Patent Publication Number: US-6709194-B1

Title: Apparatus for screeding concrete and other materials

Description:
TECHNICAL FIELD 
     This invention relates to apparatus for screeding concrete and other materials. The apparatus is portable and may be used, for example, to smooth the surfaces of large concrete slabs. This is accomplished without penetrating plastic sheets or other vapor barriers commonly deployed between the ground and slab. 
     BACKGROUND OF THE INVENTION 
     The use of screeds for leveling or smoothing concrete and other materials is well known, screeds dating back many decades, if not centuries. Typically, when screeding large slabs, screed stakes and saddles have been employed to mount lumber or other elongated screed guide members to maintain them at a desired height and orientation. This not only is time consuming, but the technique has other disadvantages as well. When stakes are employed, vapor barrier sheets upon which the slabs often are formed are penetrated by the stakes, creating breaches in the vapor or moisture barriers which can have adverse effects. 
     DISCLOSURE OF INVENTION 
     The present invention relates to apparatus for screeding concrete and other materials which is readily positionable in place and can quickly be adjusted to position an elongated screed guide associated therewith at the desired height and orientation. Furthermore, the apparatus will not pierce plastic sheets or other types of vapor barriers and degrade their performance. 
     The apparatus includes a primary support positionable on a surface to extend upwardly therefrom. 
     A secondary support is adjustably mounted on the primary support for selective up or down movement relative thereto, the secondary support for supporting an elongated screed guide member. 
     The apparatus also includes adjustment mechanism operatively associated with the primary support and the secondary support to adjust the position of the secondary support on the primary support to selectively move the secondary support and any elongated screed guide member supported thereby toward or away from the surface. 
    
    
     Other features, advantages and objects of the present invention will become apparent with reference to the following description and accompanying drawings. 
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a perspective, elevational view of apparatus constructed in accordance with the teachings of the present invention; 
     FIG. 2 is a front, elevational view of the apparatus; 
     FIG. 3 is a side, elevational view of the apparatus, showing alternative positions assumed by a secondary support employed in the apparatus by means of solid and dash lines; 
     FIG. 4 is a perspective view illustrating an elongated wooden screed guide member being supported at two locations by two devices apparatus constructed in accordance with the teachings of the present invention; 
     FIG. 5 is a greatly enlarged, detail, elevational view illustrating a surface engaging support pad of the apparatus positioned on a vapor barrier sheet disposed on the ground; 
     FIG. 6 is a view similar to FIG. 5, but illustrating the surface engaging support pad positioned directly upon metal decking employed to support a slab of concrete; and 
     FIG. 7 is an exploded, perspective view of components of the apparatus. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Referring now to the drawings, a preferred form of apparatus  10  constructed in accordance with the teachings of the present invention is illustrated. Apparatus  10  includes a primary support  12  positionable on a surface to extend upwardly therefrom. In FIG. 4 two units of apparatus  10  are illustrated positioned on a vapor barrier sheet  14  disposed on the ground. FIG. 5 shows a portion of the lower end of the primary support  12  of one of the devices positioned on the vapor barrier sheet  14 . 
     The apparatus  10  also includes a secondary support  16  adjustably mounted on the primary support  12  for selective up or down movement relative thereto. FIG. 3 illustrates the secondary support  16  in two representative alternative positions shown in solid and dash lines. 
     The primary support  12  comprises a framework including a pair of spaced, elongated, substantially vertically oriented framework elements  18  which may, for example, be steel tubing. A framework cross-piece  20  extends between the framework elements  18  and includes sleeves  22  slidably receiving the framework elements  18 . Cross-piece locks in the form of lock screws  24  are threadedly engaged with the sleeves  22  and are employed to selectively lock the framework cross-piece  20  against movement relative to the framework elements  18 . 
     Disposed at the bottom ends of the elongated, substantially vertically oriented framework elements  18  are surface engaging support pads  26 . These support pads  26  have smooth bottoms and are utilized to support the apparatus and disperse downwardly directed forces exerted by the framework elements  18  on the surface on which the apparatus is positioned. 
     When this surface is a plastic sheet or other type of liquid vapor sheet, the dispersion of forces greatly reduces the possibility of punctures in the vapor barrier sheet occurring through use and placement of the apparatus. In the arrangement illustrated, the support pads  26  are releasably attached to the framework elements  18  by lock screws. 
     The secondary support  16  extends between framework elements  18  and is selectively slidably movable along the framework elements. The secondary support  16  includes tubular-shaped guides  30  defining guide openings slidably receiving the framework elements  18 . Secondary support locks in the form of lock screws  32  threadedly engaged with the guides  30  are provided to move into or out of locking engagement with the framework elements to either prevent or allow slidable movement between the secondary support and the primary support. 
     The secondary support  16  includes an open ended receptacle  40  in the form of a channel having a rectangular-shaped cross-sectional configuration. The receptacle  40  is located between the framework elements  18  and is releasably receiving an elongated screeded guide member such as board  42  shown in FIG. 4 Lock screws  44  are threaded engaged with the receptacle  40  and can be moved in or out of the interior of the receptacle to lock the board  42  in fixed position relative to receptacle  40 . 
     A nut is welded or otherwise affixed to the upper surface of framework cross-piece  20  and threadedly receives a threaded shaft  52  which extends through the cross-piece and downwardly therefrom. The lower end of the threaded rod  52  passes through an aperture formed in a bracket  54  welded or otherwise secured to the top of receptacle  40 . A nut  56  is positioned in the space between the receptacle and the top portion of the bracket  54  and threadedly engaged with the bottom of the threaded rod  52 . The nut  56  is fixed against movement relative to the threaded rod by a lock pin  60  extending into a hole  62  formed in nut  56  and an aligned hole  64  formed in the lower end of the threaded rod  52 . 
     A manually graspable handle  70  is secured to the top of threaded rod  52 . Rotation of handle  70  will cause the secondary support  16  and any elongated screed guide member positioned in receptacle  40  to move up or down, that is toward or away from the surface on which the apparatus is positioned. Of course, this movement can only take place when lock screws  32  have been loosened. Once the secondary support  16  and board or other elongated screed guide member have been correctly positioned, the lock screws  32  are tightened. It will be appreciated that this adjustability feature and the adjustability of framework cross-piece  20  relative to framework elements  18  provide for a large range over which an elongated screed guide member supported by the apparatus may be positioned in a highly stable manner. The apparatus  10  may be employed alone or in conjunction with another apparatus of like construction as shown in FIG. 4. A laser system  80  of any suitable known construction may be employed to properly place and orient the board or other elongated screed guide member. 
     FIG. 6 is a view similar to FIG. 5, but showing the apparatus positioned on a metal deck  90  on which a slab is to be formed.