Abstract:
Method and product for the forming of contraction joints in the end face of poured concrete structures that includes a blade-like insert of selective profile configuration corresponding to the profile surface of a form board to be utilized for shaping the end face when poured. The insert is attachable to the profile surface of the form board and includes a blade member extending laterally away from the profile surface to produce a contraction joint in the end face when cured.

Description:
FIELD OF THE INVENTION 
     The field of art to which the invention relates comprises forming of a contraction joint in concrete poured facings such as the cantilevered nose cap of a swimming pool. 
     BACKGROUND OF THE INVENTION 
     Concrete decking placed around swimming pools is generally on the order of about four inch thickness divided into six foot by six foot bays to prevent adverse, unsightly cracking. This is effected by introducing a wecond plain system comprising placement of a contraction joint which penetrates the concrete when wet through one-third of its thickness. The resulting benefit is that the concrete tends to be weaker in and about the straight lines representing the contraction joint. 
     It is recognized that concrete when poured begins to hydrate and become chemically hot, so that during the first few hours of setting, the decking is at its most expanded state. As cooling begins, the concrete begins to contract and the wecond plain lines allow for contraction. The shrinkage cracks remain invisible beneath the contraction joint. By also extending the joint around the cantilevered face of the decking, the contraction crack thereat occurs unnoticed behind the nose cap. 
     Prior to about 1958 when plastic contraction joints were first introduced to the trade, concrete workers utilized a deep jointer displaced across the top of the freshly poured concrete to form the contraction joint. This jointer was attached to a long handle and produced a joint  1  to 1½ inches deep in straight lines across the concrete surface causing a wecond plain that allowed for concrete shrinkage. This method is still widely used throughout the concrete industry on, for example, sidewalks, wall caps, steps and anywhere controlled cracking of concrete is required. 
     DESCRIPTION OF THE PRIOR ART 
     Contraction joints for concrete and particularly in vertically oriented facings such as the curved cantilevered nose of a poured concrete pool decking has long been effected by use of either precast nose sections or by the use of a cutting tool after the concrete has set. While functioning well and affording a pleasing appearance, the cost of grooving by hand typically has run about $8.60 per linear foot while utilizing pre-cast units has run about $21.00 per linear foot. 
     While the foregoing costs have been recognized as somewhat exorbitant, it has not been known heretofore how they can be significantly reduced. 
     OBJECTS OF THE INVENTION 
     An object of the invention is to provide novel product and method for effecting a contraction joint on the face of concrete structures. 
     It is a further object of the invention to effect the previous object with a product and method in which the contraction joint can be formed during the pouring and curing of the concrete. 
     It is a still further object of the invention to effect the previous objects at a substantially lower cost than has been possible by techniques utilized heretofore. 
     SUMMARY OF THE INVENTION 
     This invention relates to the formation of contraction joints in concrete structures. More specifically, the invention relates to forming contraction joints in the face of concrete structures such as in the nose cap of swimming pool decking and at a substantially lower cost compared to the current costs of pre-cast units or hand cutting thereof. 
     For achieving the foregoing, an available form of a configured form board is selected to shape the face of the concrete when poured and in accordance herewith, is provided with a plurality of longitudinally spaced blade-like inserts removably secured on the interior of the form board. With the form board in place to receive the poured aggregate, the inserts laterally extend forward of the form board into the face-path of the concrete. Being that the blades penetrate the concrete, subsequent removal of the insert along with removal of the form board after the concrete has cured, results in a cast formation of a contraction joint thereat. Yet, with the inserts still in place, a cement finishing person using a straight edge for alignment, can rectilinearly advance a deep joint tool successively from each bladed insert toward the opposite side in order to effect continuity of the contraction joint from on the vertical edge to the adjoining horizontal surface. 
     Each insert is constructed of a suitable plastic composition such as polyethylene, PVC, etc. and can conveniently be formed by injection molding. It can be formed in a variety of different configurations to fit each and every form board profile. As a result, the cost of forming the contraction joint is typically reduced to less than about ten cents per linear foot, that can be appreciated, is significantly less than the cost of either pre-cast units or hand cutting the concrete face as noted supra. 
     The end result is that the poured aggregate, such as the wall cap of swimming pool decking forms a pre-cast appearance at a significantly lower cost than the pre-cast units or a hand carving of the prior art and can be utilized on any concrete face with which a form board is utilized. The virtues thereof can be readily appreciated by those skilled in the art. 
     The above noted features and advantages of the invention as well as other superior aspects thereof will be further appreciated by those skilled in the art upon reading the detailed description which follows in conjunction with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a prior art isometric view of a poured concrete wall cap in preparation of being formed; 
     FIG. 2 is an isometric view of the wall of FIG. 1 onto which a wall cap is to be formed in accordance with the invention hereof; 
     FIG. 3 illustrates the poured wall cap of FIG. 2; 
     FIG. 4 illustrates the finished wall cap of FIG. 2; 
     FIG. 5 is a sectional elevation for forming contraction joints in the nose end of swimming pool decking in accordance herewith; 
     FIG. 6 illustrates a first profile form board supporting a first profile blade-insert in accordance herewith; 
     FIG. 7 is a front elevation of FIG. 6; 
     FIG. 8 illustrates a second profile form board supporting a second profile blade-insert in accordance herewith; 
     FIG. 9 is a front elevation of FIG. 8; and 
     FIGS. 10-12 illustrate various other form board profiles supporting blade-inserts of corresponding profiles in accordance herewith. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the description which follows, like parts are marked throughout the specification and drawings with the same reference numerals respectively. The drawing figures are not necessarily to scale and in certain views, proportions may have been exaggerated for purposes of clarity. 
     Referring now to FIG. 1, there is illustrated a prior art construction of a wall  10  as might be utilized, for example, for patios or the like. Included is a poured concrete wall cap  12  disposed utilizing opposite form boards  14  and  16  of a selected facing profile  18  to form perimeter face  20 . Contraction joints  22  have been formed in the horizontal surface of cap  12  using a deep jointer (not shown). Shown in phantom, is a vertical contraction joint  24  to be formed subsequently in face  20  after the concrete has cured and the form board  14  removed. Form boards  14  and  16  are of a type commercially available and generally are comprised of styrofoam as disclosed, for example, in U.S. Pat. No. 4,967,424. The selected profile surface  18  is available in a variety of different configurations as will be described more fully below. 
     Referring now to FIGS. 2-4, there is illustrated forming the wall cap  12  on wall  10  in accordance with the invention to include contraction joints  24  in face  20  of the finished wall cap. For achieving that result, there is provided a plurality of oppositely placed blade-like inserts  26  attached and conforming to the interior profile surface  18  of each form board  14  and  16  at predetermined longitudinal spacings. The inserts are each formed of a plastic composition such as polyethylene, PVC, etc. that are injection molded to conform with the profile of the form board on which they are to be utilized. Each insert is configured in a T-shaped cross-section having a back wall  30  on the order of up to about one inch in width for engaging and attaching against the profile surface  18  of the form board. Laterally extending integral from the back wall is of a centrally located, integral blade  32  having a pre-determined profile width “x” (FIG. 5) on the order of about ⅝-1 inches and a thickness “Y” (FIG. 7) of about ¼ inch. A radius  48  along each corner of distal edge  50  on the order of about {fraction (3/32)}-1 inch provides draft for removing the blade without disturbing the set aggregate. Each of the inserts are secured to the surface profile  18  of the form board by the use of integral prongs  34  (FIGS. 6 &amp; 8) or other suitable nail-like fasteners known in the art. 
     With the form boards in place at the pour site and after pouring the aggregate  36  to form wall cap  12  as best seen in FIG. 3, the concrete is permitted to cure after which the form boards  14  and  16  along with inserts  26  are removed. This results in the finished wall cap  12 , as best seen in FIG. 4, that includes the contraction joints  24  pre-cast at predetermined intervals into the cap aggregate at the location of removed inserts  26 . 
     As shown in FIG. 5, a poured concrete wall  38  is illustrated for an in-ground swimming pool on which face tile  40  has been applied in a well known manner. Form board  14  is secured to the face tile via double-faced adhesive tape  42  and defines a surface profile  18  for nose  46  and to which a plurality of blade-inserts  26  are attached. After pouring and curing of the cantilevered decking  44 , form board  14  with inserts  26  are removed forming the nose  46  to include surface profile  18  along with the longitudinally spaced contraction joints  24  as before. 
     As shown in FIGS. 6-12, blade-insert  26  can be utilized on a variety of form boards  14  having selectively different surface profiles of matching configurations  18 . The form board embodiment shown in FIGS. 6 &amp; 7 is commercially marketed as a “Capstone 350”; the form board embodiment of FIGS. 8 &amp; 9 is commercially marketed as a “Mini-Cap 300” while the form boards of FIGS. 10,  11  &amp;  12  are commercially marketed as “Regular 360”; “O-G pattern 400” and “O-G pattern 600” respectively. The form board of FIG. 8 is generally utilized on planter retaining walls while the profile form of FIG. 11 is normally used on patio walls, window ledges and top fascia of Spanish-type buildings. The form profile configuration of FIG. 12 is normally used to cap columns that rise above a block wall at twenty foot intervals and also to cap Spanish-type parapet walls. 
     The various profile configurations above exemplify the numerous form board profiles with which the inserts  26  hereof may be utilized. Each insert includes a laterally outward extending blade  32  for forming contraction joints in the poured facing of various concrete structures. Obviously, other shapes and configurations can be readily adapted similarly. 
     By the above description there is disclosed novel product and method for effecting contraction joints in the poured facing of concrete structures. Being relatively inexpensive to provide and utilize, the method and product hereof afford distinct advantages over the formation of such contraction joints in the manner of the prior art without any sacrifice in aesthetic appearance. By means hereof there is afforded a simple yet inexpensive method and product for effecting contraction joints in the end-face of poured concrete structures. 
     Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specification shall be interpreted as illustrative and not in a limiting sense.