Static structures (e.g. – buildings) – Relatively yieldable preformed separator – Exposed separator between prefabricated components
Reexamination Certificate
2001-04-12
2002-06-11
Stephan, Beth A. (Department: 3635)
Static structures (e.g., buildings)
Relatively yieldable preformed separator
Exposed separator between prefabricated components
C052S396020, C052S573100, C052S742100
Reexamination Certificate
active
06401416
ABSTRACT:
BACKGROUND OF THE INVENTION
Concrete floors are typically composed of a plurality of rectangular slab panels placed on separate days and joined together by slip dowels (for load transfer) or tie rods (reinforcing bar—usually for resistance to earthquakes—or to increase the moment capacity of walls and foundations) or merely abutted to one another as the daily progression of slab panel placements ensures. The joints resultant from adjacent placements of smaller concrete slab panels are known as “bulkhead construction joints” (or “bulkhead joints”, or simply as “construction joints”), and should not be confused with sawn or tooled joints within each individual concrete floor slab placement that are used primarily for the organization and control of concrete cracking—such joints are commonly known as “control joints” or “contraction joints”. (Nor should they be confused with isolation joints which occur between slab panels and other building elements.) In essence, construction joints occur at the perimeter of every concrete slab panel (4 sides) that abuts another concrete slab panel.
Subsequently to slab placement, long after the concrete has hardened, the construction joints are filled with commonly known semi-rigid joint filler materials intended to close the gap between the slabs for the purposes of housekeeping and to provide a means of load transfer from the top edge of one concrete panel to another, thereby minimizing the possibility of edge break down under repeated traffic, esp. heavily loaded, small wheeled traffic commonly found in forklift environments.
The major problem with joint filler at construction joints is that it is not economical to fill the joint from the ground, up to the top of the slab and to do so would adhere the separate slab panels together, increasing the likelihood of undesirable cracking. Thus, construction joints are typically filled first with some backer material like sand or foam “backer-rod”, so the residual depth to fill with semi-rigid joint filler material is a fraction of the depth of the concrete slab itself. The consequences of this industry-wide approach may be summarized as follows:
1. Sand-like fillers tend to subside beneath the semi-rigid joint filler because the adjacent slab panels shrink away from each other, and slab panel edges tend to curl upward, providing a void for the sandy material to subside into.
2. Foam “backer-rod” materials provide no support beneath a joint filler subject to concentrated wheel loads.
3. The semi-rigid joint fillers harden to the width of the construction joint at the time of filling and are too rigid to accommodate thermal and drying shrinkage movement of the adjacent slab panels, losing adhesion with one panel or the other, or splitting itself, so that load transfer from panel edge to panel edge is lost. Also, and especially for shrinkage compensating concrete (SCC) floor slabs, the construction joint movement is so large relative to the original joint width, repeated impact from concentrated loads forces the joint filler materials downward into the joint, or results in a rebound of the filler so that it emerges from the joint.
As mentioned, SCC floor slabs typically have much wider joints than their counterpart slabs composed of traditional portland cement/pozzolanic materials, because SCC slab panels are subject to thermal and drying shrinkage movement as are their counterparts, but SCC slabs have no interior contraction joints at which to relieve the drying shrinkage and thermal movement, hence all the movement occurs at the construction joints. For instance, a traditional portland cement/pozzolanic concrete slab panel about 100′ by 100′ would usually have a control joint every 15′—two ways, or roughly 5 interior joints in each direction where the drying shrinkage and thermal movement may be approximately 0.01″ per joint, for instance. In contrast, a shrinkage compensating slab panel of equal size has no interior joints. So, in this example, the added movement at a shrinkage compensating construction joint would approximate 5×0.01″=0.05″ divided by 2 (one construction joint at the two opposing edges of each panel) or 0.025″ more than the construction joint of a typical slab. Therefore, it is more common for the joint filler in construction joints of a shrinkage compensating slab to come loose and become ineffective, requiring repeated expensive and wasteful refilling of the joint.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an economical and easy to install support mechanism for the joint filler in concrete slabs, hereafter referenced as a vee joint. The objective of this invention is accomplished by a vee joint having a first flange connected to a hinge and a second flange connected to the same hinge at an angle A from the first flange. The hinge may be a separately constructed device, but it is intended to typically be that point where a material is folded over upon itself. A trough is formed between the first flange, the second flange, and the hinge which is used to retain joint filler within a shrinkage compensating concrete floor slab construction joint. The flanges can be adjusted so the angle therebetween is increased or decreased to fit within various sized construction joints and to accommodate the movement of the floor joints as they become wider and narrower. The flange width may be enlarged or decreased to fit various joint depths. Additionally, the support provided by the rigid nature of the hinge minimizes the process wherein joint filler is forced downward into a joint by concentrated loads traversing it. Adhesion of the joint filler when in contact with the flanges minimizes joint filler from emerging from the joint.
The Vee joint of the present invention is primarily a V-shaped set of flanges joined by a hinge. The Vee joint is configured to be narrower at its base than the distance between its upper flanges, hence creating a “V” or “U” shaped cross-section. The vee joint is adapted to fit various size joints and it is used to retain the joint filler within a joint and prevent it from being pushed further into the joint or from being forced out of the joint due to impact.
The vee joint herein described can be used in floor joints that either have or do not have edge armor (embedded steel at the slab panel edge). In fact, the vee joint could be used in most any type of floor slab joint. The vee joint can be installed above load transfer devices (dowels) and rest upon them, providing more substantial support of the joint filler above. Where no load transfer device exists, the vee joint can be forced into a joint, the friction between its flanges and the concrete slab panels providing support for the joint filler, or it may be simply forced down into the joint to the base below the slab, where it will minimize the escape of preliminary sand-like fillers, increasing the longevity of the semi-rigid joint filler above them.
Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 1891530 (1932-12-01), Galassi
patent: 2198084 (1940-04-01), Jacobson
patent: 3124047 (1964-03-01), Graham
patent: 3593626 (1971-07-01), Crone
patent: 3604169 (1971-09-01), Smith
patent: D236715 (1975-09-01), Patterson
patent: D236716 (1975-09-01), Patterson
patent: 4128358 (1978-12-01), Compton
patent: 4423979 (1984-01-01), Brown
patent: 5282693 (1994-02-01), Daily, Jr.
Dykema Gossett PLLC
Glessner Brian E.
Kalman Floor Company
Stephan Beth A.
LandOfFree
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