Patent Application
20190186137
Not Applicable
Not Applicable
The present invention generally relates to the art of concrete construction, and more particularly to a device for facilitating the placement of slip dowel rods within a concrete slab.
In the art of concrete construction, it is commonplace to form “cold joints” between two or more poured concrete slabs. Such cold joints frequently become uneven or buckled due to normal thermal expansion and contraction of the concrete and/or compaction of the underlying soil caused by inadequate substrate preparation prior to pouring of the concrete. As a means of preventing buckling or angular displacement of such cold joints, it is common practice to insert smooth steel dowel rods, generally known as slip tubes or slip dowels, within the edge portions of adjoining concrete slabs in such a manner that the concrete slabs may slide freely along one or more of the slip dowels, thereby permitting linear expansion and contraction of the slabs while at the same time maintaining the slabs in a common plane and thus preventing undesirable buckling or unevenness of the cold joint and in adjacent slabs.
In order to function effectively, slip dowels must be accurately positioned parallel within the adjoining concrete slabs. The non-parallel positioning of the dowels will prevent the desired slippage of the dowels and will defeat the purpose of the “slip dowel” application. Additionally, the individual dowels must be placed within one or both of the slabs in such a manner as permit continual slippage or movement of the dowels within the cured concrete slab(s).
In commonplace to form large concrete slabs using monolithic or continuous concrete pour methods. Such slabs are formed by continuously pouring large quantities of concrete without the use of forms or cold joints in order to reduce costs. Therefore, fracturing of the slab is prevented by including tooled joints or sawcuts in the slab where cold joints would otherwise be needed. Additionally, concrete reinforcement material such as wire mesh or segments of rebar are initially placed into the area in which the continuous pour is to be made, and in particular those areas where it is contemplated that sawcuts will be included in the resultant slab for purposes of preventing fracturing thereof. The wire mesh or other reinforcement material is preferably elevated above ground level by the placement thereof upon a support foot or seat.
In addition to having concrete reinforcement material disposed within those portions of the slab in which a sawcut is to be made, it is also desirable to incorporate slip dowels into such portions to allow the separate sections of the slab which are defined by the sawcuts to move relative to each other while preventing any buckling or angular displacement thereof. One prior art method of incorporating slip dowels into those areas of a continuous pour where sawcuts are contemplated involves manually “stabbing” the slip dowels into predetermined locations of the uncured concrete pour. This method, however, is deficient in that there is no way to insure that the slip dowels will be manually positioned within the uncured concrete in parallel relation to each other, or will be maintained in parallel alignment to the top surface of the concrete pour during curing. As previously explained, if the dowel rods are not in parallel alignment, the separate sections of slab as defined by the sawcuts will be prevented from moving relative to each other.
Another prior art method of incorporating slip tubes into a monolithic pour involves manually tieing the slip dowels, or slip tubes to the reinforcement material in parallel relation to each other prior to the concrete pour being made. Manual tieing, however, is extremely time consuming and presents significant difficulties in securing the slip tubes to the reinforcement material in true parallel relation to each other. Additionally, the tied slip tubes are susceptible to displacement or shifting when impacted by the concrete during the pour thus moving the same out of parallel alignment with each other.
In another prior art configuration of the support structure may be fabricated from concrete reinforcing wire. Each top segment, side segment, and bottom portion may be formed from a single section of concrete reinforcing wire by bending such material into the desired generally U-shaped configuration. Then the top, side and base stringers may be welded at their respective locations in order to from the support structure slip tubes are then attached to the top side stringer.
The present invention addresses and overcomes the above-described deficiencies associated with the labor intensive formation of the support structure and slip tube placement in continuous concrete pours by providing prefabricated support structure that readily receives and inherently aligns the slip tubes accurately during the pouring of such concrete slabs. In this respect, the present invention provides an accurate and easy to use assembly for slip tube and dowel placement in a monolithic pour.
A concrete dowel slip tube assembly is provided for use in maintaining a planner consistency of a cured concrete slab formed on a support surface. The assembly comprises a plurality of elongate slip tubes, each having a length dimension and a tubular hollow interior compartment. Dowels are slidingly engageable to the hollow interior compartment to allow for translation along the interior compartment. A support frame defines a plurality of integral slip tube retaining members, disposed at preferably evenly spaced locations along the support frame, the retaining members being configured to receive and engage associated slip tubes to the support frame in a common defined orientation. The support frame and the retaining members are preferably formed as a unitary construction.
The slip tube retaining members are preferably configured to receive and orient the slip tubes along the frame length, substantially perpendicular to the support frame length.
The slip tube retaining members may comprise first and second opposing prongs, which collectively define arcuately contoured recess therebetween for receiving and retaining the slip tubes.
Alternately, the slip tube retaining members may comprise arcuately contoured straps, which define and arcuate recess for receiving and engaging the slip tubes. In one embodiment, the slip tubes are engaged to, or otherwise form a portion of the support frame, to define the unitary structure including the support frame (with the slip to retaining members) and the slip tubes.
A plurality of support seats, which are disposable about the support surface, and configured to receive and support the slip tubes, e.g., when the slip tubes are engaged to the support frame. The support seats may alternatively/additionally be configured to support the support frame (e.g., along the side supports or cross members) and dowels.
The support seats may include a height adjustable and screw and engager, for maintaining planner orientation of the support frame and the dowels over in a regular surface.
The engager may define a plurality of arcuate recesses for engaging the slip tubes, the dowels, the frame support side members and/or the frame support cross members.
Alternatively, the support frame may be formed to include downwardly extending support legs, which form a unitary construction with the support frame. The support legs may be provided with height adjustable feet, to maintain planner orientation of the support frame and the dowels, over in a regular surface.
In one embodiment, the support frame (including the slip tube engaging members), the slip tubes and the support seat, or the support legs, may be formed as a unitary structure.
These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which:
The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including various ways of engaging the slip tube to the support structure. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.
Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the present invention only, and not for purposes of limiting the same,
Referring now to
The slip tube 14 constructed in accordance with the present invention is used for supporting the concrete dowel 16 slidably insertable therein. As seen in
Referring to
Alternatively, the retaining member 35 may be implemented as straps or other retainers, such as arcuate straps 44, 45. Referring to
As will be apparent to those of ordinary skill in the art, the construction of a prefabricated support frame, having integral support tube retainer members, provide significant advantages in the construction of a concrete dowel slip tube assembly. By having the slip to slip tube retaining members integrated into the support frame, the orientation of the slip tubes, relative to the support frame, is fixed and does not require manual adjustment of the support frame, or manual alignment of the slip tubes relative to the support frame. This provides consistency of orientation of the slip tubes along the support frame and mitigates labor and skill requirements to properly array with the concrete reinforcing structure in a manner that permits linear expansion and contraction of the concrete slabs, while at the same time maintaining the slabs in a common plane, to prevent undesirable buckling and unevenness between adjacent slabs. Once the support frame is arrayed above the surface, e.g., upon the support seat or integral support legs, dowels can be extended into the slip tubes at one or both ends by simply translating the support structure to match up the support tubes with the other end of the dowels.
As further described below, the unitary construction may further include integral support legs, extending downwardly from the support frame, to avoid the need for arranging the support seats below the sport frame. The support tubes may also be formed integral with the support frame. These and other advantages of the present invention are described further below.
Referring again to
Clips 32, 33 and straps 44, 45 are configured on the surface of support structure 12, or formed within the support structure 12, to maintain a plurality of concrete dowel slip tubes 14 in a substantially parallel relationship to one another and parallel to a top surface 58 of concrete slab 42. Additionally, the clips 32, 33 and/or straps 44, 45, connected to the side segments 52, 54 of support structure 12. Each side segment 52, 54 of support structure 12 is attached to cross member 36 such that the side members 52, 54 are in parallel alignment with each other to maintain the slip tubes in substantially coplanar relationship. Additionally, each support seat 18 is sized such that each clip 32 and retainer 44 is elevated above the ground 50 in substantially the same vertical plane. In one embodiment, each support seat 18 has a height of between about 2.5 inches to about 24.0 inches. The clip 32 and/or retainer 44 are spaced to receive and engage the slip tube 14. As such, in one embodiment the length of cross member 36 is between about 6.0 inches to about 30.0 inches, and the cross member 26 may be spaced along the support structure between about 6.0 to about 30.0 inches.
The concrete dowel slip tube assembly 10 additionally comprises the support seat 18. As shown in
As seen in
In one embodiment, as shown at
In another embodiment, shown at
Now having described the components of the concrete dowel slip tube assembly 10, the function and method of using each component will be explained. Reference to the first embodiment of the support structure 12 will be made herein, yet it will be recognized that other embodiments support structure 12 can be interchanged with the described embodiment in the following description of use. First, slip tubes 14 are attached to the support structure 12 via clips 32, 33 or straps 44, 45. The slip tubes 14 are typically spaced about 6.0 to 30.0 inches between adjacent slip tubes. As seen in
Next, the support structure 12 is positioned in the location where a sawcut 70 will be made in the monolithic concrete slab 42 after pouring and curing thereof. As seen in
Before the concrete slab 42 is poured, the concrete support dowels 16 are inserted within a respective slip tube 14. As previously described above, the support structure 12 is configured to support the slip tubes 14 and support dowels 16 inserted therein in a substantially parallel and co-planar relationship to one another, and parallel to the top surface 58 of concrete slab 42. The support dowels 16 are slidable within a respective slip tube 14 in order to provide lateral displacement of the concrete slab 42 as will be further explained below. The extended end 40 of dowel 16 projects outwardly from the slip tube 14 such that the support structure 12 may become imbalanced and tend to tip toward surface 50. If this happens, then support seat 18 is attached to the extended end 40 of dowel 16 to provide additional support thereto. The support seat 18 has a height, or is adjustable to have a height which coaxially aligns the support dowel 16 with the central axis “A” of slip tube 14 when support dowel 16 is attached to a respective dowel engager 68 of support seat 18. The dowel 16 must be easily slidable within the slip tube 14 for proper operation. Therefore, the central axis “A” of slip tube 14 must be coaxially aligned with support dowel 16 in order to prevent binding of the dowel 16 within slip tube 14, as the slip tube 14 is slightly larger than the diameter of the support dowel 16. Additionally, support seat 18 aligns the support dowel 16 to axis “A” of slip tube 14 during pouring of the concrete because the weight of the concrete can cause the support dowel to bend and therefor bind on slip tube. As such, the support seat 18 provides support to extended end 40 of dowel 16 to maintain slip tube 14 substantially perpendicular alignment with support structure 12.
After having placed the dowels 16 into respective slip tubes 14, the concrete slab 42 is formed by pouring concrete around the support structure 12. The concrete encapsulates the support structure 12, the exposed portion of the support dowel 16 and the support seat 18. Since the support seat 18 is provided with openings 66 formed therein, the concrete is able to fully surround and encapsulate support seat 18. Therefore, support seat 18 can remain in place after the concrete has cured. Typically, the height of the support structure 12 is chosen to position the support dowels 16 midway between the top surface 58 of concrete slab 42 and the supporting ground surface 50.
After the concrete slab 42 has cured, the sawcut 70 is formed on the top surface 58 of concrete slab 42 by sawing the slab 42 with standard concrete construction techniques. The sawcut 70 is located perpendicular to the central axis “A” of the slip tubes 14. Additionally, the sawcut 70 must be located at the junction where the support dowel 16 enters the slip tube 14 (i.e., near the open end 22 of slip tube 14). Since the dowel 16 is longitudinally slidable within the slip tube 14, the concrete slab 42 may be laterally displaced about sawcut 70. The portion of the support dowel 16 extending within the slip tube 14 is allowed to move freely in a longitudinal direction, whereas the portion of the dowel 16 extending into the concrete slab 42 is frictionally retained therein. The closed end 24 of slip tube 14 prevents the seepage of concrete thereinto such that the portion of dowel 16 within the slip tube 14 is freely slidable in a generally horizontal direction. Therefore, the sawcut 70 is placed at the junction between the dowel 16 and slip tube 14 since this is the location whereby the dowel 16 is freely slidable horizontally. However, the dowel 16 is not movable in a vertical direction within slab 42 because it is encapsulated by concrete or retained within slip tube 14. Therefore, the dowel 16 can prevent buckling or angular displacement of concrete slab 34 in the area whereby dowel 16 is positioned.
The present invention accurately positions concrete support dowels 16 during the pouring of the monolithic concrete slab 42. As such, the positioning and configuration of the slip tubes 14 can be easily and quickly changed by varying the size of slip tube 14 and corresponding concrete support dowel 16, as well as the size of the slip tube support structure.
Additional modifications and improvements of the present invention may also be apparent to those of ordinary skill in the art such as varying the configuration of the slip tube support structure as well as other configurations for the slip tube retaining members. Thus, the particular combination of parts described and illustrated herein is intended to represent only certain embodiments of the present invention, and is not intended to serve as limitations of alternative devices within the spirit and scope of the invention.
