Static structures (e.g. – buildings) – Relatively yieldable preformed separator – Separator inserted prior to or during pouring of two...
Reexamination Certificate
1999-05-05
2001-02-20
Stephan, Beth A. (Department: 3635)
Static structures (e.g., buildings)
Relatively yieldable preformed separator
Separator inserted prior to or during pouring of two...
C249S009000, C249S188000, C264S031000, C052S742140
Reexamination Certificate
active
06189278
ABSTRACT:
FIELD OF THE INVENTION
The field of art to which the invention relates comprises forming of a contraction joint in concrete poured facings such as the cantilevered nose cap of a swimming pool.
BACKGROUND OF THE INVENTION
Concrete decking placed around swimming pools is generally on the order of about four inch thickness divided into six foot by six foot bays to prevent adverse, unsightly cracking. This is effected by introducing a wecond plain system comprising placement of a contraction joint which penetrates the concrete when wet through one-third of its thickness. The resulting benefit is that the concrete tends to be weaker in and about the straight lines representing the contraction joint.
It is recognized that concrete when poured begins to hydrate and become chemically hot, so that during the first few hours of setting, the decking is at its most expanded state. As cooling begins, the concrete begins to contract and the wecond plain lines allow for contraction. The shrinkage cracks remain invisible beneath the contraction joint. By also extending the joint around the cantilevered face of the decking, the contraction crack thereat occurs unnoticed behind the nose cap.
Prior to about 1958 when plastic contraction joints were first introduced to the trade, concrete workers utilized a deep jointer displaced across the top of the freshly poured concrete to form the contraction joint. This jointer was attached to a long handle and produced a joint
1
to 1½ inches deep in straight lines across the concrete surface causing a wecond plain that allowed for concrete shrinkage. This method is still widely used throughout the concrete industry on, for example, sidewalks, wall caps, steps and anywhere controlled cracking of concrete is required.
DESCRIPTION OF THE PRIOR ART
Contraction joints for concrete and particularly in vertically oriented facings such as the curved cantilevered nose of a poured concrete pool decking has long been effected by use of either precast nose sections or by the use of a cutting tool after the concrete has set. While functioning well and affording a pleasing appearance, the cost of grooving by hand typically has run about $8.60 per linear foot while utilizing pre-cast units has run about $21.00 per linear foot.
While the foregoing costs have been recognized as somewhat exorbitant, it has not been known heretofore how they can be significantly reduced.
OBJECTS OF THE INVENTION
An object of the invention is to provide novel product and method for effecting a contraction joint on the face of concrete structures.
It is a further object of the invention to effect the previous object with a product and method in which the contraction joint can be formed during the pouring and curing of the concrete.
It is a still further object of the invention to effect the previous objects at a substantially lower cost than has been possible by techniques utilized heretofore.
SUMMARY OF THE INVENTION
This invention relates to the formation of contraction joints in concrete structures. More specifically, the invention relates to forming contraction joints in the face of concrete structures such as in the nose cap of swimming pool decking and at a substantially lower cost compared to the current costs of pre-cast units or hand cutting thereof.
For achieving the foregoing, an available form of a configured form board is selected to shape the face of the concrete when poured and in accordance herewith, is provided with a plurality of longitudinally spaced blade-like inserts removably secured on the interior of the form board. With the form board in place to receive the poured aggregate, the inserts laterally extend forward of the form board into the face-path of the concrete. Being that the blades penetrate the concrete, subsequent removal of the insert along with removal of the form board after the concrete has cured, results in a cast formation of a contraction joint thereat. Yet, with the inserts still in place, a cement finishing person using a straight edge for alignment, can rectilinearly advance a deep joint tool successively from each bladed insert toward the opposite side in order to effect continuity of the contraction joint from on the vertical edge to the adjoining horizontal surface.
Each insert is constructed of a suitable plastic composition such as polyethylene, PVC, etc. and can conveniently be formed by injection molding. It can be formed in a variety of different configurations to fit each and every form board profile. As a result, the cost of forming the contraction joint is typically reduced to less than about ten cents per linear foot, that can be appreciated, is significantly less than the cost of either pre-cast units or hand cutting the concrete face as noted supra.
The end result is that the poured aggregate, such as the wall cap of swimming pool decking forms a pre-cast appearance at a significantly lower cost than the pre-cast units or a hand carving of the prior art and can be utilized on any concrete face with which a form board is utilized. The virtues thereof can be readily appreciated by those skilled in the art.
The above noted features and advantages of the invention as well as other superior aspects thereof will be further appreciated by those skilled in the art upon reading the detailed description which follows in conjunction with the drawings.
REFERENCES:
patent: 1141057 (1915-05-01), Heltzel
patent: 3166816 (1965-01-01), Berg
patent: 3567171 (1971-03-01), Slominski
patent: 3968191 (1976-07-01), Stegmeier
patent: 4048270 (1977-09-01), Stegmeier
patent: 4574017 (1986-03-01), Stegmeier
patent: 5156791 (1992-10-01), Sano et al.
Glessner Brian E.
Rubin Daniel
Stephan Beth A.
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