Patent Publication Number: US-2015082738-A1

Title: Joint strip and terrazzo surface using an improved joint strip

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional patent application Ser. No. 61/880,558 filed Sep. 20, 2013, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The present disclosure relates to an improved joint strip and a method of making a terrazzo surface using the improved joint strip. 
     Referring to PRIOR ART  FIG. 1 , terrazzo surfaces, e.g. floors, use a poured or precast composite material that is formed in a desired pattern and with desired additional materials, e.g., decorative stones, marble, glass, etc., in a binder. Terrazzo is cured, ground and polished to a smooth surface. 
     A terrazzo floor usually begins with a base, or foundation that is three to four inches deep, created using forms. Above that might be an inch partially wet sandy concrete, in which metal divider strips are placed to form joints in the terrazzo. The divider strips may be placed and shaped as desired for the structure pattern (e.g., providing a curved joint and/or defining divides between different terrazzo regions). The divider strips themselves can be bent/shaped on-site to define the surface pattern, or they may be pre-shaped. 
     Colored or varied materials may be used on an upper surface in the binder for decoration. A weighted roller is then used over the surface to level materials. Other binders may also be used, e.g., polymer-based binders including polyester and vinyl ester resins or epoxy resins. When the terrazzo is dried/cured, it is ground with a heavy grinder before polishing and sealing. 
     PRIOR ART  FIG. 1  illustrates an exemplary terrazzo floor, shown generally at  10 . Three distinct terrazzo patterns are shown at  12 ,  14  and  16 , with the patterns separated by joints  17 . It can be seen that terrazzo patterns  12  use a smaller stone pattern, terrazzo pattern  14  uses a tiled pattern, and terrazzo pattern  16  uses a larger smoothed stone pattern. Joint strips ( 18  in PRIOR ART  FIGS. 5-7 ) may be formed on site using opposing strip pieces that are arranged in a desired pattern, as described above, or may be pre-formed according to the desired pattern. 
     Referring now to PRIOR ART  FIGS. 2-4 , each side of a joint strip ( 20 ,  28 ), which is used to define the joint  17 , is typically formed from a piece of divider strip  20  having a bottom portion  22  and a wall portion  24 . The bottom portion includes a plurality of apertures  26 , which may be used to secure the joint strip in place. 
     Referring now to PRIOR ART  FIGS. 5-6 , opposing strip pieces  20  and  28  define the joint channel  30  of a joint strip  18 . These joint strips  18  may be formed by separately laying down opposing strips  20 ,  28  (“raw strips”) with the calculated spacing and desired geometry on-site during formation of the surface. 
     Alternatively, joint strips  18  may be pre-assembled with a predetermined spacing and geometry (shape, length, etc.) prior to installation. The pre-made strips/joints  18  may be pre-assembled using a rubber or elastomeric filler to adhere the opposing strips  20 ,  28  together. PRIOR ART  FIG. 7  illustrates use of such filler  32  within channel  30  for a pre-assembled joint strip  18 . 
     Either solution, described above, provides consistent problems in the field, such as failure to perform and excessive labor to place and fill gaps between the strips. Further, pre-assembled joints suffer from expansion problems during manufacture of the surface, where components tend to pull away during manufacture and cure. Indeed, strips pre-made with a rubber filler have not been recommended by the NTMA (National Terrazzo and Mosaic Association) for those reasons. 
     What is needed in the art are improved joint and terrazzo manufacturing procedure that avoids the expense and failure problems prevalent in the field. 
     BRIEF SUMMARY OF THE INVENTION 
     The above discussed and other drawbacks and deficiencies are overcome or alleviated by the present improved joint strip and method for constructing a terrazzo surface, including use of a joint strip, comprising opposing strip portions having upper wall surfaces that are joined by a solid upper joint strip channel wall. In exemplary embodiments, such improved joint strip may be installed during a terrazzo surface manufacturing procedure, with the solid upper joint strip channel wall protecting the integrity of the channel geometry and shielding the channel from debris during manufacture. During the grinding procedure, the solid upper joint strip channel wall may be ground away to reveal a joint channel having optimal geometry. In exemplary embodiments, the resulting exposed joint channel (or “gap”) spans ¼ inch (which is recommended by the NTMA and epoxy manufacturers). 
     In other exemplary embodiments, the joint channel may then be filled with an elastomeric material or other material, as determined by the flooring contractor. Various other exemplary embodiments are also contemplated herein, e.g., a “backer rod” filler, a plastic rod filler, a wood filler, a neoprene/rubber filler, or the like (any removable filler), that is removed after the grinding process (including grinding off of the upper joint strip channel wall), with the joint channel being filled with required filler material thereafter. In other exemplary embodiments, the joint strip channel under the upper joint strip channel wall is filled with an elastomeric filler, with the joint being considered finished after grinding off of the upper joint strip channel wall and sealing of the surface. 
     The above-discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the figures wherein like elements are numbered alike in the several figures: 
       PRIOR ART  FIG. 1  illustrates an exemplary terrazzo floor; 
       PRIOR ART  FIG. 2  illustrates a perspective view of a joint strip portion used in the conventional manufacture of a joint for a terrazzo floor; 
       PRIOR ART  FIG. 3  illustrates a top elevation view of the joint strip portion of PRIOR ART  FIG. 2 ; 
       PRIOR ART  FIG. 4  illustrates a side elevation view of the joint strip portion of PRIOR ART  FIG. 2 ; 
       PRIOR ART  FIG. 5  illustrates a perspective view of an on-site assembled joint strip comprising separate opposing strips; 
       PRIOR ART  FIG. 6  illustrates a top elevation view of the on-site assembled joint strip of PRIOR ART  FIG. 5 ; 
       PRIOR ART  FIG. 7  illustrates a side elevation view of a pre-assembled joint strip, using a filler for adhesion of opposing strips; 
         FIG. 8  illustrates a perspective view of an exemplary joint strip of the present invention including an upper joint channel wall; 
         FIG. 9  illustrates a top elevation view of the exemplary joint strip of  FIG. 8 ; 
         FIG. 10  illustrates a side elevation view of the exemplary joint strip of  FIG. 8 ; and 
         FIG. 11  illustrates a side elevation view of the exemplary joint strip of  FIG. 10  with additional filler provided in the joint channel before installation. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As was noted above, the present disclosure relates to an improved joint strip and method for constructing a terrazzo surface using such improved joint strip for an expansion or control joint, the improved joint strip comprising opposing strip portions having upper wall surfaces that are joined by a solid upper joint strip channel wall. 
     In exemplary embodiments, such improved joint strip may be installed during a terrazzo surface manufacturing procedure, with the solid upper joint strip channel wall protecting the integrity of the channel geometry and shielding the channel from debris during manufacture. During the grinding procedure, the solid upper joint strip channel wall may be ground away to reveal a joint channel having optimal geometry. In exemplary embodiments, the resulting exposed joint channel (or “gap”) spans ¼ inch (which is recommended by the NTMA and epoxy manufacturers). 
     Referring now to  FIG. 8 , an exemplary pre-formed joint strip is illustrated generally at  40 . The joint  40  includes opposing side wall portions  42 ,  44  joined to opposing base portions  46 ,  48 . A pre-formed joint strip channel  50  is defined by opposing side wall portions  42 ,  44  and an upper joint strip channel wall  52 . During a terrazzo surface (floor or other surface) manufacture, the upper joint strip channel wall  52  is configured to be ground away during the grinding of the surface (which is a typical pre-finishing procedure for terrazzo surfaces). 
     In other exemplary embodiments, after grinding away of the upper joint strip channel wall  52 , the joint channel may then be filled with an elastomeric material or other material, as determined by the flooring contractor. Various other exemplary embodiments are also contemplated herein, e.g., a “backer rod” filler, a plastic rod filler, a wood filler, a neoprene/rubber filler, or the like (any removable filler), may be pre-installed in the joint strip channel  50  and removed after the grinding process (including grinding off of the upper joint channel wall), with the joint channel  50  being filled with required filler material thereafter. In other exemplary embodiments, the joint strip channel  50  under the upper joint strip channel wall is pre-filled with an elastomeric filler (see  FIG. 11 , which shows a pre-filled joint strip channel), with the joint being considered finished after grinding off of the upper joint strip channel wall and sealing of the surface. 
     Exemplary joint strip materials include zinc, aluminum, brass and stainless steel, among others. 
     Also, while any geometry, thicknesses, depths or gaps are contemplated, an exemplary embodiment contemplates thicknesses between about 0.001 and 0.5 inches, depths between about 0.1 and 3 inches and gaps between ⅛ and 3 inches. Varying depths may account for terrazzo surface depths to allow for proper clearance of the upper joint strip channel wall for grinding during processing of the surface. Exemplary available depths may include standard depths, e.g., ⅜ inch, ½ inch, etc., or they may be made to order. Also, the widths may vary, though an exemplary embodiment contemplates 1.2 inches to accommodate for gap an exemplary ¼ inch gap width and for opposing bases that allow for ¼ inch apertures to secure the joint strip in place. 
     While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.