Patent Application
20070166104
The invention relates generally to concrete strike-off tools and methods, and more particularly to a portable apparatus that can be used to define a form for concrete strike-off operations.
In concrete slab construction, the manual striking off of wet or plastic concrete is a labor intensive process that generally consists of three steps, the first of which will differ according to the desired elevation of the finished concrete surface. For example, if the finished surface is intended to parallel the base over which the concrete is being placed (thereby resulting in a slab of constant thickness), then the wet concrete surface at various small isolated spots is first struck off to its intended finished elevation by measuring up from the base using a gage stick equal in length to the desired finished slab thickness. If, however, the finished surface is not necessarily intended to be constant thickness, but is instead intended merely to be planar, then the wet concrete surface at various small isolated spots is first struck off to its intended finished elevation by using an optical or laser level and grade stick to define the desired plane. In both of these above-described cases, the small isolated reference spots that are initially formed in the wet concrete surface are termed “wet pads”. To facilitate subsequent strike-off operations, the distances between adjacent wet pads are kept somewhat shorter than the length of the straightedge that is to be used to strike off the bulk of the concrete.
The second step in a manual strike-off operation involves using the straightedge and two adjacent wet pads as elevation references. The concrete between the wet pads is struck off to create a narrow, elongated section of at-grade concrete that is termed a “wet screed”. Again, to facilitate subsequent strike-off operations, the wet screeds are generally made to parallel one another at spacings somewhat shorter than the length of the straightedge.
The last step in a manual strike-off operation involves using the straightedge and two adjacent wet screeds as elevation references to strike off the concrete between the wet screeds to grade. However, owing to the plastic, unstable character of the wet pads and wet screeds that are used to control the elevation of the straightedge, the finished surfaces produced by this so-called “wet screed” method of concrete slab construction typically exhibit poor conformity to the desired grade.
Accordingly, it is an object of the present invention to provide an apparatus that simplifies the positioning and establishment of a temporary and rigid reference form to control the elevation of a straightedge as it is used to strike-off a concrete slab either to a constant thickness or a plane.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a form for concrete strike-off is provided. A pan adapted to float on a plastic concrete surface has a rigid straightedge coupled thereto. More specifically, the straightedge has first and second ends opposing one another along a longitudinal dimension thereof. The first end is adjustably coupled to the pan such that the first end can at least be rotated relative to the pan. A support is coupled to the second end of the straightedge with the straightedge thereby defining a reference elevation for concrete strike-off operations. Each such apparatus can be used by itself or in concert with a multiplicity thereof to set temporary forms for a concrete strike-off operation. Each apparatus operates independently to set a form at, or parallel to, the locally desired grade of the finished concrete.
Other objects, features and advantages of the present invention will become apparent upon reference to the following description of the preferred embodiments and to the drawings, wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings and wherein:
Referring now to the drawings, and more particularly to
Apparatus 10 includes three main assemblies that are coupled to one another. The assemblies are a pan assembly 20, a form assembly 30, and a support assembly 40. In general, pan assembly 20 floats on finished surface 104 while providing the means to set the elevation of one end of form assembly 30. Support assembly 40 rests on underlying base structure 100 while providing the means to set the elevation of another end of form assembly 30 by, for example, being extensible and retractable in length as in the illustrated embodiment. Form assembly 30 defines a finished surface reference form for the concrete being struck-off. After reading the ensuing description of the illustrated embodiment and the use thereof, one of ordinary skill in the art will readily appreciate that the functions of each of pan assembly 20, form assembly 30, and support assembly 40 could be realized by a variety of constructions without departing from the scope of the present invention. Accordingly, it is to be understood that the illustrated embodiment is presented as a non-limiting example of the present invention.
In the illustrated embodiment, pan assembly 20 includes a pan 21 having a flat bottom 21A that is large enough so that pan assembly 20 can float on finished surface 104. For reasons that will become clearer below, some or all of the edges of pan 21 can be beveled as indicated by numeral 21B to facilitate the movement of pan 21 on finished surface 104. Attached to pan 21 is post 22. More specifically, in the illustrated embodiment, post 22 is connected to pan 21 via a pivot or hinge 23 so that post 22 is freely rotatable thereabout (as indicated by two-headed arrow 24) in a plane that is substantially perpendicular to pan 21. Post 22 is threaded along some or all of the length thereof (as indicated at 25) to threadably engage top and bottom nuts 26 and 27, respectively.
Form assembly 30 includes a long rigid bar 31 having a top 31A defining a finished surface reference form for concrete strike-off. Thus, as will typically be the case, top 31A defines a straight edge. However, the present invention is not so limited. That is, without departing from the scope of the present invention, rigid bar 31 can be configured in a variety of ways (e.g., a variety of different cross-sectional shapes) such that some element thereof other than it's top serves as the finished surface reference form.
One longitudinal end 31B of bar 31 is coupled to pan assembly 20 while the other longitudinal end 31C of bar 31 is coupled to support assembly 40. In the illustrated embodiment, bar 31 is coupled to pan assembly 20 by a rigid L-shaped or “gooseneck” bracket 32 rigidly and/or fixedly coupled to end 31B. A hole 32A formed in an outboard end of bracket 32 is sized to slip over post 22 as shown with nuts 26 and 27 being used to capture bracket 32 therebetween as will be explained further below.
End 31C of bar 31 is coupled to support assembly 40 in any of a variety of ways that provide for vertical movement (relative to desired grade A-A) of end 31C as support assembly 40 extends/retracts. For example, a vertical extension member 31D can be provided on bar 31 with member 31D being coupled to support assembly 40 at a coupling point 33. The use of vertical extension member 31D keeps the vertically movable portion of support assembly 40 out of the wet concrete 102.
In the illustrated embodiment, support assembly 40 includes an open-ended outer sleeve 41 and a rod 42 that passes through the central portion of sleeve 41 and extends from either end thereof. Rod 42 is threaded at least partially therealong at 43 for threaded cooperation with mating threads 44 in sleeve 41. As a result, sleeve 41 and rod 42 share a common longitudinal axis referenced by dashed line 45. When rod 42 is rotated about longitudinal axis 45 while sleeve 41 is maintained in a non-rotating relationship, sleeve 41 moves towards one end or the other of rod 42 thereby causing the lengthening or shortening of support assembly 40.
Sleeve 41 is coupled to bar 31 via vertical extension member 31D. For example, sleeve 41 can incorporate an extension bracket 41A that connects to member 31D at coupling point 33. Although not a requirement of the present invention, coupling point 33 could be realized by a hinge or pivot that provides for free rotation thereabout as indicated by two headed arrow 34. The plane of rotation 34 can be aligned with that of the plane of rotation 24.
One end of rod 42 will be positioned on underlying base structure 100. Accordingly, this end can have a swiveling foot or pad 46 coupled thereto to engage support 100 in a non-slip fashion. The opposing longitudinal end of rod 42 can have a hand crank 47 coupled thereto to facilitate the manual turning of rod 42 about longitudinal axis 45.
As will be explained further below, use of apparatus 10 involves an initial set-up with both ends 31B and 31C being set at a desired elevation, and subsequent checks of the elevation of end 31C each time apparatus 10 is moved. The elevation setting/checking of end 31C can be accomplished with a variety of instruments well known in the art. For example, as illustrated in
Another option is illustrated in
Apparatus 10 can be used by itself or in groups of two or more to set a temporary form for concrete strike-off. Use of apparatus 10 begins by first finishing a wet pad of plastic concrete to the desired grade/elevation (e.g., a finished patch at grade A-A referenced in
As mentioned above, one or more of apparatus 10 can be used in a concrete strike-off operation. Accordingly,
In
A similar process is used when two or more of apparatus 10 are used. For example,
As mentioned above, the present invention is not limited to the particular embodiment just described. For example, the form of the present invention could be achieved in a variety of ways without departing from the scope of the present invention. One such approach is illustrated in
The present invention can be further adapted/simplified for cases where a finished concrete surface will be of constant thickness in all uses thereof. For example,
a floating pan 71,
an L-shaped or “goose-neck” bracket 73 coupled to pan 71 at a position 72 where position 72 is representative of either (i) a fixed coupling between pan 71 and bracket 73 such that relative movement therebetween is prevented, or (ii) a coupling that provides for relative movement between pan 71 and bracket 73, e.g., a hinge that permits rotation of bracket 73 about position 72 in a plane as indicated by two-headed arrow 74, a swivel that permits rotation of bracket 73 about position 72 in a multiplicity of planes, etc.,
a rigid bar 75 fixedly coupled on one end thereof to bracket 73 with the top 75A of bar 75 being aligned with the bottom 71A of pan 71, and
a rigid support such as a post or pole 76 to which bar 75 is fixedly coupled on the other end thereof such that the distance D between top 75A and the bottom 76A of pole 76 is equal to the desired concrete thickness.
In this configuration, apparatus 70 can be used to strike-off wet concrete to a constant thickness D once an initial wet pad of concrete at thickness D has been established for the initial placement of pan 71.
Still another embodiment of the present invention is illustrated in
two pans 81 and 82, each of which is capable of floating on wet concrete,
gooseneck brackets 83 and 84 coupled to pans 81 and 82, respectively, and
a rigid bar 85 fixedly coupled on one end thereof to bracket 83 and on the other end thereof to bracket 84 with the top 85A of bar 85 being aligned with the bottoms of pans 81 and 82.
Thus, in this embodiment, pans 81 and 82 define completely floating supports for bar 85.
Similar to the
In each of the above-described embodiments, the apparatus's rigid bar defines a reference elevation that is the actual concrete strike-off elevation. However, the present invention is not so limited as the rigid bar could be suspended over the wet concrete with the bar defining a reference elevation that is parallel to a concrete strike-off elevation. That is, the rigid bar could be supported at either end thereof (e.g., by one floating pan and a fixed-length or extendable-length post, by two floating pans, etc.) such that the entire rigid bar stays above the wet concrete. The end of the strike-off straightedge could then be equipped with a guide that would ride along an element of the suspended bar, e.g., the bar's top. One realization of this embodiment is illustrated by way of example in
The advantages of the present invention are numerous. The apparatus can be used by itself or in concert with a multiplicity thereof to set temporary forms for a concrete strike-off operation. Since each such apparatus operates independently, each is set to provide a form at the locally desired finish grade. Since nothing needs to be extracted from a finished region, the apparatus maintains the integrity of a struck-off surface. The present method of partially or fully floating supports for a rigid bar that defines a reference elevation for concrete strike-off operations provides accuracy, portability, and repeatability attributes that are not possible with current concrete strike-off systems/methods.
Although the invention has been described relative to specific embodiments thereof, there are numerous other variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described.
