alternatively providing means to create a crack control joint without the use of ancillary material. 
     Crack control joint in fresh concrete is formed beneath a rectangular structure supporting linear actuators that drive a blade alone or carrying joint forming materials into a precise location and depth. Crack control joint formation is repeatable completed in a single motion and with continued precise accuracy of placement.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of PPA Ser. No. 60/866,034 filed Nov. 15, 2006 by the present inventors, which is incorporated by reference 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
       [0002]    Not applicable 
       BACKGROUND OF THE INVENTION 
     Field of the Invention (Technical Field) 
       [0003]    The present invention relates to an apparatus and method of creating crack control joints in concrete. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    Objects, advantages and novel features and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
       BRIEF DESCRIPTION OF THE DRAWINGS 
       [0005]    The accompanying drawings which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more of the preferred embodiments of the invention and are not to be construed as limiting the invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0006]    Various non-limiting embodiments of the present invention are described in the document attached hereto. As used herein, the terms “a” or “the” and “an” means one or more. The various figures are illustrative of the various embodiments and are not limiting of the scope of the invention 
         [0007]    Although the invention has been described in detail with particular reference to the preferred embodiments in the attachments, other embodiments can achieve the same results. Various and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover all such modifications and equivalents. The entire disclosures of all references, applications, patents and publications cited above and/or in the attachment, and of the corresponding application(s) are hereby incorporated by reference 
       BACKGROUND OF THE INVENTION 
       [0008]    This invention relates to a machine used to control the location of cracks in hardened concrete by creating a weakened plane in the concrete section by either creating a zone of segregated low-strength paste in a portion of the concrete cross section or by inserting joint forming material into the fresh concrete. When internal stresses build up to a level that requires relief, a crack will form at the weakened plane instead of randomly in the overall concrete structure. This failure is the joint which is conventionally used to control the location of cracking of the cured concrete. 
         [0009]    It is generally accepted that as concrete cures, cracks are randomly generated depending upon the environmental and physical conditions in existence at the time. Control of the location of cracks is extremely important to control the size and spacing of resulting cracks, in order to minimize the access of water through the concrete and to minimize other shrinkage related problems that can cause extreme damage to the structure being built. 
         [0010]    The structural integrity of concrete is created by building the strongest aggregate structure possible with the available aggregates, and gluing them together with the cementitious paste portion of a concrete mixture. The aggregate consists of uniformly graded particles of decreasing size that are designed to create the densest possible void structure within a given unit volume. Cementitious material is used to bond the aggregate particles together. When the cementitious material hardens it binds the individual aggregate particles together, forming a single discreet rigid structural member. The strength of the resulting member is a direct result of the ratio of water to the cementitious particles in the mixture and to efficiency of the adhesion of the aggregate particles. As the cementitious material cures (or hydrates), it shrinks setting up internal tensile stresses in the hardening material. As the stresses increase, they reach a magnitude that exceeds the existing bond strength between the aggregate particles, and a crack is formed, thereby relieving the stresses. Recognizing that cracking is inevitable it is desirable to cause the crack to form in a predetermined location that can be properly mitigated rather than in an unpredictable random pattern that is virtually impossible to mitigate. 
         [0011]    The conventional method of forcing the location of a shrinkage crack is to perform an action that will cause the crack to form in the desired location. This method consists of saw-cutting a groove into “fresh” concrete that is just hard enough to allow saw blades to cut through the concrete without leaving other pressure related defects in the still-hardening concrete. These grooves must be deep enough to ensure that the remaining un-cut portion of the concrete is much weaker than the adjacent sections of the concrete, thereby ensuring that the crack forms at the weakest location within the still-hardening concrete. This operation is difficult to judge, costly to perform and inefficient. An operator can not get onto the concrete to cut the grooves until it has set up sufficiently to bear the weight of the operator and the equipment. Stresses are continuously developing as the concrete hydrates sufficiently to allow the operator and equipment onto the surface of the concrete. However, if the grooves are not cut before the stresses develop, the cracks will have already formed, and the entire attempt to control the cracking will have failed, and the resulting mitigation efforts are much more difficult and costly. 
         [0012]    Another means of generating the weakened plane is to insert a foreign material into the concrete while the paste is still fresh thus ensuring that the weakened plane is installed before any tensile stresses have developed. Commercially available material in the form of a plastic strip to provide the isolation of the aggregate pieces is available and is marketed as Zip Strip or EZ Joint. While these plastic strips have been used successfully, they are extremely difficult to install by hand and when installed are subject to improper installation. A control joint can be quickly and successfully installed by creating a zone of segregated low-strength paste or by inserting a plastic strip by use of the present invention. The present invention ensures the creation of a clean uniform zone of segregated paste as well as the proper installation and alignment of a plastic strip with little cost or effort. 
       SUMMARY OF THE INVENTION 
       [0013]    Therefore a primary object of the present invention is to provide a means to mechanically develop a control joint by generating a weakened plane into the fresh concrete. Another object of the invention is to provide means to ensure that each and every joint is installed in accordance with the required specifications for concrete joint control. 
         [0014]    Another object of the invention is to minimize the labor, time and associated cost to install the joint. 
         [0015]    Still a further object of the invention is to provide means to install the required joint at an opportune time to ensure the efficiency of the crack control operations. 
         [0016]    In order to attain the above-mentioned objects, the present invention is a machine configured to be either portable and manipulated by workers, or attached and operated by concrete placement machinery and in which with one action generates the desired control joint in concrete. 
         [0017]    The machine is placed at the required joint location either by attaching handles to the machine providing the opportunity for the workers to operate the machine or by physical interface to a concrete placement machine. A knife-like blade performs the function of forming the control joint groove by means of its momentary vibratory insertion into the concrete medium or carrying into the concrete medium an attached joint forming material. 
         [0018]    When the machine has been placed in location to generate a control joint, the operator energizes the system causing the knife-like blade to descend into the concrete medium and creating a weakened plane in the matrix, or alternatively carrying with it a joint forming material into the fresh concrete. The blade descends until it reaches a physical stop, which has been set within the machine. Upon initiation of the downward motion of the blade, the operator can also initiate action by vibrators, which are physically attached to the machine, in case they are needed. The vibration action can be continued while the blade extends, while it is in its most downward position and during retraction. During the time the blade is fully extended should the control joint be formed as a weakened plane, the vibration will also force the segregation of the aggregate particles in the matrix around the blade. Should the control joint be formed by plastic strip insert material, the vibratory action of the blade can be used to improve the bond of the paste to the plastic strip insert material. 
         [0019]    At that time, the operator reverses the direction of the motion of the knife-like blade causing it to retract toward its original position, leaving a formed, weakened plane or alternatively, the plastic joint forming material installed inside the uncured concrete. 
         [0020]    The force required to drive the blade action is provided by actuators driving the part of the machine which holds the knife-like blade. 
         [0021]    The placement of the joint formed from either action by the knife-like blade itself or in the case of the use of a plastic joint forming material, is controlled by the physical attachment of the knife-like blade to the machine during the insertion process so that each and every control joint is identical. 
         [0022]    The entire process to install the control joint requires only seconds to accomplish. It is done at a time when the concrete is being finished and once installed, requires no further attention 
       LIST OF REFERENCE NUMERALS 
       [0023]      10  Left sill 
         [0024]      12  Right sill 
         [0025]      14  Spacer 
         [0026]      16  Blade holder 
         [0027]      18  Left stanchion front 
         [0028]      20  Right stanchion front 
         [0029]      22  Left stanchion rear 
         [0030]      24  Right stanchion rear 
         [0031]      28  Upper beam 
         [0032]      30  Actuator 
         [0033]      32  Attach support 
         [0034]      34  Vibrator 
         [0035]      36  Insertion blade holder 
         [0036]      38  Blade holder guide bar 
         [0037]      40  Blade upper stop 
         [0038]      42  Stripper actuator 
         [0039]      50  Insertion blade 
         [0040]      51  Flat blade 
         [0041]      52  Insertion blade guide 
         [0042]      54  Clip holders 
         [0043]      56  Insertion strip 
         [0044]      58  Support channels 
         [0045]      60  Control panel 
         [0046]      62  Stop 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0047]      FIG. 1  is a side view of the machine but without tubing or wiring being shown. 
           [0048]      FIG. 2  is the end view of  FIG. 1  with minimum detail for clarity 
           [0049]      FIG. 3  is a larger and more detailed section of  FIG. 2 . 
           [0050]      FIG. 4  is a section detail of the left end of  FIG. 1  showing more detail 
           [0051]      FIG. 5  is a top view of  FIG. 4   
           [0052]      FIG. 6  is an enlarged view of the end of the machine showing the relationship of the component parts when the system is ready for activation. 
           [0053]      FIG. 7  shows a view of the assembled insertion blade 
           [0054]      FIG. 8  is an end view of  FIG. 7   
           [0055]      FIG. 9  is a view of the insertion blade with insertion strip attached 
           [0056]      FIG. 10  is a section view of the sills holding the stripper actuators and their association with the insertion blade. 
           [0057]      FIG. 11  shows the relation of the blade position just before installation in the machine. 
           [0058]      FIG. 12  shows the position of the insertion blade in the down position. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0059]    An embodiment of the present invention shall be described in the following with reference to the drawings. 
         [0060]    As shown in  FIGS. 1 through 6 , the machine is a generally rectangular formed structure. It may be built in any desirable length by giving consideration to the structural requirements associated with the chosen length. Sill  10  and Sill  12  are formed so that each has at least a horizontal and a vertical leg. The horizontal leg of each sill forms the footing upon which the machine rests and provides restraint to prevent upward “bulging” from concrete displaced during the insertion. The vertical leg of each sill when spaced a precise distance one from another, form a space into which insertion blade  50  travels when performing the insertion function. 
         [0061]    Spacer  14  is rigidly attached to Sills  10  and  12  and performs two functions. The first of these functions is to hold Sills  10  and  12  precisely spaced one from another. The other is to provide a positioning support upon which Insertion blade  50  rests while being inserted into Blade holder  36 . Spacer  14 , while providing the surface over which Insertion blade  50  slides while being installed in Blade holder  36 , also establishes the vertical location between the sills for the bottom edge of Insertion blade  50 .  FIG. 6  more clearly shows the function of Spacer  14 . The position of Insertion blade  50 , between the vertical legs of Sills  10  and  12 , ensures that the downward motion of Insertion blade  50  can only move directly downward thus assuring a straight control joint. 
         [0062]    Stanchions  18  and  20  at one end and  22  and  24  at the other end of the Sills  10  and  12  are rigidly attached to the end of Sills  10  and  12  and extend vertically while separated by the same precise dimension separating Sills  10  and  12 . An additional clearance channel is formed in the inside face of each of stanchions  18  and  20 , as well as  22  and  24  in a location and of a configuration so as to provide clearance for the Installation of Insertion blade  50  into Blade holder  38  when Blade holder  38  is positioned in its most upward position. 
         [0063]    Beam structure  28  is attached to Stanchions  18  and  20  at one end and  22  and  24  at the other end by conventional methods. At each end of Beam structure  28 , Attach support plate  32  provides universal mounting attachments. Handles for local operation or interface to other machinery may use Attach supports  32 . 
         [0064]    Beam structure  28  is structurally capable of withstanding the loads placed upon it by Actuators  30 , while those actuators are forcing Blade holder  36  with its associated Insertion blade  50  downward into the concrete. Additionally, the attachment of Beam structure  28  to Stanchions  18  and  20 , and  22  and  24  continues to maintain the precise separation between the stanchions. 
         [0065]    Although only two Actuators  30  are shown, as the length of the machine increases, the force required to accomplish the insertion increases and therefore the number and size of Actuators  30  must be matched to the required load. The energy causing the forcing action of Actuators  30  may be from any appropriately sized commercial electrical, pneumatic or hydraulic source. 
         [0066]    Blade holder guide bar  38  is physically attached at each end of Blade holder  36  and is configured to perform several functions. First it ensures that as Blade  50  proceeds downward, Blade holder guide bar  38  moves within the spacing between Stanchions  18  and  20  on one end and  22  and  24  on the other. A second function of Blade holder guide bar  38  is to stop the downward motion at a prescribed distance thus controlling the depth of the insertion. Stop  62  and Blade upper stop  40  is a receptacle into which a shear pin may be inserted. The shear pin is not shown for clarity. Blade holder guide bar  38  is configured such that as it proceeds downward and reaches the location of Stop  62 , the upper section of Blade holder guide bar  38  interferes with stop  62  limiting the travel of insertion blade holder  36 . Stop  62  may be positioned at more than one dimension to provide more than one insertion depth. The third function of Blade holder guide bar  38  is to provide an upper limit for the action of Insertion blade holder  36  in its upward direction. Blade upper stop  40  is positioned such that as Insertion blade guide bar  38  reaches its upper limit of travel, the top of Insertion blade guide bar  38  interferes with Blade upper stop  40  limiting its upward travel. 
         [0067]    Support channels  58  provide structural support for the entire assembly by providing a structural member between Sills  10  and  12 , and Upper beam  28 . Should a longer dimension of the entire machine be configured, more Support channels  58  may be required. Additionally, centrally located Support channels  58  provide mounting means for Control panel  60   
         [0068]    Insertion blade holder  36  is a rectangular formed tube configured with a slot located in the lower face of the tube and extending the entire length of the tube into which Insertion blade  50  is placed. Blade holder guide bar  38  is rigidly attached to the top side at each end of Insertion blade holder  36 . As shown in  FIG. 6 , when Insertion blade holder  36  is in its upward position, it is located so that it is aligned with the cutouts made in stanchions  18 ,  20 ,  21  and  22 . 
         [0069]    Vibrators  34  are mounted rigidly to the upper face of Insertion blade holder  36 . When energized they cause Insertion blade holder  36  and it&#39;s associated Insertion blade  50  to vibrate thus generating the desired realignment of the aggregate within the concrete mixture as insertion blade  50  descends into the concrete mixture. 
         [0070]    Control panel  60  contains the physical interconnects between the required control wiring, tubing, valves, relays and other electrical components. Those skilled the art can easily interconnect the required items to cause the machine to function. Local switching, remote switching or computer may do initialization of the various functions, 
         [0071]    When a control joint is to be formed by using a plastic strip, that strip is mounted on Insertion blade  50  as shown in  FIGS. 6 and 9   
         [0072]    As shown in  FIG. 7 , Insertion blade  50  is made up of flat blade  51  of any desired length attached to which are Insertion blade guides  52 . Insertion blade guide  52  when attached to flat blade  51  position the entire Insertion blade  50  correctly within Insertion blade holder  36 . Also attached to Flat blade  51  are Clip holders  54 . Clip holders  54  are spring material so formed as to press against Flat blade  50  creating a retaining force against Insertion strip  56  when Insertion strip  56  is installed as shown in  FIGS. 6 and 8 . 
         [0073]      FIG. 11  shows Insertion blade  50  with attached Insertion strip  56  installed ready for installation in the machine.  FIG. 12  shows Insertion blade  50  in its most downward position. At this time it would have been inserted into the concrete mixture not shown in the figure. 
         [0074]    When Insertion blade  50  with Insertion strip  56  attached is embedded in the concrete mixture it is required that Insertion strip  56  not be withdrawn when Insertion blade  50  is withdrawn. 
         [0075]    Stripper actuators  42  are mounted in Sills  10  and  12  as shown in cross section in  FIG. 10 . Stripper actuators  42  are linear actuators and when inactivate, rest in the corner of the vertical and horizontal legs of Sills  10  and  12 . When Insertion blade  50  is withdrawn, Stripper actuators  42  are activated causing the pistons of those actuators to extend until they interfere with Insertion blade  50 . That interference is positioned such that it coincides with the upper edge of Insertion strip  56  causing insertion strip  56  to remain in position embedded in the concrete medium while Insertion blade  50  is withdrawn. 
         [0076]    Should a control joint be developed with out the use of insertion strip  56 , Insertion blade  50  would not require clip holders  54 . Nor would stepper actuators  42  perform any function. Their presence causes no deleterious actions. 
       OPERATION OF THE INVENTION 
       [0077]    With concrete having been placed into conventional concrete forms or slip form configuration, and while it is still fresh, the Concrete Joint Inserter is moved to the location where a control joint is to be formed. The Joint inserter is set across the expanse of concrete spanning the distance between the edges of the concrete placement. When the joint insertion tool is in position for its use, Sills  10  and  12  are either resting on the forms or held in position parallel to the surface of the concrete placement. 
         [0078]    A shear pin is installed in the appropriate location for Stop  62  which sets the depth of insertion of the control joint to be formed. 
         [0079]    Insertion blade  50  is selected of a length that will span the distance between the edges of the placement. 
         [0080]    Should the ensuing control joint use Insertion strip  56  to form the weakened plane, Insertion strip  56  is attached to Insertion blade  50  using Clip holders  54 . Insertion blade  50  with attached Insertion strip  54  is installed in the machine. 
         [0081]    Should the ensuing control joint be formed without the use of insertion strip,  54 , only Insertion blade  50  need be installed. 
         [0082]    Appropriate power, electrical and/or pneumatic or hydraulic, is attached. 
         [0083]    Power is initiated to Actuators  30  in the downward direction and to Vibrators  34 . Power is continuously applied until Insertion blade  50  reaches the insertion depth established by stop  62 . While Vibrators  34  continue to operate, Actuators  30  are powered in the upward direction. At the same time Stripper actuators  42  are energized and their pistons extend to interfere with Insertion blade  50 . Should Insertion strip  56  have been installed it would now be left in the concrete mixture having been stripped off by the blade by fluid resistance of the concrete mixture and due to the Stripper actuators  42 . Had no Insertion strip  56  have been used, the withdrawal of Insertion blade  50  leaves the aggregate segregated and with cementitious material filling the void left by retreating Insertion blade  50 . Actuators  30  continue the upward motion until Upper stop  40  is reached at which time power to Actuators  30  and Vibrators  34  may be terminated. The cycle is now complete and no further action is required to service the control joint now formed in the concrete