Road structure – process – or apparatus – Pavement – Reinforced structure
Reexamination Certificate
1999-04-14
2001-04-03
Lillis, Eileen D. (Department: 3673)
Road structure, process, or apparatus
Pavement
Reinforced structure
C404S065000, C404S062000
Reexamination Certificate
active
06210070
ABSTRACT:
BACKGROUND OF THE INVENTION
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 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 to permit continual slippage or movement of the dowels within the cured concrete slab(s).
It is 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 support blocks or “chairs”.
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 dowels into a monolithic pour involves manually tieing the slip dowels 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 dowels to the reinforcement material in true parallel relation to each other. Additionally, the tied slip dowels 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.
The present invention addresses and overcomes the above-described deficiencies of prior art slip dowel placement in continuous concrete pours by providing a device that places slip dowels accurately during the pouring of such concrete slabs. In this respect, the present invention places slip dowels into a concrete slab through the use of slip tubes that are easily attached to a prefabricated support structure. Therefore, the present invention provides an accurate and easy system for slip dowel placement in a monolithic pour.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a concrete dowel slip tube for attachment to a wire mesh support structure. The slip tube comprises an elongate, tubular dowel receiving sheath having a proximal end, a distal end, an exterior surface and a hollow interior compartment extending longitudinally therein. The hollow interior compartment that is sized and configured to receive a concrete support dowel. The interior compartment has a generally circular cross-sectional configuration with a diameter between about 0.5 inches and about 1.0 inches. The longitudinal length of the sheath is between about 6.0 inches and about 30.0 inches.
Attached longitudinally to the exterior surface of the sheath is a clip sized and configured to frictionally retain the wire mesh support structure. The clip has a first prong portion and a second prong portion that define an arcuately contoured recess that is engagable to the support structure. The clip extends longitudinally along at least one-half the length of the sheath or from about the distal end to about the proximal end.
There is additionally provided a concrete dowel placement apparatus comprising a wire mesh support structure placeable upon a support surface and the concrete dowel slip tube previously described. The support structure comprises a base portion and an elevated portion having a plurality of top segments which extend in spaced, generally parallel relation to each other for attachment of the clip of a respective slip tube. Each of the top segments is configured to be in generally co-planar relationship to each other. Typically each top segment is elevated to a height of between about 2.5 inches and about 24 inches and spaced between about 6.0 inches and 30.0 inches between one another.
In a first embodiment of the support structure the elevated portion comprises a plurality of side segments which extend generally perpendicularly relative to respective ones of the top segments. Additionally, the base portion includes a plurality of base segments which extend generally perpendicularly to respective ones of the side segments. In a second embodiment of the placement apparatus the elevated portion of the support structure comprises a plurality of V-shaped members attached to the base portion and arranged to define multiple opposed pairs. Each of the V-shaped members define an apex such that each of the top segments are attached to and extend between the apices of a respective pair of V-shaped members.
The placement apparatus may be in further combination with an elongate concrete support dowel. The concrete support dowel is slidably insertable into the concrete dowel slip tube such that an end of the support dowel extends therefrom. A support foot may be further included in the placement apparatus of the present invention. The support foot is sized and configured to receive and support the end of the dowel extending from the slip tube and coaxially maintain the dowel in such position. As such, the interior compartment of the sheath defines a first axis and the dowel defines a second axis that is coaxially alignable with the first axis when the dowel is inserted into the interior compartment. The support foot is formed to be of a height which maintains the coaxial alignment of the first and second axes when the dowel support foot is placed upon the support surface and interfaced to the end of the dowel protruding from the sheath.
The present invention further comp
Shaw Lee A.
Shaw Ron D.
Addie Raymond W
Lillis Eileen D.
Stetina Kit M.
Stetina Brunda Garred & Brucker
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